WO2025203348A1 - Optical connector and method for manufacturing optical connector plug - Google Patents

Abstract

To provide an optical connector capable of connecting an optical fiber with low loss, and a method for manufacturing the optical connector plug.　An optical connector (200) has a waveguide (20) formed using a photocurable resin (13). The waveguide (20) is connected to a core end surface of an optical fiber (10), one end of which is fixedly inserted in an optical connector plug (100), and can transmit an optical signal of a core of the optical fiber (10) to the other end. An end surface of the other end of the waveguide (20) is formed in accordance with a position and size of a core end surface of a reference optical fiber (70) on an attachment/detachment end surface side of a reference connector plug (300) for waveguide production.

Description

Optical connector and method of manufacturing optical connector plug

This disclosure relates to a method for manufacturing an optical connector and an optical connector plug.

With the spread of the Internet, the transmission capacity of information networks is expanding year by year. Methods for increasing transmission capacity in optical fiber include time division multiplexing, wavelength division multiplexing, and space division multiplexing. In particular, space division multiplexing is a technology that achieves high capacity by placing multiple cores or multiple modes in a single optical fiber. With single-mode uncoupled multicore fiber, by using an interface such as fine-in-fan-out, it is possible to increase transmission capacity without changing the configuration of conventional transceiver equipment.

Furthermore, one method of increasing transmission capacity is mode multiplexing transmission technology, which places multiple propagation modes in a single core and transmits different signals in each mode, thereby increasing capacity. With this technology, an interface such as fine-in-fan-out is used to use each mode in each core as a different signal transmission path, thereby increasing transmission capacity.

In order to use space division multiplexing transmission technology in data centers, access networks, etc., it is necessary to lay multicore fiber optical cables that serve as transmission paths for space division multiplexing transmission. To maintain the scalability of laying multicore fiber cables, optical connectors that can connect multicore fibers are required. With multicore fiber connector technology, the fiber cores are positioned off-center relative to the outer diameter of the fiber, so they must be mounted with rotational alignment to achieve low connection loss. Non-patent documents 1 and 2 have proposed technologies for achieving low connection loss.

Morishima, T., Saito, Y., Shimakawa, Osamu, Manabe, K., Nakanishi, T., Sano, T., Hayashi, T., "Multicore fiber connection technology," IEICE General University, BCI-1-5, 2021. Hidetaka Terazawa, Takeshi Yukikawa, Keisuke Kondo, and Okihiro Sugihara, "Fabrication of near-infrared self-written optical waveguides and their application to multi-channel optical waveguides," IEICE General University, C-13-2, 2013.

(1) Regarding single-mode connectors with one core propagation mode Non-Patent Document 1 describes a method for suppressing rotational misalignment when fabricating a single-core or multi-core connector plug for connecting multicore fibers. However, this technology requires precise alignment, including rotational alignment, and has the problem of requiring the use of parts and rotational alignment methods with higher precision than conventional connectors.

Non-Patent Document 2 describes a technique for connecting specific combinations of multi-core fibers using self-forming waveguides. However, because optical connectors are required to be able to connect any combination, cores must be positioned in standardized design target positions, but the document does not describe a method for positioning cores in the design target positions.

(2) Mode multiplexing transmission with multiple core propagation modes When connecting cores with multiple propagation modes, mode conversion may occur at the optical connection point even if no optical loss occurs. In mode multiplexing transmission, different signals are transmitted in each mode, so if mode conversion occurs, the signals will interfere with each other, leading to signal degradation.

The technology in Non-Patent Document 1 discloses an average connection performance of 0.07 dB when connecting single-mode cores. For example, if this is a two-mode core, and the connection loss between the fundamental modes is 0.07 dB, and this loss is due to mode conversion from the fundamental mode to a higher-order mode, then the extinction ratio, i.e., the ratio of the light propagating in the fundamental mode before the connection point to the light converted to the higher-order mode, is -18 dB. For example, in wavelength multiplexing transmission, an extinction ratio of -30 dB or less is required in wavelength multiplexing/demultiplexing devices, and an extinction ratio of -18 dB can be said to be high for multiplexed transmission. As described above, the technology in Non-Patent Document 1 has issues with mode conversion.

Furthermore, the technology in Non-Patent Document 2 requires that cores be placed at the design target positions of the optical connector, but does not describe how to place the cores at the design target positions.

This disclosure has been made in consideration of the above circumstances, and its purpose is to provide an optical connector that can connect optical fibers with low loss, and a method for manufacturing an optical connector plug.

One aspect of the present disclosure is an optical connector having a waveguide formed using a photocurable resin, one end of the waveguide being connected to the core end face of an optical fiber inserted and fixed into an optical connector plug, and capable of transmitting an optical signal from the core of the optical fiber to the other end, the end face of the other end being formed according to the position and size of the core end face of a reference optical fiber on the detachable end face side of a reference connector plug used to fabricate the waveguide.

One aspect of the present disclosure is an optical connector having a waveguide formed using a photocurable resin, one end of the waveguide being connected to the core end face of an optical fiber inserted and fixed in an optical connector plug, and capable of transmitting an optical signal from the optical fiber core to the other end, the end face of the other end of the waveguide being formed according to the position and size of a light-transmitting hole in a photomask used to fabricate the waveguide.

One aspect of the present disclosure is a method for manufacturing an optical connector plug for use in an optical connector, the optical connector plug comprising: a ferrule capable of holding a connection end of an optical fiber and photocurable resin; the connection end of the optical fiber inserted and fixed within the ferrule; photocurable resin filled within the ferrule so as to abut against the connection end of the optical fiber; and a sealant forming a detachable end face of the ferrule and preventing the photocurable resin from leaking out; an end face of a reference optical fiber inserted and fixed in a reference connector plug is positioned opposite the detachable end face of the ferrule; the core of the optical fiber is irradiated with light of a wavelength that increases the refractive index of the photocurable resin and hardens it, and light of the same wavelength is irradiated from the core of the reference optical fiber onto the photocurable resin, thereby increasing the refractive index and hardening the irradiated portion of the photocurable resin, thereby forming a waveguide; the end face of the waveguide on the detachable end face side is formed according to the position and size of the core end face of the reference optical fiber on the detachable end face side of the reference connector plug.

One aspect of the present disclosure is a method for manufacturing an optical connector plug for use in an optical connector, the optical connector plug comprising: a ferrule capable of holding a connection end of an optical fiber and photocurable resin; the connection end of the optical fiber inserted and fixed within the ferrule; photocurable resin filled within the ferrule so as to abut against the connection end of the optical fiber; and a sealant forming a detachable end face of the ferrule and preventing the photocurable resin from leaking out; the method irradiates the photocurable resin with light of a wavelength that increases the refractive index of the photocurable resin and hardens it from the core of the optical fiber, and irradiates the photocurable resin with light of the same wavelength from the detachable end face side through a photomask, thereby increasing the refractive index of the irradiated portion of the photocurable resin and hardening it, thereby forming a waveguide; and the end face of the waveguide on the detachable end face side is formed according to the position and size of the light-transmitting hole in the photomask.

This disclosure provides an optical connector capable of connecting optical fibers with low loss, and a method for manufacturing an optical connector plug.

FIG. 1 is a diagram showing the structure of an optical connector plug of an optical connector. FIG. 2 shows a modified example of the sealing material of the optical connector plug. FIG. 3 is a diagram showing an example of the arrangement of a plurality of optical fibers in an optical connector plug. FIG. 4 is a diagram showing a modified example of the optical connector plug arrangement member. FIG. 5 is a diagram showing an example of a connection configuration of an optical connector. FIG. 6 is a diagram showing another example of the connection configuration of the optical connector. 7A to 7C are diagrams illustrating a first method for producing an optical connector plug. FIG. 8 is a diagram showing a waveguide of the optical connector plug shown in FIG. FIG. 9 is a diagram showing a modification of the first method for producing an optical connector plug. FIG. 10 is a diagram illustrating a second method for producing an optical connector plug. FIG. 11 is a diagram illustrating a method for producing an optical connector plug for connecting a multi-core fiber. FIG. 12 is a diagram showing a waveguide of the optical connector plug shown in FIG. FIG. 13 is a diagram showing an example of an optical connector plug structure of a single-fiber optical connector. FIG. 14 is a diagram showing a modified example of the sealing material of the optical connector plug of the single-fiber optical connector. FIG. 15 is a diagram showing an example of a connection configuration of a single-fiber optical connector. FIG. 16 is a diagram illustrating a first method for producing an optical connector plug for a single-fiber optical connector. FIG. 17 is a diagram showing a waveguide of the optical connector plug shown in FIG. FIG. 18 is a diagram illustrating a second method for producing an optical connector plug for a single-fiber optical connector. FIG. 19 is a diagram illustrating a method for producing an optical connector plug of a single-core optical connector for connecting a multi-core fiber. FIG. 20 is an enlarged view of a portion of the optical connector plug shown in FIG.

