CN102707451A - Polarization light splitting and merging device and method for producing same - Google Patents

Abstract

The invention provides a polarization light splitter and combiner and a manufacturing method thereof. The polarization light splitter and combiner has a first single-fiber collimator equipped with a first polarization-maintaining fiber, a second single-fiber collimator with a second polarization-maintaining fiber A collimator and a third single-fiber collimator installed with a single-mode optical fiber, and a light splitting and combining device, the third single fiber collimator is located outside the first light transmission surface of the splitting and combining device, wherein the first A light direction changing device is provided between the single fiber collimator and/or the second single fiber collimator and the second light transmission surface of the light splitting and combining device, and the light direction changing device is provided with at least one reflecting surface. The method includes installing a plurality of single-fiber collimators equipped with optical fibers on a substrate, arranging light splitting and combining devices on the substrate, rotating the plurality of single-fiber collimators around their own axes, and adjusting the polarized light splitting and combining devices. Extinction Ratio. The invention can reduce the volume of the polarization splitter and combiner, and the extinction ratio can be adjusted flexibly and conveniently, and the extinction ratio can also be made very high.

Description

Polarization beam splitter and combiner and its manufacturing method

technical field

The invention relates to an optical device, in particular to a polarization splitter and combiner for splitting or combining polarized light and a manufacturing method of the polarization splitter and combiner.

Background technique

With the development of network communication, the data transmission speed of the optical fiber network is getting faster and faster, and the requirement for the capacity of the optical fiber network is also getting higher and higher. Existing optical fiber network transmission systems use a large number of polarization-maintaining devices, such as polarized beam splitters and combiners (PMBCs) and polarization couplers (PMTCs), which are used to split, combine, and split polarized light. In the traditional erbium-doped fiber amplifier or Raman amplifier system, because the extinction ratio (ER) of the pump light source is not high, generally 18 decibels can meet the working requirements. However, with the development of 40GB or higher-capacity optical fiber transmission systems, there are higher requirements for the extinction ratio of polarization-maintaining devices.

Referring to Fig. 1, existing a kind of polarization light splitter light combiner has a birefringent crystal 10, and the incident surface 11 of birefringent crystal 10 is provided with two single-fiber collimators 13,15 outside, single-fiber collimator 13, Polarization maintaining optical fibers 14 and 16 are installed in 15 respectively. A single-fiber collimator 17 is provided outside the exit surface 12 of the birefringent crystal 10 , and a single-mode optical fiber 18 is installed in the single-fiber collimator 17 . The single-mode fiber referred to herein may be a polarization-maintaining single-mode fiber or a non-polarization-maintaining single-mode fiber. The single-mode fiber 18 in FIG. 1 is a polarization-maintaining fiber.

The polarization state of the light beam L11 emitted from the polarization-maintaining fiber 14 is fixed and perpendicular to the direction of the paper, and the polarization state of the light beam L12 emitted from the polarization-maintaining fiber 16 is also fixed and parallel to the direction of the paper. Therefore, the polarization states of the light beam L11 and the light beam L12 are Two beams of light perpendicular to each other. After the light beam L11 and the light beam L12 enter the birefringent crystal 10 from the incident surface 11 , they form light beams L13 and L14 respectively, and the polarization state does not change. Finally, the light beams L13 and L14 are emitted from the exit surface 12 and combined to form a light beam L15, which is incident on the polarization-maintaining fiber 18 in the single-fiber collimator 17, so as to realize the light combination of the light beams.

Of course, according to the reversible principle of light propagation, the polarization beam splitter and combiner shown in FIG. 1 can also be used as a polarization beam splitter. When used as a polarization splitting device, the light beam emerges from the polarization-maintaining fiber 18, and is split by the birefringent crystal 10, and the two beams after splitting parallelly emerge from the birefringent crystal 10, and finally enter the polarization-maintaining optical fiber 14, 16 respectively .