Next, several embodiments will be described in detail with reference to the drawings. In the description, identical components will be assigned the same reference numerals and duplicate explanations will be omitted.

The first and second embodiments describe single-mode embodiments, and the third and fourth embodiments describe multi-mode embodiments.

[First embodiment]
Fig. 1 is a diagram showing an example of the structure of a connector plug of an optical connector according to a first embodiment. Fig. 1 is a cross-sectional view (side cross-sectional view) of an optical connector plug 100 taken along a plane parallel to the longitudinal direction of an optical fiber 10.

The optical connector of this embodiment includes optical connector plugs 100, each of which has a waveguide formed using photocurable resin 13. One end of the waveguide is connected to the core end face of an optical fiber 10 inserted and fixed in the optical connector plug 100, and the optical signal from the core of the optical fiber 10 can be transmitted to the other end. The end face at the other end of the waveguide may be formed according to the position and size of the core end face of a reference optical fiber on the detachable end face side of a reference connector plug used for waveguide fabrication. The end face at the other end of the waveguide may also be formed according to the position and size of a light-transmitting hole in a photomask used for waveguide fabrication. The optical connector plug 100 may include a ferrule 11 capable of holding the connecting end of the optical fiber 10 and the photocurable resin 13, and a sealant 14 that forms the detachable end face of the ferrule 11 and prevents the photocurable resin from leaking out. The photocurable resin 13 is filled into the ferrule 11 so as to abut against the connecting end of the optical fiber 10.

The optical connector plug 100 shown in the figure comprises the connection ends of multiple optical fibers 10 inserted and fixed into the ferrule 11, the ferrule 11, adhesive 12, a photocurable resin 13 that forms a self-forming optical waveguide (hereinafter referred to as "waveguide"), a sealing material 14, and an alignment member 16. The end face 15 of the ferrule 11 may be formed at an angle.

The optical connector plug 100 is a multi-core optical connector plug, and may be, for example, an F12-type multi-core optical fiber connector (MT connector). The optical connector plug 100 may also be an F13-type multi-core optical fiber connector (MPO connector). In this case, the end face of the MT ferrule may be formed at an angle. The MT ferrule is housed in an MPO plug housing, and the MPO plug is connected within an MPO adapter. The multi-core optical connector is not limited to MT connectors or MPO connectors, as long as it can connect multiple optical fibers in a detachable manner.

The photocurable resin 13 is connected to the optical fiber 10 inside the ferrule 11. A waveguide capable of transmitting optical signals is formed in the photocurable resin 13. The ferrule 11 is filled with the photocurable resin 13.

The sealing material 14 is provided on the ferrule end surface 15 and prevents the photocurable resin 13 from leaking out of the ferrule 11. The sealing material 14 holds the photocurable resin 13 inside the ferrule 11. The sealing material 14 forms the detachable end surface of the ferrule 11. The sealing material 14 is also referred to as the detachable end surface.

As shown in Figure 1, the sealing material 14 may be arranged so that it protrudes from the ferrule end face 15. Alternatively, as shown in Figure 2, a portion of the ferrule end face 15 may be recessed, and the sealing material 14 may be embedded in the ferrule end face 15. The sealing material 14 may be arranged in any shape and in any manner, as long as it is possible to prevent the photocurable resin 13 from leaking out from the ferrule end face 15.

For example, glass or resin can be used for the sealing material 14. The sealing material 14 may have any shape that allows it to emit light propagating through the waveguide formed in the photocurable resin 13, or to propagate incident light through the waveguide. When using glass for the sealing material 14, the waveguide formed in the photocurable resin 53 and the waveguide capable of transmitting optical signals may be formed in the sealing material 14 by laser drawing.

Figure 3 is a diagram illustrating multiple optical fibers 10 arranged in an optical connector plug 100. Figure 3 is a cross-sectional view of the optical connector plug 100 cut along a plane perpendicular to the longitudinal direction of the optical fibers 10. The cross-sectional view shown is a cross-sectional view of the area where the adhesive 12 and the alignment member 16 are present.

Multiple optical fibers 10 are arranged at equal intervals by an alignment member 16 toward the ferrule end face 15, and are fixed to the ferrule 11 with adhesive 12. The adhesive 12 is injected through a hole (not shown) provided in the top of the ferrule 11.

In order to arrange the optical fibers 10 at equal intervals, the arrangement member 16 is formed with, for example, V-grooves, semicircular grooves, circular holes, etc. The shape of the arrangement member 16 may be any shape that allows the optical fibers 10 to be arranged at equal intervals. In the example shown in Figure 3, eight optical fibers 10 are arranged, but the number of optical fibers 10 is not limited to eight, as long as it is two or more.

As shown in Figure 4, the alignment member 16 may have a tapered shape to make it easier to insert the optical fiber 10. The optical fiber 10 may be, for example, a single-core fiber, a multi-core fiber, or a polarization-maintaining fiber, as long as it is an optical fiber that transmits light of any wavelength.

Figure 5 shows an example of the connection configuration of the optical connector 200 of this embodiment. Here, axial alignment is achieved by inserting a guide pin (not shown) into a guide hole (not shown) located on the ferrule end face 15, and a spring (not shown) applies pressure to the opposing optical connector plugs 100, causing the sealing materials 14 (detachable end faces) to tightly adhere to each other, thereby forming the optical connector 200. This allows the optical fiber 10 inserted and fixed in the opposing optical connector plugs 100 to be connected with low loss.

To reduce return loss, as shown in Figure 6, a refractive index matching material 18 may be applied between the opposing sealing materials 14. The refractive index matching material 18 may be in a gel or solid state. If a solid refractive index matching material 18 is used, there is no need to remove and reapply the refractive index matching material 18 when connecting or disconnecting the optical connector, which reduces the amount of work required to connect or disconnect the optical connector.

Figure 7 is a diagram illustrating a first manufacturing method for the optical connector plug 100 used in the optical connector 200 of this embodiment. In the first manufacturing method, the end face of the reference optical fiber 30 inserted and fixed in the reference connector plug 300 is positioned opposite the detachable end face 14 of the ferrule 11, and light of a wavelength that increases the refractive index of the photocurable resin 13 and hardens it is irradiated from the core of the optical fiber 10 onto the photocurable resin 13, while light of the same wavelength is irradiated from the core of the reference optical fiber 30 onto the photocurable resin 13, thereby increasing the refractive index and hardening the irradiated portion of the photocurable resin 13, thereby forming the waveguide 20. The end face of the waveguide 20 on the detachable end face side is formed according to the position and size of the core end face of the reference optical fiber 30 on the detachable end face side of the reference connector plug 300.

Specifically, a photocurable resin 13 is filled into the hollow space connecting the end face of the optical fiber placed in the ferrule 11 and the ferrule end face 15 (detachable end face 14). Then, a reference connector plug 300 for fabricating a waveguide is connected to the optical connector plug 100 of the optical connector 200. The reference connector plug 300 includes multiple optical fibers 30 (reference optical fibers), a ferrule 31, an adhesive 32, and an alignment member 36. The optical fiber 30 has a core 30a and a cladding 30b.

Then, light sources 19 and 39 with wavelengths that increase the refractive index and harden the photocurable resin 13 are connected to the optical fiber 10 of the optical connector plug 100 and the optical fiber 30 of the reference connector plug 300, respectively. Light of this wavelength is then irradiated from the cores 10a and 30a of each optical fiber 10 and 30. This increases the refractive index and hardens the irradiated portion of the photocurable resin 13, resulting in the creation of a waveguide 20 as shown in Figure 8. Figure 8 is an enlarged view of a portion of the cross-sectional view of the optical connector plug 100 shown in Figure 1. That is, the end face of the waveguide 20 on the detachable end face side is formed according to the position and size of the core end face of the optical fiber 30 on the detachable end face side of the reference connector plug 300. After the waveguide 20 is created, the reference connector plug 300 and the light source 19 are removed, and the optical connector plug 100 is completed.

In this way, the end face on the detachable end face side of the waveguide 20 produced by the first production method is formed according to the core end face of the reference connector plug 300, so the end face on the detachable end face side of the waveguide 20 of an optical connector plug 100 produced using the same reference connector plug 300 has the same shape and size and is formed in the same position on the ferrule end face 15. Therefore, by connecting two optical connector plugs 100 produced by the first production method, it is possible to produce an optical connector that can connect optical fibers with low loss.