However, the distance between the two beams divided into two beams after the beam passes through the birefringent crystal 10 is proportional to the path of the beam in the birefringent crystal 10, and the single fiber collimators 13, 15 are cylindrical and have a large diameter , if in order to ensure that the beams emitted from the birefringent crystal 10 can be accurately and parallelly incident on the polarization-maintaining fibers 14, 16, the length of the birefringent crystal 10 needs to be set very long, which will cause the volume of the polarization splitter and combiner Large and expensive to produce.

Referring to Fig. 2, another existing polarization beam splitting light combiner is provided with a polarization beam splitting prism 20, is provided with a beam splitting film 21 inside the polarization beam splitting prism 20, is provided with a single fiber collimator 25 outside the incident surface 22, single fiber collimator A polarization maintaining optical fiber 26 is installed in the straightener 25 . A single-fiber collimator 27 is arranged outside an exit surface 23 of the polarization beam-splitter prism 20, and a polarization-maintaining optical fiber 28 is installed in the single-fiber collimator 27. A collimator 29, a polarization-maintaining fiber 30 is installed in the single-fiber collimator 29.

After the beam L21 emitted from the polarization-maintaining fiber 26 and the beam L22 emitted from the polarization-maintaining fiber 28 are incident on the dichroic film 21, they are combined to form a beam L23. Since the polarization states of the beam L21 and the beam L22 are perpendicular to each other, the combined light beams form The light beam L23 contains two mutually perpendicular polarization states, and the light beam L23 is incident into the polarization-maintaining fiber 30 .

Since the three single-fiber collimators 25, 27, and 29 of the polarization beam splitter and combiner are respectively located outside the three directions of the polarization beam splitter prism 20, the volume of the polarization beam splitter and combiner will also be relatively large.

Therefore, the Chinese utility model patent with the notification number CN2482108Y discloses an invention named "a new type of polarization beam combiner". The structure of the polarization beam combiner is shown in FIG. 3 . The polarization beam combiner has a Wollaston prism 31, a double-fiber collimator 33, and a single-fiber collimator 34. Two parallel polarization-maintaining fibers are installed in the double-fiber collimator 33, and the single-fiber collimator A single-mode optical fiber is installed in the 34, and the Wollaston prism is composed of two wedges made of crystals with mutual crystal axes, and is used for splitting or combining light beams.

The polarization states of the two light beams L31 and L32 transmitted in the double fiber collimator 33 are perpendicular to each other, and the two light beams L31 and L32 are combined on the bonding surface 32 of the two crystals of the Wollaston prism to form a light beam L33, and the light beam L33 passes through The single-mode fiber in the single-fiber collimator 34 exits.

Although the above-mentioned polarization combiner has a small volume, the adjustment of the extinction ratio of the double-fiber collimator is not ideal in practical applications. Referring to Fig. 4 and Fig. 5, the polarization-maintaining fiber 36 is a single-mode fiber with a circular cross section, the middle part of the polarization-maintaining fiber 36 is a core 37, and through-holes 38, 39 are respectively provided on both sides of the core 37. The through holes 38 and 39 are respectively filled with different light-transmitting materials. The connecting line between the centers of the two through holes 38 and 39 passes through the center of the cross section, and the connecting line is the fast axis of the polarization-maintaining fiber 36, that is, the Y axis, and the line perpendicular to the fast axis is the slow axis of the polarization-maintaining fiber 36, that is, the X axis. axis. When the polarization state of the light beam propagating in the polarization maintaining fiber 36 is parallel to the fast axis or the slow axis, the polarization state of the light beam will remain constant and will not change.

Moreover, when the polarization state of the linearly polarized beam incident on the polarization-maintaining fiber 36 is perpendicular or parallel to the fast axis, the extinction ratio of the beam is the highest, and as the angle formed between the polarization state of the beam and the fast axis increases, the extinction ratio gradually decreases, Therefore, the extinction ratio of the polarization splitter and combiner can be adjusted by rotating the single-fiber collimator installed with the polarization-maintaining fiber.

However, it is difficult for a dual-fiber collimator to adjust the extinction ratio as easily as a single-fiber collimator. Therefore, in the production process of the above-mentioned polarization beam combiner, it takes a lot of time to adjust the extinction ratio of the device, which greatly increases This not only increases the production difficulty of the polarization beam combiner, but also increases its production cost.