As shown in Figure 9, a cladding 21 may be formed around the waveguide 20. After forming the waveguide 20, the photocurable resin 13 may be removed from the portion where the waveguide 20 is not formed, and the ferrule 11 may be filled with another photocurable resin 13b capable of forming a cladding with a lower refractive index than the waveguide 20. Light of a wavelength that hardens the other photocurable resin 13b may then be irradiated from the ferrule end face 15 side to harden the other photocurable resin 13b, thereby forming a cladding 21 around the waveguide 20.

Specifically, the photocurable resin 13 is removed from the injection port 22 provided in the ferrule 11, and instead photocurable resin 13b is injected, which can form a cladding 21 with a lower refractive index than the waveguide 20 when irradiated with light. Then, a light source 37 with a wavelength that causes the photocurable resin 13b to harden can be positioned near the ferrule end face 15, and the cladding 21 can be formed by irradiating the photocurable resin 13b with light 37a of that wavelength from the light source 37. An injection port 22 can be provided in advance in the ferrule 11 for removing the photocurable resin 13 and injecting the photocurable resin 13b.

The reference connector plug 300 may be an optical connector plug used in high-precision optical connectors manufactured with minimal deviation from the optical connector's design target. In the case of single-core fiber connectors, a reference connector specified by the IEC (International Electrotechnical Commission) may be used.

In the case of a multicore fiber connector without a reference connector, an optical connector with low connection loss may be selected, for example, using the following procedure. A plurality of optical connectors are fabricated in which the core positions are aligned using image alignment or other methods to minimize error from the design target, and those with the smallest error are selected from these to extract sample group A. Another plurality of optical connectors are fabricated in which the core positions are aligned, and those with the smallest error are selected from these to extract sample group B, which is different from sample group A. A plurality of optical connectors are fabricated in which the core positions are aligned, and those with the smallest error are selected from these to extract sample group C, which is different from sample groups A and B. The optical connectors of sample groups A, B, and C are then connected together to select an optical connector that achieves even lower connection loss. The optical connector plug of the optical connector selected in this manner may be used as the reference connector plug 300.

Figure 10 is a diagram illustrating a second manufacturing method for the optical connector plug 100 of the first embodiment. In the second manufacturing method, light of a wavelength that increases the refractive index of the photocurable resin 13 and hardens it is irradiated onto the photocurable resin 13 from the core of the optical fiber 10, and light of the same wavelength is irradiated onto the photocurable resin 13 from the detachable end face side through a photomask 42, thereby increasing the refractive index and hardening the irradiated portion of the photocurable resin 13, thereby forming the waveguide 20. The end face of the waveguide 20 on the detachable end face side is formed according to the position and size of the light-transmitting hole in the photomask 42.

Specifically, in the second manufacturing method, instead of using the reference connector plug 300, photolithography technology using a photomask 42 and light source 38 is used. Photocurable resin 13 is filled into the hollow space connecting the end face of the optical fiber placed in the ferrule 11 and the ferrule end face 15 (detachable end face 14). Then, a photomask 42 and a light source 38 with a wavelength that increases the refractive index of the photocurable resin 13 and hardens it are placed near the ferrule end face 15 of the optical connector plug 100. In addition, a light source 19 with a wavelength that increases the refractive index of the photocurable resin 13 and hardens it is connected to the optical fiber 10 of the optical connector plug 100.

By irradiating the photocurable resin 13 with light of a wavelength that increases the refractive index and hardens it from the core 10a of the optical fiber 10 and the photomask 42, the refractive index of the irradiated portion of the photocurable resin 13 increases and hardens, creating the waveguide 20.

The photomask 42 has light-transmitting holes corresponding to the core size at locations corresponding to the core design positions of the optical connector. The photomask 42 has a structure in which the light-transmitting holes allow light to pass through, while the remaining areas block light. The photomask 42 can be made, for example, of a metal plate with holes drilled, or of a glass plate with metal vapor-deposited on its surface. The end face of the waveguide 20 on the detachable end face 14 side is formed according to the position and size of the light-transmitting holes in the photomask 42. After the waveguide 20 is created, the photomask 42 and light sources 19 and 38 are removed to produce the optical connector plug 100.

In this way, the end face on the detachable end face of the waveguide 20 produced by the second production method is formed according to the light-transmitting holes of the photomask 42, so the end face on the detachable end face of the waveguide 20 of an optical connector plug 100 produced using the same photomask 42 will have the same shape and size and be formed in the same position on the ferrule end face 15. Therefore, by connecting two optical connector plugs 100 produced by the second production method, an optical connector capable of connecting optical fibers with low loss can be produced. Note that the cladding 21 may also be formed in the second production method in the same way as in the first production method.

In this embodiment, the waveguide 20 was formed using the reference connector plug 300 or photolithography technology, but these methods are not limiting as long as the waveguide 20 can be fabricated in such a way that the core position of the optical connector plug 100 has minimal error from the design target.

Figure 11 is a diagram illustrating a method for fabricating an optical connector plug 100 for connecting a multicore fiber. Here, a method for fabricating the optical connector plug 100 using the first fabrication method described above will be described as an example. A reference connector plug 300 is connected to the optical connector plug 100. The optical fiber 10 of the optical connector plug 100 and the optical fiber 30 of the reference connector plug 300 are each connected to a single-core fiber 40 via a fan-out 41. Light sources 19, 39 with a wavelength that increases the refractive index and hardens the photo-curable resin 13 are connected to each single-core fiber 40, and light of that wavelength is irradiated from the cores 10a, 30a of the optical fibers 10, 30.

This causes the refractive index of the photocurable resin 13 to increase and harden in the irradiated areas, forming multiple waveguides 20 as shown in Figure 12. After the waveguides 20 are created, the optical connector plug 100 is produced by removing the reference connector plug 300 and the fan-out 41. By connecting two optical connector plugs 100 made using the same reference connector plug 300, an optical connector capable of connecting optical fibers with low loss can be produced. Figures 11 and 12 show an example of a multicore fiber with four cores, but the multicore fiber may have two or more cores, and the core arrangement may be any desired arrangement.

Second Embodiment
Fig. 13 is a diagram showing an example of a connector plug structure of an optical connector according to the second embodiment. Fig. 13 is a cross-sectional view (side cross-sectional view) of an optical connector plug 500 taken along a plane parallel to the longitudinal direction of the optical fiber 50.

The optical connector of this embodiment includes optical connector plugs 500, each of which has a waveguide formed using photocurable resin 53. One end of the waveguide is connected to the core end face of an optical fiber 50 inserted and fixed in the optical connector plug 500, and the optical signal from the core of the optical fiber 50 can be transmitted to the other end. The end face at the other end of the waveguide may be formed according to the position and size of the core end face of a reference optical fiber on the detachable end face side of a reference connector plug used for waveguide fabrication. The end face at the other end of the waveguide may also be formed according to the position and size of a light-transmitting hole in a photomask used for waveguide fabrication. The optical connector plug 500 may include a ferrule 51 capable of holding the connecting end of the optical fiber 50 and the photocurable resin 53, and a sealant 54 that forms the detachable end face of the ferrule 51 and prevents the photocurable resin from leaking out. The photocurable resin 53 is filled into the ferrule 51 so as to abut against the connecting end of the optical fiber 50.

The optical connector plug 500 shown is a single-core optical connector plug, and includes the connection end of a single optical fiber 50 inserted and fixed into the ferrule 51, the ferrule 51, a plug frame 52, a photocurable resin 53 that forms a self-forming optical waveguide (waveguide), a sealant 54, a tab 56, a flange 57, a spring 58, and a stop ring 59. The sealant 54 is placed on the ferrule end face 55 to prevent the photocurable resin 53 filled in the ferrule 51 from leaking out.

The single-core optical connector plug 500 may be an F04 type optical fiber connector (SC connector). Also, instead of an SC connector, the optical connector plug 500 may be an F14 type optical fiber connector (MU connector).

The optical connector plug 500 may have any shape that allows the single-core optical fiber 50 adhesively fixed to the ferrule 51 to be connected to an opposing optical fiber via an adapter (not shown). In other words, the presence or absence of the flange 57, spring 58, stop ring 59, plug frame 52, and knob 56, as well as their shapes, are not limited to those shown in Figure 13. The single-core optical connector of this embodiment is not limited to an SC connector or an MU connector, as long as it can connect a single-core optical fiber in a detachable manner.

The photocurable resin 53 is connected to the optical fiber 50 inside the ferrule 51, and is used to form a self-forming optical waveguide capable of transmitting optical signals. The photocurable resin 53 is prevented from flowing out of the ferrule end face 55 by the sealing material 54, and is held inside the ferrule 51.