In addition, since the polarization-maintaining fiber 36 can maintain the performance of the polarization-maintaining fiber only when the fiber itself has stress, the glue in the dual-fiber collimator 33 has a different expansion coefficient from the polarization-maintaining fiber 36, and the glue will affect the polarization-maintaining fiber at high and low temperatures. 36 produces stress, and the distribution of glue in the dual-fiber capillary of the dual-fiber collimator 33 is not circularly symmetrical to the polarization-maintaining optical fiber 36, so the stress is not circularly symmetrical either. The non-circularly symmetrical stress damages the polarization maintaining performance of the polarization maintaining fiber 36, so it is difficult to make the extinction ratio of the dual fiber collimator 33 very high.

For linearly polarized light incident on a birefringent crystal, when a certain angle is formed between the polarization state of the polarized light and the optical axis of the birefringent crystal, the polarized light will be decomposed into two beams in the birefringent crystal, and the The energy is related to this angle, as shown in Figure 6.

Looking towards the direction of light transmission, assuming that a beam of linearly polarized light is incident on the birefringent crystal at a certain angle θ with the optical axis of the birefringent crystal on the transmission surface, and the energy of the incident beam is P, the incident beam is After reaching the birefringent crystal, it is decomposed into ordinary light o light and extraordinary light e light, and the energy distribution of the two beams is Po and Pe. According to the spectroscopic principle of birefringent crystals, it can be known that

P _o ＝sin ² θ*P (Formula 1) P _e ＝cos ² θ*P (Formula 2)

Therefore, adjusting the angle θ between the polarization state of the beam incident on the birefringent crystal and the optical axis of the birefringent crystal can adjust the energy of the two split beams.

Contents of the invention

The main purpose of the present invention is to provide a polarization splitter and combiner with small volume, low production cost and convenient adjustment of extinction ratio.

Another object of the present invention is to provide a low-cost method for manufacturing a polarization splitter and combiner with small volume and convenient adjustment of extinction ratio.

In order to achieve the above-mentioned main purpose, the polarization splitter and combiner provided by the present invention includes a first single-fiber collimator with a first polarization-maintaining fiber installed, a second single-fiber collimator with a second polarization-maintaining fiber installed, and an installation There is a third single-fiber collimator with a single-mode fiber, and a light-splitting and combining device is provided, and the third single-fiber collimator is located outside the first light transmission surface of the light-splitting and combining device, wherein the first single-fiber collimator A light direction changing device is provided between the light splitter and/or the second single fiber collimator and the second light transmission surface of the light splitting and combining device, and the light direction changing device is provided with at least one reflecting surface.

It can be seen from the above scheme that since at least one of the first single fiber collimator and the second single fiber collimator is provided with a light direction changing device between the second light transmission surface, the light direction changing device can change the propagation direction of the light beam . If the light splitting and combining device is a birefringent crystal, the light direction changing device can increase the distance between the two beams that exit or enter in parallel from the birefringent crystal, reduce the length of the birefringent crystal, and then reduce the polarization of the splitting and combining device. volume, and also reduce production costs. If the light splitting and combining device is a polarization beam splitting prism, the light direction changing device can change the direction of at least one outgoing beam or incident beam, and the axes of all single-fiber collimators can be arranged in parallel, thereby reducing the size of the polarization splitting and combining device. volume of.

Moreover, since the polarization splitter and combiner uses three independent single-fiber collimators, each single-fiber collimator can be rotated conveniently, so that the optical fiber transmission beam in each single-fiber collimator can be independently adjusted. Extinction ratio, the extinction ratio of the polarization splitter and combiner can be made very high, which meets the requirements of modern optical fiber transmission systems.

A preferred solution is that the single-mode fiber installed in the third single-fiber collimator is the third polarization-maintaining fiber. In this way, all the single-mode fibers of the polarization splitter and combiner are polarization-maintaining fibers, which is conducive to maintaining the polarization state of the transmitted light beam, and also facilitates the use of the polarization splitter and combiner as a polarization coupler.