The sealing material 54 may be arranged so as to protrude from the ferrule end face 55 as shown in FIG. 13, or may be arranged so as to be embedded in the ferrule end face 55 by making the ferrule end face 55 concave as shown in FIG. 14. The sealing material 54 may be of any shape and arrangement as long as it can prevent the photocurable resin 53 from leaking out from the ferrule end face 55. For example, glass or resin may be used for the sealing material 54. The sealing material 54 may have any shape as long as it can emit light propagating through the waveguide formed in the photocurable resin 53 or propagate incident light into the waveguide. When glass is used for the sealing material 54, the waveguide formed in the photocurable resin 53 and the waveguide capable of transmitting optical signals may be formed in the sealing material 54 by laser drawing.

The single-core optical fiber 50 may be, for example, a single-core fiber, a multi-core fiber, or a polarization-maintaining fiber, as long as it is an optical fiber capable of transmitting light of any wavelength.

Figure 15 shows an example of a connection configuration for an optical connector according to the second embodiment. Axial alignment is achieved by inserting two opposing ferrules 51 into a sleeve 63 attached to an adapter (not shown). Then, a pressing force is applied to the optical fiber 50 and the ferrule end face 55 by a spring 58, forming an optical connector 600 in a configuration in which the sealing materials 54 are in close contact with each other, and connecting the optical fiber 50.

To reduce return loss, a refractive index matching material (not shown) may be applied between the sealing materials 54. The refractive index matching material may be in gel or solid form. If a solid refractive index matching material is used, there is no need to remove and reapply the matching material when connecting or disconnecting the optical connector, which reduces the amount of work required to connect or disconnect the optical connector.

16 is a diagram illustrating a first method for manufacturing the optical connector plug 500 of the second embodiment. In the first manufacturing method, the end face of the reference optical fiber 70 inserted and fixed in the reference connector plug 700 is positioned opposite the detachable end face 54 of the ferrule 51, and light of a wavelength that increases the refractive index of the photocurable resin 53 and hardens it is irradiated from the core of the optical fiber 50 onto the photocurable resin 53. At the same time, light of the same wavelength is irradiated from the core of the reference optical fiber 70 onto the photocurable resin 53, thereby increasing the refractive index and hardening the irradiated portion of the photocurable resin 53, thereby forming a waveguide 60. The end face of the waveguide 60 on the detachable end face side is formed according to the position and size of the core end face of the reference optical fiber 70 on the detachable end face side of the reference connector plug 700.

Specifically, photocurable resin 53 is filled into the hollow space connecting the end face of the optical fiber placed in the ferrule 51 and the ferrule end face 55 (detachable end face 54). Then, a reference connector plug 700 is connected to the optical connector plug 500. Light sources 69 and 89 with a wavelength that increases the refractive index of the photocurable resin 53 and hardens it are connected to the optical fiber 50 of the optical connector plug 500 and the optical fiber 70 of the reference connector plug 700, respectively. Light of this wavelength is irradiated onto the photocurable resin 53 from the cores 50a and 70a of the optical fibers 50 and 70. This increases the refractive index of the irradiated portion of the photocurable resin 53 and hardens it, forming a waveguide 60 as shown in FIG. 17. That is, the end face of the waveguide 60 on the detachable end face side is formed according to the position and size of the core end face of the optical fiber 70 on the detachable end face side of the reference connector plug 700. After creating the waveguide 60, the reference connector plug 700 and the light source 69 are removed to create the optical connector plug 500.

In this way, the end face on the detachable end face of the waveguide 60 produced by the first production method is formed according to the core end face of the reference connector plug 700, and therefore the end face on the detachable end face of the waveguide 60 of an optical connector plug 500 produced using the same reference connector plug 700 has the same shape and size and is formed in the same position on the ferrule end face 55. Therefore, by connecting two optical connector plugs 500 produced by the first production method, it is possible to produce an optical connector that can connect optical fibers with low loss.

After the waveguide 60 is created, a cladding may be formed in the same manner as in the first manufacturing method of the first embodiment. Specifically, after the waveguide is created, the photocurable resin 53 is removed from an injection port (not shown) formed in the ferrule 51, and instead a photocurable resin capable of forming a cladding with a lower refractive index than the waveguide by light irradiation is injected. A light source with a wavelength that causes the photocurable resin for the cladding to harden may be prepared, and the cladding may be formed by irradiating light from the light source.

The reference connector plug 700 may be an optical connector plug used in high-precision optical connectors manufactured with minimal deviation from the optical connector's design target. In the case of single-core fiber connectors, a reference connector specified by the IEC (International Electrotechnical Commission) may be used.

In the case of a multi-core fiber connector without a reference connector, an optical connector with low connection loss may be selected, for example, using the following procedure. A plurality of optical connectors are fabricated in which the core positions are aligned using image alignment or other methods to minimize error from the design target, and those with the smallest error are selected from these to extract sample group A. A further plurality of optical connectors are fabricated in which the core positions are aligned, and those with the smallest error are selected from these to extract sample group B, which is different from sample group A. A further plurality of optical connectors are fabricated in which the core positions are aligned, and those with the smallest error are selected from these to extract sample group C, which is different from sample groups A and B. The optical connectors of sample groups A, B, and C are then connected together to select an optical connector that achieves even lower connection loss. The optical connector plug of the optical connector selected in this manner may be used as the reference connector plug 700.

Figure 18 is a diagram illustrating a second manufacturing method for the optical connector plug 500 of the second embodiment. In the second manufacturing method, light of a wavelength that increases the refractive index of the photocurable resin 53 and hardens it is irradiated onto the photocurable resin 53 from the core of the optical fiber 50, and light of the same wavelength is irradiated onto the photocurable resin 53 from the detachable end face side through a photomask 62, thereby increasing the refractive index and hardening the irradiated portion of the photocurable resin 53, thereby forming the waveguide 60. The end face of the waveguide 60 on the detachable end face side is formed according to the position and size of the light-transmitting hole in the photomask 62.

Specifically, the second manufacturing method uses photolithography with a photomask 62 and light source 88 instead of using a reference connector plug 700. Photocurable resin 53 is filled into the hollow space connecting the end face of the optical fiber placed in the ferrule 51 and the ferrule end face 55 (detachable end face 54). Then, a photomask 62 and a light source 88 with a wavelength that increases the refractive index of the photocurable resin 53 and hardens it are placed near the ferrule end face 55 of the optical connector plug 500. In addition, a light source 69 with a wavelength that increases the refractive index of the photocurable resin 53 and hardens it is connected to the optical fiber 50 of the optical connector plug 500.

By irradiating light of a wavelength that increases the refractive index of the photocurable resin 53 and hardens it from the core 50a of the optical fiber 50 and the photomask 62, respectively, the refractive index of the irradiated portion of the photocurable resin 53 increases and hardens, creating a waveguide 60.

The photomask 62 has light-transmitting holes corresponding to the core size at locations corresponding to the core design positions of the optical connector. The photomask 62 has a structure in which the light-transmitting holes allow light to pass through, while the remaining areas block light. The photomask 62 can be made, for example, of a metal plate with holes drilled, or of a glass plate with metal vapor-deposited on its surface. The end face of the waveguide 60 on the detachable end face 54 side is formed according to the position and size of the light-transmitting holes in the photomask 62. After the waveguide 60 is created, the photomask 62 and light sources 69 and 88 are removed to produce the optical connector plug 500.

In this way, the end face on the detachable end face of the waveguide 60 produced by the second production method is formed according to the light-transmitting holes of the photomask 62, and therefore the end face on the detachable end face of the waveguide 60 of an optical connector plug 500 produced using the same photomask 62 has the same shape and size and is formed in the same position on the ferrule end face 55. Therefore, by connecting two optical connector plugs 500 produced by the second production method, an optical connector capable of connecting optical fibers with low loss can be produced. Note that the cladding may also be formed in the second production method, as in the first production method.

In this embodiment, the waveguide 20 was formed using the reference connector plug 700 or photolithography technology, but the method is not limited to these, as long as it is possible to fabricate the waveguide 20 so that the core position of the optical connector plug 100 has minimal error from the design target.

Figure 19 is a diagram illustrating a method for fabricating an optical connector plug 500 for connecting a multicore fiber. Here, as an example, a method for fabricating the optical connector plug 500 using the first fabrication method described above is described. A reference connector plug 700 is connected to the optical connector plug 500.