A further solution is that the light-splitting and combining device is a birefringent crystal, the first single-fiber collimator and the second single-fiber collimator are located outside the first side of the birefringent crystal, and the third single-fiber collimator is located outside the birefringent crystal. Outside the second side of the birefringent crystal, the first side and the second side of the birefringent crystal are arranged oppositely, and the light direction changing device is a rhombic prism, and the included angle formed between the first reflection surface and the second light transmission surface of the rhombic prism is is 45°, and the angle formed between the second reflective surface of the rhomboid prism and the axis of the first single-fiber collimator and/or the axis of the second single-fiber collimator is 45°.

It can be seen that among the two parallel beams exiting or entering from the birefringent crystal, at least one beam passes through the rhomboid prism, and the propagation direction of the beam passing through the rhomboid prism remains unchanged but parallel displacement occurs, so that the two single-fiber criteria can be satisfied. The requirements for a larger volume of the straightener, and the need to use a long-length birefringent crystal, reduce the volume of the polarization splitter and combiner.

Another preferred solution is that the light splitting and combining device is a polarization beam splitter prism, the first single fiber collimator and the second single fiber collimator are located outside the first side of the polarization beam splitter prism, and the third single fiber collimator is located outside the polarization beam splitter prism. Outside the second side of the beam-splitting prism, the first side of the polarization beam-splitting prism is opposite to the second side of the polarization beam-splitting prism, and the light direction changing device is a triangular prism, and the reflective surface of the triangular prism is aligned with the axis of the first single fiber collimator. and/or the angle formed between the axes of the second single fiber collimator is 45°.

It can be seen that the outgoing or incident light beams from the polarization splitter prism are reflected by the triangular prism to ensure that the three single-fiber collimators can be arranged parallel to the axes, reducing the volume of the polarization splitter and combiner.

In order to achieve the above-mentioned another purpose, the manufacturing method of the polarization splitter and combiner provided by the present invention includes the first single-fiber collimator equipped with the first polarization-maintaining fiber and the second single-fiber collimator equipped with the second polarization-maintaining fiber The collimator is arranged on the substrate, and a light splitting and combining device is placed on the substrate, and the third single-fiber collimator equipped with a single-mode fiber is placed outside the first light transmission surface of the splitting and combining device, and, on A light direction changing device is arranged between the first single fiber collimator and/or the second single fiber collimator and the second light transmission surface of the light splitting and combining device, the light direction changing device is provided with at least one reflecting surface, and the reflecting The angle formed between the plane and the axis of the first single-fiber collimator and/or the axis of the second single-fiber collimator is 45°, and finally the single fiber is rotated around the axis of the single-fiber collimator with the exit fiber installed The collimator adjusts the extinction ratio of the polarization splitter and combiner.

It can be seen from the above scheme that when manufacturing the polarization splitter and combiner, a light direction conversion device is arranged between at least one of the first single-fiber collimator and the second single-fiber collimator and the second light transmission surface, which can change at least The propagation direction of a beam can increase the distance between two parallel beams, or change the original perpendicular beams to propagate in parallel, so as to reduce the length of birefringent crystals, or make all single-fiber quasi- The axes of the straighteners are arranged in parallel, which reduces the volume of the polarization splitter and combiner, and also reduces its production cost.

In addition, since the polarization beam splitter and combiner does not use a double-fiber collimator, it does not need to consume a lot of time to adjust the double-fiber collimator to meet the requirements of the extinction ratio, and the production process is simple. At the same time, since three independent single-fiber collimators are used, each single-fiber collimator can be rotated independently, so that the extinction ratio of the polarization splitter and combiner can be flexibly and conveniently adjusted.

Description of drawings

FIG. 1 is a schematic structural diagram of a conventional polarization splitter and combiner.

Fig. 2 is a schematic structural diagram of another conventional polarization splitter and combiner.

Fig. 3 is a schematic structural diagram of a third existing polarization splitter and combiner.

Fig. 4 is a schematic structural diagram of a polarization maintaining fiber.

Fig. 5 is a schematic cross-sectional view of a polarization maintaining fiber.