The optical fiber 50 of the optical connector plug 500 and the optical fiber 70 of the reference connector plug 700 are each connected to a single-core fiber 80 via a fan-out 61. Light sources 69, 89 with a wavelength that increases the refractive index and hardens the photocurable resin 53 are connected to each single-core fiber 80, and light of that wavelength is irradiated onto the photocurable resin 53 from the cores 50a, 70a of the optical fibers 50, 70.

This causes the refractive index of the photocurable resin 13 in the irradiated area to increase and harden, creating multiple waveguides 60 as shown in Figure 20. After the waveguides 60 are created, the reference connector plug 700 and fan-out 61 are removed to create the optical connector plug 500. By connecting two optical connector plugs 500 created using the same reference connector plug 700, an optical connector that can connect optical fibers with low loss can be created. Figures 19 and 20 show an example of a multicore fiber with four cores, but the multicore fiber may have two or more cores, and the core arrangement may be any desired arrangement.

[Third embodiment]
FIG. 13 is a diagram showing an example of a connector plug structure of an optical connector according to a third embodiment. The connector plug structure of this embodiment is similar to the connector plug structure of the second embodiment described above. That is, the optical connector plug 500 of this embodiment has a waveguide formed using a photocurable resin 53, one end of which is connected to the core end face of an optical fiber 50 inserted and fixed in the optical connector plug 500, and which is capable of transmitting an optical signal from the core of the optical fiber 50 to the other end. The end face of the other end of the waveguide may be formed according to the position and size of the core end face of a reference optical fiber on the detachable end face side of a reference connector plug used for waveguide fabrication. Furthermore, the end face of the other end of the waveguide may be formed according to the position and size of a light-transmitting hole in a photomask used for waveguide fabrication. The optical connector plug 500 may also have a ferrule 51 capable of holding the connection end of the optical fiber 50 and the photocurable resin 53, and a sealant 54 that forms the detachable end face of the ferrule 51 and prevents the photocurable resin from leaking. The photocurable resin 53 is filled into the ferrule 51 so as to abut against the connection end of the optical fiber 50 .

The optical connector plug 500 of the illustrated embodiment is a single-core optical connector plug, and includes a single optical fiber 50, a ferrule 51, a plug frame 52, a photocurable resin 53 that forms a self-forming optical waveguide (waveguide), a sealant 54 (detachable end face), a knob 56 (housing), a flange 57, a spring 58, and a stop ring 59. The sealant 54 is placed on the ferrule end face 55 to prevent the photocurable resin 53 filled in the ferrule 51 from leaking out. The single-core optical connector plug 500 can be, for example, an SC connector, an MU connector, or other optical connector plug, but is not limited to these.

The optical connector plug 500 may have any shape that allows the single-core optical fiber 50 adhesively fixed to the ferrule 51 to be connected to an opposing optical fiber via an adapter (not shown). In other words, the presence or absence of the flange 57, spring 58, stop ring 59, plug frame 52, and knob 56, as well as their shapes, are not limited to those shown in Figure 16. The single-core optical connector of this embodiment is not limited to an SC connector or an MU connector, as long as it can connect a single-core optical fiber in a detachable manner.

The photocurable resin 53 is connected to the optical fiber 50 inside the ferrule 51, and is used to form a self-forming optical waveguide capable of transmitting optical signals. The photocurable resin 53 is prevented from leaking out of the ferrule end face 55 by the sealing material 54, and is held inside the ferrule 51.

One end of the waveguide is connected to the core end face of the optical fiber 50, and the other end is connected to the sealing material 54, which is the detachable end face. In other words, the optical waveguide in the photocurable resin 53 is formed so as to connect the end face of the optical fiber 50 to the design target position of the optical connector core on the detachable end face 54.

The sealing material 54 may be arranged so as to protrude from the ferrule end face 55 as shown in FIG. 16, or may be arranged so as to be embedded in the ferrule end face 55 by making the ferrule end face 55 concave as shown in FIG. 17. The sealing material 54 may be of any shape and arrangement as long as it can prevent the photocurable resin 53 from leaking out from the ferrule end face 55. For example, glass or resin may be used for the sealing material 54. The sealing material 54 may have any shape as long as it can emit light propagating through the waveguide formed in the photocurable resin 53 or propagate incident light into the waveguide. The waveguide formed in the photocurable resin 53 and a waveguide capable of transmitting optical signals may be formed in the sealing material 54 by laser drawing.

The single-core optical fiber 50 of this embodiment may be, for example, a single-core multimode fiber or a multi-core multimode fiber, as long as it is an optical fiber that transmits light of any wavelength in multiple propagation modes. In this embodiment, we will explain the case where a multi-core multimode fiber is used.

A first manufacturing method for the optical connector plug of this embodiment will be described using Figure 16. In the first manufacturing method, the end face of the reference optical fiber 70 inserted and fixed in the reference connector plug 700 is positioned opposite the detachable end face 54 of the ferrule 51, and light of a wavelength that increases the refractive index of the photocurable resin 53 and hardens it is irradiated from the core of the optical fiber 50 onto the photocurable resin 53. Light of the same wavelength is also irradiated from the core of the reference optical fiber 70 onto the photocurable resin 53, thereby increasing the refractive index and hardening the irradiated portion of the photocurable resin 53, thereby forming a waveguide 60. The end face of the waveguide 60 on the detachable end face side is formed according to the position and size of the core end face of the reference optical fiber 70 on the detachable end face side of the reference connector plug 700.

Specifically, photocurable resin 53 is filled into the hollow space connecting the end face of the optical fiber placed in the ferrule 51 and the ferrule end face 55 (detachable end face 54). Then, a reference connector plug 700 is connected to the optical connector plug 500. Light sources 69 and 89 with a wavelength that increases the refractive index of the photocurable resin 53 and hardens it are connected to the optical fiber 50 of the optical connector plug 500 and the optical fiber 70 of the reference connector plug 700, respectively, and light of that wavelength is irradiated onto the photocurable resin 53 from the cores 50a and 70a of the optical fibers 50 and 70. This increases the refractive index and hardens the irradiated portion of the photocurable resin 53, forming a waveguide 60 as shown in FIG. 17. That is, the end face of the waveguide 60 on the detachable end face side is formed according to the position and size of the core end face of the optical fiber 70 on the detachable end face side of the reference connector plug 700. After creating the waveguide 60, the reference connector plug 700 and the light source 69 are removed to create the optical connector plug 500.

In this way, the end face on the detachable end face of the waveguide 60 produced by the first production method is formed according to the core end face of the reference connector plug 700, and therefore the end face on the detachable end face of the waveguide 60 of an optical connector plug 500 produced using the same reference connector plug 700 has the same shape and size and is formed in the same position on the ferrule end face 55. Therefore, by connecting two optical connector plugs 500 produced by the first production method, it is possible to produce an optical connector that can connect optical fibers with low loss.

A high-precision connector manufactured with minimal error from the design target core position may be used as the reference connector plug 700. If a suitable high-precision connector is not available, for example, as described in the second embodiment, multiple optical connectors may be manufactured with the core position aligned by image alignment or the like so that there is minimal error from the design target, and from these, those with minimal error may be selected using end face image inspection or the like to extract three sample groups A, B, and C. The optical connectors in each sample group may be connected to select connector combinations that achieve the lowest connection loss, and the optical connector plugs of the selected optical connectors may be used as the reference connector plug 700.

The light sources 69, 89 may have the same wavelength as the communication light to be transmitted through the optical connector, and may be propagated in the same propagation mode as the propagation mode used for communication to generate the waveguide 60. For example, when connecting a multimode fiber that uses the three propagation modes of LP01, LP11, and LP02, one method is to first propagate the light output from the light sources 69, 89 in the optical fiber 50 in the LP01 mode to harden the photocurable resin 53, then propagate it in the LP11 mode to harden the photocurable resin 53, and then propagate it in the LP02 mode to harden the photocurable resin 53.

After creating the waveguide, it is also possible to remove the photocurable resin 53, inject a photocurable resin that can be irradiated with light to form a cladding with a lower refractive index than the waveguide, prepare a light source with a wavelength that will harden the injected photocurable resin, and irradiate the injected photocurable resin with light of a wavelength that will harden the injected photocurable resin to form the cladding.

Alternatively, a photocurable resin 53 that is cured at two or more different wavelengths may be used, and after forming the waveguide, a cladding with a low refractive index may be formed by curing the remaining uncured photocurable resin 53 using a light source with a wavelength different from that used when forming the waveguide.

The refractive index of the cladding changes depending on whether or not the cladding is cured, and if it is cured, the physical properties of the photocurable resin injected and the wavelength used for curing. If the refractive index of the cladding changes, the mode field diameter of the light propagating through the formed waveguide changes. This can be used to measure the loss and mode conversion state after forming the waveguide, and by changing the refractive index of the cladding as necessary, the mode field diameter of the waveguide can be changed and the loss and mode conversion state can be improved.