Fig. 6 is a schematic diagram of energy distribution of light components when light passes through a birefringent crystal.

Fig. 7 is a structural principle diagram of the first embodiment of the polarization splitter and combiner of the present invention.

Fig. 8 is an optical path diagram when the first embodiment of the polarization splitter and combiner of the present invention is used as a polarization combiner.

Fig. 9 is a structural principle diagram of the second embodiment of the polarization splitter and combiner of the present invention.

Fig. 10 is a structural principle diagram of the third embodiment of the polarization beam splitter and combiner of the present invention.

Fig. 11 is a structural principle diagram of the fourth embodiment of the polarization splitter and combiner of the present invention.

Fig. 12 is a structural principle diagram of the fifth embodiment of the polarization beam splitter and combiner of the present invention.

Fig. 13 is a structural principle diagram of the sixth embodiment of the polarization beam splitter and combiner of the present invention.

The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

Detailed ways

The polarization beam splitter and combiner of the present invention is used to split or combine polarized light, and can be used as a polarization beam splitter and combiner or as a polarization coupler.

First embodiment:

Referring to Fig. 7, the polarized light splitting and combining device of the present embodiment has a birefringent crystal 40 as a light splitting and combining device, the birefringent crystal 40 has an incident surface 41, and is provided with an outgoing surface 42 opposite and parallel to the incident surface 41, A single-fiber collimator 51 is provided outside the incident surface 41 , and a single-mode optical fiber 52 is installed in the single-fiber collimator 51 . In this embodiment, the single-mode fiber 52 is an ordinary single-mode fiber, not a polarization-maintaining fiber.

Two single-fiber collimators 53, 55 are arranged outside the exit surface 42 of the birefringent crystal 40, and polarization-maintaining optical fibers 54, 56 are respectively installed in the single-fiber collimators 53, 55. It can be seen from Fig. 7 that the axes of the three single-fiber collimators 51, 53, 55 are parallel to each other, and the single-fiber collimator 51 is located outside the side of the birefringent crystal 40, while the single-fiber collimators 53, 55 are located outside the birefringent crystal 40. The other side of the refracting crystal 40 is outside.

A rhombic prism 43 is arranged between the exit surface 42 and the single fiber collimator 55. The rhomboid prism 43 is used as the light direction changing device of this embodiment, and it has two reflective surfaces 44, 45 and two light-transmitting surfaces. 46, 47. The reflective surface 44 and the reflective surface 45 are parallel to each other and form an included angle of 45° with the outgoing surface 42 , and an included angle of 45° is also formed between the reflective surface 45 and the axis of the single fiber collimator 55 . The light-transmitting surfaces 46 and 47 are respectively connected between the two reflecting surfaces 44 and 45 and are parallel to the emitting surface 42 .

In this embodiment, the reflective surfaces 44 and 45 are coated with high-reflective coatings to improve light reflection efficiency, and the light-transmitting surfaces 46 and 47 are coated with anti-reflection coatings.

The light beam L41 exits the single-mode fiber 52 and enters the incident surface 41 of the birefringent crystal 40. The light beam L41 includes light components whose polarization states are perpendicular to each other. The optical axis of the birefringent crystal 40 is shown in FIG. 7 . After the light beam L41 is incident on the birefringent crystal 40, two light beams L42, L43 are formed, and the polarization states of the two light beams L42, L43 are perpendicular to each other. The polarization state of the light beam L42 is perpendicular to the paper, and the polarization state of the light beam L43 is parallel to the paper.

The light beam L42 emerges from the exit surface 42 to form a light beam L44 . The polarization state of the light beam L44 is the same as that of the light beam L42 , and is incident into the polarization-maintaining fiber 54 . The light beam L43 emerges from the emitting surface 42 to form a light beam L45, which is parallel to the light beam L44, and the polarization state of the light beam L45 is the same as that of the light beam L43. The light beam L45 is incident on the reflective surface 44 through the light-transmitting surface 46 of the rhombic prism 43, and is reflected to form a light beam L46. The light beam L46 forms a light beam L47 after passing through the light-transmitting surface 47. In the optical fiber 56. Since the two reflective surfaces 44, 45 of the rhomboid prism 43 form an included angle of 45° with the exit surface 42 and the axis of the single fiber collimator 55, the propagation direction of the light beam L47 is parallel to that of the light beam L44.