The formed waveguide has an extremely fine structure and is at risk of being destroyed when external forces are applied. However, in this embodiment, the waveguide is formed within the ferrule 51 and sealing material 54, and is therefore protected from external forces by the ferrule 51. The ferrule 51 is protected from external forces by the plug frame 52. The plug frame 52 is protected from external forces by the knob 56. In this way, this embodiment can provide an optical connector in which the waveguide is less likely to be damaged.

An example of the connection configuration of the optical connector according to the third embodiment will be described using Figure 15. Axial alignment is achieved by inserting two opposing ferrules 51 into a sleeve 63 attached to an adapter (not shown). Then, a pressing force is applied to the optical fiber 50 and ferrule end face 55 by a spring 58, forming an optical connector 600 in such a way that the detachable end faces 54 are in close contact with each other, and connecting the optical fiber 50. A refractive index matching material may be applied between the detachable end faces 54 to reduce return loss.

When using the sleeve 63 and ferrule 51, if components complying with the international standard IEC 61755-3-1 are used, the maximum optical fiber core misalignment will be 2.0 μm.

For example, to shift the core by 2.0 μm in a self-written optical waveguide, a waveguide with a short distance of about 20 μm is sufficient. Because the waveguide is short, there is almost no optical loss due to propagation through the waveguide.

As described above, by using the optical connector 600 of this embodiment, it is possible to reduce the amount of axial misalignment of the optical fiber 50. As a result, the length of the waveguide required in the optical connector plug 500 can be shortened, and optical loss in the waveguide can be suppressed. Furthermore, in this embodiment, the waveguide is formed using light of the same wavelength and propagation mode as the communication light emitted from the core of the optical fiber 50. This allows the waveguide to be formed in a shape that follows the shape of the communication light, thereby suppressing propagation mode conversion within the waveguide.

A second manufacturing method for the optical connector plug of this embodiment will be described using Figure 15. In the second manufacturing method, light of a wavelength that increases the refractive index of the photocurable resin 53 and hardens it is irradiated onto the photocurable resin 53 from the core of the optical fiber 50, and light of the same wavelength is irradiated onto the photocurable resin 53 from the detachable end face side through a photomask 62, thereby increasing the refractive index and hardening the irradiated portion of the photocurable resin 53, thereby forming a waveguide 60. The end face of the waveguide 60 on the detachable end face side is formed according to the position and size of the light-transmitting hole in the photomask 62.

Specifically, the second manufacturing method uses photolithography with a photomask 62 and light source 88 instead of using a reference connector plug 700. Photocurable resin 53 is filled into the hollow space connecting the end face of the optical fiber placed in the ferrule 51 and the ferrule end face 55 (detachable end face 54). Then, a photomask 62 and a light source 88 with a wavelength that increases the refractive index of the photocurable resin 53 and hardens it are placed near the ferrule end face 55 of the optical connector plug 500. In addition, a light source 69 with a wavelength that increases the refractive index of the photocurable resin 53 and hardens it is connected to the optical fiber 50 of the optical connector plug 500.

By irradiating the core 50a of the optical fiber 50 and the photomask 62 with light of the above wavelength, the refractive index of the irradiated portion of the photocurable resin 53 increases and hardens, creating the waveguide 60. After the waveguide 60 is created, the photomask 62 and light sources 69 and 88 are removed, and the optical connector plug 500 is produced.

The photomask 62 has light-transmitting holes corresponding to the core size at locations corresponding to the core design positions of the optical connector. The photomask 62 is designed so that the light-transmitting holes allow light to pass through, while the remaining areas block light. The photomask 62 can be, for example, a metal plate with holes drilled, or a glass plate with metal vapor-deposited on its surface. The end face of the waveguide 60 on the detachable end face 54 side is formed according to the position and size of the light-transmitting holes in the photomask 62.

In this way, the end face on the detachable end face of the waveguide 60 produced by the second production method is formed according to the light-transmitting holes of the photomask 62, and therefore the end face on the detachable end face of the waveguide 60 of an optical connector plug 500 produced using the same photomask 62 has the same shape and size and is formed in the same position on the ferrule end face 55. Therefore, by connecting two optical connector plugs 500 produced by the second production method, an optical connector capable of connecting optical fibers with low loss can be produced. Note that the cladding may also be formed in the second production method, as in the first production method.

The light sources 69 and 88 may have the same wavelength as the communication light to be transmitted through the optical connector, and the light from the light sources 69 and 88 may be propagated in the same propagation mode as the propagation mode used for communication to generate the optical waveguide 60.

Figure 19 is a diagram illustrating a method for fabricating an optical connector plug 500 for connecting a multicore fiber. Here, as an example, a method for fabricating the optical connector plug 500 using the first fabrication method described above is described. A reference connector plug 700 is connected to the optical connector plug 500.

The optical fiber 50 of the optical connector plug 500 and the optical fiber 70 of the reference connector plug 700 are each connected to a single-core fiber 80 via a fan-out 61. Light sources 69, 89 with a wavelength that increases the refractive index and hardens the photocurable resin 53 are connected to each single-core fiber 80, and light of that wavelength is irradiated onto the photocurable resin 53 from the cores 50a, 70a of the optical fibers 50, 70.

This causes the refractive index of the photocurable resin 53 in the irradiated area to increase and harden, creating multiple waveguides 60 as shown in Figure 20. After the waveguides 60 are created, the reference connector plug 700 and fan-out 61 are removed to create the optical connector plug 500. By connecting two optical connector plugs 500 created using the same reference connector plug 700, an optical connector that can connect optical fibers with low loss can be created. Figures 19 and 20 show an example of a multicore fiber with four cores, but the number of cores in the multicore fiber may be two or more, and the core arrangement may be any desired arrangement.

[Fourth embodiment]
FIG. 1 is a diagram showing an example of a connector plug structure of an optical connector according to a fourth embodiment. The optical connector plug 100 of this embodiment is a multi-fiber optical connector plug similar to the optical connector plug 100 of the first embodiment. The optical connector plug 100 of this embodiment has a waveguide formed using a photocurable resin 13, one end of which is connected to a core end face of an optical fiber 10 inserted and fixed into the optical connector plug 100, and which is capable of transmitting an optical signal from the core of the optical fiber 10 to the other end. The end face at the other end of the waveguide may be formed according to the position and size of the core end face of a reference optical fiber on the detachable end face side of a reference connector plug for waveguide fabrication. Furthermore, the end face at the other end of the waveguide may be formed according to the position and size of a light-transmitting hole in a photomask for waveguide fabrication.

The optical connector plug 100 may have a ferrule 11 capable of holding the connection end of the optical fiber 10 and the photocurable resin 13, and a sealant 14 that forms the detachable end face of the ferrule 11 and prevents the photocurable resin from leaking out. The photocurable resin 13 is filled inside the ferrule 11 so that it abuts against the connection end of the optical fiber 10.

The optical connector plug 100 shown in the figure has connection ends of multiple optical fibers 10 inserted and fixed into a ferrule 11, the ferrule 11, adhesive 12, a photocurable resin 13 that forms a self-forming optical waveguide, a sealing material 14 (detachable end face), and an alignment member 16. A multi-fiber optical connector is sufficient if it can connect multiple optical fibers in a detachable manner all at once, and is not limited to multi-fiber optical connectors such as MT connectors and MPO connectors.

The photocurable resin 13 is connected to the optical fiber 10 inside the ferrule 11, and a waveguide 20 capable of transmitting optical signals is formed in the photocurable resin 13. One end of the waveguide 20 is connected to the end face of the core 10a of the optical fiber 10, and the other end is connected to the detachable end face 14. The waveguide 20 in the photocurable resin 13 is formed to connect the design target position of the optical connector core on the detachable end face 14 with the end face of the core 10a of the optical fiber 10.

The sealing material 14 may be arranged so as to protrude from the ferrule end face 15 as shown in FIG. 1, or may be arranged so as to be embedded in the ferrule end face 15 by making the ferrule end face 15 concave as shown in FIG. 2. The sealing material 14 may have any shape that prevents the photocurable resin 13 from leaking out from the ferrule end face 15. The sealing material 14 may be made of, for example, glass or resin, and may have any shape that allows light propagating through the waveguide 20 formed in the photocurable resin 13 to be emitted, or allows incident light to propagate to the waveguide 20 formed in the photocurable resin 13. When a glass material is used for the sealing material 14, the waveguide formed in the photocurable resin 53 and a waveguide capable of transmitting optical signals may be formed in the sealing material 14 by laser drawing.

As shown in Figure 3, multiple optical fibers 10 are arranged at equal intervals by an arranging member 16 toward the ferrule end face 15, and are adhered and fixed to the ferrule 11 by adhesive 12 injected through a hole (not shown) provided in the top of the ferrule 11. In order to arrange the optical fibers 10 at equal intervals, the arranging member 16 is provided with, for example, a V-groove, a semicircular groove, or a circular hole. However, the grooves and holes provided in the arranging member 16 may have any shape as long as they can arrange the optical fibers 10 at equal intervals. In Figure 4, eight optical fibers are arranged, but the number of optical fibers 10 is not limited to eight, as long as it is two or more.

The multiple optical fibers 10 may be, for example, single-core multimode fibers or multi-core multimode fibers, and may be optical fibers that transmit light of any wavelength in multiple propagation modes. In this embodiment, we will explain the case where a multi-core multimode fiber is used.

An example of the connection configuration of the optical connector 200 of this embodiment will be described using Figure 5. Here, axial alignment is performed by inserting a guide pin (not shown) into a guide hole (not shown) located on the ferrule end face 15, and a spring (not shown) applies pressure to the opposing optical connector plugs 100, causing the sealing materials 14 (detachable end faces) to tightly adhere to each other, thereby forming the optical connector 200. This allows the optical fibers 10 inserted and fixed in the opposing optical connector plugs 100 to be connected with low loss. A refractive index matching material may be applied between the sealing materials 14 to reduce return loss.

A first manufacturing method for the optical connector plug of the fourth embodiment will be described using Figure 7. In the first manufacturing method, the end face of the reference optical fiber 30 inserted and fixed in the reference connector plug 300 is positioned opposite the detachable end face 14 of the ferrule 11, and light of a wavelength that increases the refractive index of the photocurable resin 13 and hardens it is irradiated from the core of the optical fiber 10 onto the photocurable resin 13, while light of the same wavelength is irradiated from the core of the reference optical fiber 30 onto the photocurable resin 13, thereby increasing the refractive index and hardening the irradiated portion of the photocurable resin 13, thereby forming a waveguide 20. The end face of the waveguide 20 on the detachable end face side is formed according to the position and size of the core end face of the reference optical fiber 30 on the detachable end face side of the reference connector plug 300.

Specifically, photocurable resin 13 is filled into the hollow space connecting the end face of the optical fiber placed in the ferrule 11 and the ferrule end face 15 (detachable end face 14). Then, a reference connector plug 300 is connected to the optical connector plug 100. The reference connector plug 300 comprises multiple optical fibers 30, a ferrule 31, an adhesive 32, and an alignment member 36. Light sources 19, 39 with a wavelength that increases the refractive index of the photocurable resin 13 and hardens it are connected to the optical fibers 10 of the optical connector plug 100 and the optical fibers 30 of the reference connector plug 300, respectively, and light of that wavelength is irradiated onto the photocurable resin 13 from the cores 10a, 30a of the optical fibers 10, 30. This increases the refractive index and hardens the irradiated portion of the photocurable resin 13, forming a waveguide 20 as shown in FIG. 8. That is, the end face of the waveguide 20 on the detachable end face side is formed according to the position and size of the core end face of the optical fiber 30 on the detachable end face side of the reference connector plug 300. After creating the waveguide 20, the reference connector plug 300 and the light source 19 are removed to produce the optical connector plug 100.

In this way, the end face on the detachable end face side of the waveguide 20 produced by the first production method is formed according to the core end face of the reference connector plug 300, so the end face on the detachable end face side of the waveguide 20 of an optical connector plug 100 produced using the same reference connector plug 300 has the same shape and size and is formed in the same position on the ferrule end face 15. Therefore, by connecting two optical connector plugs 100 produced by the first production method, it is possible to produce an optical connector that can connect optical fibers with low loss.

The light from light sources 19 and 39 may have the same wavelength as the communication light to be transmitted through the optical connector, and the light may be propagated in the same propagation mode as that used for communication to generate waveguide 20.

Alternatively, as shown in FIG. 9, a cladding 21 may be formed around the waveguide 20. Specifically, after the waveguide 20 is created, the photocurable resin 13 is removed through an injection port 22 provided in the ferrule 11, and instead photocurable resin 13b is injected, which can form a cladding 21 with a lower refractive index than the waveguide 20 when irradiated with light. Then, a light source 37 with a wavelength that hardens the photocurable resin 13b is prepared, and the cladding 21 may be formed by irradiating light 37a of said wavelength from the light source 37. An injection port 22 may be provided in advance in the ferrule 11 for removing the photocurable resin 13 and injecting the photocurable resin 13b.

A high-precision connector manufactured with minimal error from the design target core position may be used as the reference connector plug 700. If a suitable high-precision connector is not available, for example, as described in the second embodiment, multiple optical connectors may be manufactured with the core position aligned by image alignment or the like so that there is minimal error from the design target, and from these, those with minimal error may be selected using end face image inspection or the like to extract three sample groups A, B, and C. The optical connectors in each sample group may be connected to select connector combinations that achieve the lowest connection loss, and the optical connector plugs of the selected optical connectors may be used as the reference connector plug 700.

A second manufacturing method for the optical connector plug 100 of the fourth embodiment will be described using Figure 10. In the second manufacturing method, the photocurable resin 13 is irradiated with light of a wavelength that increases the refractive index and hardens the photocurable resin 13 from the core of the optical fiber 10, and light of the same wavelength is also irradiated onto the photocurable resin 13 from the detachable end face side through a photomask 42, thereby increasing the refractive index and hardening the irradiated portion of the photocurable resin 13, thereby forming the waveguide 20. The end face of the waveguide 20 on the detachable end face side is formed according to the position and size of the light-transmitting hole in the photomask 42.

Specifically, the second fabrication method uses photolithography with a photomask 42 and light source 38 instead of using a reference connector plug 300. The hollow space connecting the end face of the optical fiber placed in the ferrule 11 and the ferrule end face 15 (detachable end face 14) is filled with photocurable resin 13. A photomask 42 and a light source 38 with a wavelength that increases the refractive index of the photocurable resin 53 and hardens it are then placed near the ferrule end face 15 of the optical connector plug 100. A light source 19 with a wavelength that increases the refractive index of the photocurable resin 13 and hardens it is connected to the optical fiber 10 of the optical connector plug 100. Light with the wavelength is then irradiated from the core 10a of the optical fiber and the photomask 42, respectively, causing an increase in the refractive index and hardening of the irradiated portion of the photocurable resin 13, thereby creating a waveguide 20.

The photomask 42 has light-transmitting holes corresponding to the core size at locations corresponding to the core design positions of the optical connector. The photomask 42 has a structure in which the light-transmitting holes allow light to pass through, while the remaining areas block light. The photomask 42 can be made, for example, of a metal plate with holes drilled, or of a glass plate with metal vapor-deposited on its surface. The end face of the waveguide 20 on the detachable end face 14 side is formed according to the position and size of the light-transmitting holes in the photomask 42. After the waveguide 20 is created, the photomask 42 and light sources 19 and 38 are removed to produce the optical connector plug 100.

In this way, the end face on the detachable end face of the waveguide 20 produced by the second production method is formed according to the light-transmitting holes of the photomask 42, so the end face on the detachable end face of the waveguide 20 of an optical connector plug 100 produced using the same photomask 42 will have the same shape and size and be formed in the same position on the ferrule end face 15. Therefore, by connecting two optical connector plugs 100 produced by the second production method, it is possible to produce an optical connector that can connect optical fibers with low loss. Note that the cladding 21 may also be formed in the second production method in the same way as in the first production method.

The light sources 19 and 38 may have the same wavelength as the communication light to be transmitted through the optical connector, and the light from the light sources 19 and 38 may be propagated in the same propagation mode as the propagation mode used for communication to generate the optical waveguide 20.

In this embodiment, the waveguide 20 was formed using the reference connector plug 300 or photolithography technology, but these methods are not limiting as long as the waveguide 20 can be fabricated in such a way that the core position of the optical connector plug 100 has minimal error from the design target.

Using Figure 11, we will explain a method for manufacturing an optical connector plug 100 for connecting a multicore fiber. Here, we will explain a method for creating the optical connector plug 100 using the first manufacturing method described above as an example. A reference connector plug 300 is connected to the optical connector plug 100.

The optical fiber 10 of the optical connector plug 100 and the optical fiber 30 of the reference connector plug 300 are each connected to a single-core fiber 40 via a fan-out 41. A light source 19, 39 with a wavelength that increases the refractive index of the photocurable resin 13 and hardens it is connected to each single-core fiber 40, and light of that wavelength is irradiated onto the photocurable resin 13 from the cores 10a, 30a of the optical fibers 10, 30.

This causes the refractive index of the photocurable resin 13 to increase and harden in the irradiated portion, forming a plurality of waveguides 20 as shown in Fig. 12. After the waveguides 20 are formed, the reference connector plug 300 and the fan-out 41 are removed, thereby producing the optical connector plug 100.
An optical connector capable of connecting optical fibers with low loss can be fabricated by connecting two optical connector plugs 100 fabricated using the same standard connector plug 300. Although an example of a multi-core fiber having four cores is shown in Figures 11 and 12, the number of cores in the multi-core fiber may be two or more, and the core arrangement may be any arrangement.

The optical connectors of the first to fourth embodiments described above have a waveguide formed using a photocurable resin, one end of which is connected to the core end face of an optical fiber inserted and fixed in an optical connector plug, and which is capable of transmitting an optical signal from the core of the optical fiber to the other end, with the end face of the other end being formed according to the position and size of the core end face of the reference optical fiber on the detachable end face side of the reference connector plug used to fabricate the waveguide.

The optical connectors of the first to fourth embodiments have a waveguide formed using a photocurable resin, one end of which is connected to the core end face of an optical fiber inserted and fixed in an optical connector plug, and which is capable of transmitting an optical signal from the optical fiber core to the other end, and the end face of the other end of the waveguide is formed according to the position and size of the light-transmitting hole in a photomask used to fabricate the waveguide.

In a first method for producing (manufacturing) an optical connector plug for use in the optical connectors of the first to fourth embodiments, the optical connector plug includes a ferrule capable of holding a connection end of an optical fiber and photocurable resin, the connection end of the optical fiber inserted and fixed within the ferrule, photocurable resin filled within the ferrule so as to abut against the connection end of the optical fiber, and a sealant that forms a detachable end face of the ferrule and prevents the photocurable resin from leaking out. The end face of a reference optical fiber inserted and fixed in a reference connector plug is positioned opposite the detachable end face of the ferrule, and light of a wavelength that increases the refractive index of the photocurable resin and hardens it is irradiated from the core of the optical fiber onto the photocurable resin, and light of the same wavelength is irradiated from the core of the reference optical fiber onto the photocurable resin, thereby increasing the refractive index and hardening the irradiated portion of the photocurable resin, thereby forming a waveguide. The end face of the waveguide on the detachable end face side is formed according to the position and size of the core end face of the reference optical fiber on the detachable end face side of the reference connector plug.

In a second method for producing (manufacturing) an optical connector plug for use in the optical connectors of the first to fourth embodiments, the optical connector plug includes a ferrule capable of holding a connection end of an optical fiber and photocurable resin, the connection end of the optical fiber inserted and fixed within the ferrule, photocurable resin filled within the ferrule so as to abut against the connection end of the optical fiber, and a sealant that forms the detachable end face of the ferrule and prevents the photocurable resin from leaking out. Light of a wavelength that increases the refractive index of the photocurable resin and hardens it is irradiated from the core of the optical fiber onto the photocurable resin, and light of the same wavelength is irradiated onto the photocurable resin from the detachable end face side through a photomask, thereby increasing the refractive index and hardening the irradiated portion of the photocurable resin, thereby forming a waveguide. The end face of the waveguide on the detachable end face side is formed according to the position and size of the light-transmitting hole in the photomask.

As a result, this embodiment provides an optical connector that can connect single-mode and multi-mode optical fibers with low loss, and also makes it possible to easily manufacture an optical connector plug for this optical connector.

Specifically, by combining optical connector plugs 100 in which waveguides are formed using the same reference connector or the same photomask, a low-loss optical connector can be provided. Furthermore, according to this embodiment, an optical connector plug for an optical connector that does not require precise core alignment can be easily manufactured.

Note that this disclosure is not limited to the above embodiments, and various modifications and combinations are possible.

10, 30, 50, 70 Optical fiber 10a, 30a, 50a, 70a Core 10b, 30b, 50b, 70b Cladding 100, 500 Optical connector plug 11, 31, 51, 71 Ferrule 12, 32 Adhesive 13, 13b, 53 Photocurable resin 14, 54 Sealant (detachable end face)
15, 55 Ferrule end face 16, 36 Arrangement member 18 Refractive index matching material 19, 37, 38, 39, 69, 88, 89 Light source 20, 60 Waveguide (self-written optical waveguide)
200, 600 Optical connector 21 Cladding 22 Inlet 300, 700 Reference connector plug 37a 38a, 88a Light 40, 80 Single-core fiber 41, 61 Fan-out 42, 62 Photomask 52, 72 Plug frame 56, 76 Knob 57, 77 Flange 58, 78 Spring 59, 79 Stop ring 63 Sleeve

Claims (8)

a waveguide formed using a photocurable resin;
The waveguide has one end connected to the core end face of an optical fiber inserted and fixed in an optical connector plug, and is capable of transmitting an optical signal from the core of the optical fiber to the other end, and the end face of the other end of the waveguide is formed in accordance with the position and size of the core end face of a reference optical fiber on the detachable end face side of a reference connector plug for waveguide fabrication. a waveguide formed using a photocurable resin;
The waveguide has one end connected to the core end face of an optical fiber inserted and fixed in an optical connector plug, and is capable of transmitting an optical signal from the optical fiber core to the other end, and the end face of the other end of the waveguide is formed according to the position and size of the light-transmitting hole in a photomask used to fabricate the waveguide. The optical connector plug comprises:
a ferrule capable of holding the connection end of the optical fiber and the photocurable resin;
3. The optical connector according to claim 1, further comprising: a sealant that forms a detachable end face of the ferrule and prevents the photocurable resin from leaking out. A method for manufacturing an optical connector plug for use in an optical connector, comprising:
The optical connector plug comprises:
a ferrule capable of holding a connection end of an optical fiber and a photocurable resin;
a connection end of the optical fiber inserted and fixed in the ferrule;
a photocurable resin filled in the ferrule so as to abut against the connection end of the optical fiber;
a sealing material that forms a detachable end surface of the ferrule and prevents the photocurable resin from leaking out,
an end face of a reference optical fiber inserted and fixed in a reference connector plug is arranged opposite the detachable end face of the ferrule;
a waveguide is formed by irradiating the photocurable resin with light of a wavelength that increases the refractive index of the photocurable resin and hardens the resin from the core of the optical fiber, and by irradiating the photocurable resin with light of the same wavelength from the core of the reference optical fiber, thereby increasing the refractive index of the light-irradiated portion of the photocurable resin and hardening the resin;
the end face of the waveguide on the detachable end face side is formed in accordance with the position and size of the core end face of the reference optical fiber on the detachable end face side of the reference connector plug. A method for manufacturing an optical connector plug for use in an optical connector, comprising:
The optical connector plug comprises:
a ferrule capable of holding a connection end of an optical fiber and a photocurable resin;
a connection end of the optical fiber inserted and fixed in the ferrule;
a photocurable resin filled in the ferrule so as to abut against the connection end of the optical fiber;
a sealing material that forms a detachable end surface of the ferrule and prevents the photocurable resin from leaking out,
light having a wavelength that increases the refractive index of the photocurable resin and hardens the resin is irradiated onto the photocurable resin from the core of the optical fiber, and light of the wavelength is irradiated onto the photocurable resin from the detachable end face side through a photomask, thereby increasing the refractive index of the light-irradiated portion of the photocurable resin and hardening the resin, thereby forming a waveguide;
the end face of the waveguide on the attachment/detachment end face side is formed in accordance with the position and size of the light transmitting hole of the photomask. After forming the waveguide, the photocurable resin is removed from a portion where the waveguide is not formed, and another photocurable resin capable of forming a clad having a refractive index lower than that of the waveguide is filled into the ferrule;
6. The method for manufacturing an optical connector plug according to claim 4, further comprising irradiating the other photocurable resin with light of a wavelength that causes the other photocurable resin to harden from the detachable end face side, thereby hardening the other photocurable resin and forming the cladding around the waveguide. 5. The method for manufacturing an optical connector plug according to claim 4, wherein the light irradiated from the core of the optical fiber and the light irradiated from the core of the reference optical fiber have the same wavelength and propagation mode as the communication light to be transmitted through the optical connector. 6. The method for manufacturing an optical connector plug according to claim 5, wherein the light irradiated from the core of the optical fiber and the light irradiated through the photomask have the same wavelength and propagation mode as the communication light to be transmitted through the optical connector.