In this embodiment, the distance between the light beam L44 and the light beam L45 does not need to be too large, as long as the light spots of the two light beams L44 and L45 do not overlap each other. In this way, the length of the birefringent crystal 40 does not need to be very long, which reduces the volume of the polarization beam splitter and combiner, and also reduces the production cost. Since the light beam L45 will pass through the rhomboid prism 43 to form the light beam L47, the propagation direction of the light beam L47 does not change compared with the light beam L45, but only the distance from the light beam L44 changes, that is, the distance from the light beam L44 increases. In this way, it can ensure that the light beam L44 is incident on the polarization maintaining fiber 53 , and it can also ensure that the light beam L47 is incident on the polarization maintaining fiber 55 .

When manufacturing the polarization beam splitter and combiner, at first arrange single-fiber collimators 53,55 on a substrate, of course, polarization-maintaining optical fibers 54,56 are respectively installed in the single-fiber collimators 53,55, and simultaneously place dual optical fiber collimators on the substrate. For the refraction crystal 40 , the single fiber collimators 53 and 55 are located outside the exit surface 42 of the birefringence crystal 40 . Then, arrange the single-fiber collimator 51 installed with the single-mode fiber 52 on the substrate, so that the single-fiber collimator 51 is located outside the incident surface 41 of the birefringent crystal 40 . Next, a rhomboid prism 43 is placed between the exit surface 42 and the single fiber collimator 55 . Of course, it is necessary to ensure that the angle between the reflection surfaces 44 , 45 of the rhomboid prism 43 and the exit surface 42 is 45°.

After the above devices are arranged, the three single-fiber collimators 51, 53, 55 need to be adjusted. The axis of 55 is perpendicular to the incident surface 41 and ensures a sufficient distance between the single-fiber collimators 53, 55 to receive the light beams L44, L47, respectively.

Of course, the three single-fiber collimators 51, 53, and 55 should be able to rotate freely along their own axes. Since the single-fiber collimators 51, 53, and 55 are all cylindrical, the single-fiber collimators 51, 53,55 are placed on a carriage with a circular turntable. Then, rotate the single-fiber collimators 53 and 55 along their own axes to adjust their extinction ratios. The adjustment of the extinction ratio is to ensure that the polarization states of the light beams L44 and L47 incident on the polarization maintaining fibers 54 and 56 are substantially parallel to the fast axis or the slow axis of the polarization maintaining fibers 54 and 56 . Of course, in practical applications, the extinction ratio can be guaranteed to meet the requirements by changing the accuracy of the angle adjustment fixture or the accuracy of the parameter measuring instrument according to actual needs, because the extinction ratio depends on the polarization state and polarization of the beam incident on the polarization maintaining fiber. The angle between the fast axis or the slow axis of the fiber.

Of course, after placing the above-mentioned devices on the substrate and adjusting the single fiber collimators 51, 53, 55, the substrate and the above-mentioned devices can be packaged in a sealed box to form a complete product for sale.

The use of this embodiment as a polarization beam splitter has been described above. According to the principle of reversible optical paths, this embodiment can also be used as a polarization beam combiner. At this time, the incident surface 41 and the outgoing surface 42 of the birefringent crystal 40 are exchanged, and the original incident fiber becomes the outgoing fiber, and the original outgoing fiber becomes the incident fiber.

Referring to FIG. 8 , the polarization states of the two light beams L51 and L52 emitted from the polarization maintaining fibers 55 and 56 are perpendicular to each other. The light beam L51 is directly incident on the birefringent crystal 40, and the light beam L52 is incident on the reflective surface 45 of the rhombic prism 43 to form the light beam L53, and the light beam L53 is incident to the reflective surface 44 to form the light beam L54, and the light beam L54 is parallel to the light beam L51. Beam L54 is also incident on birefringent crystal 40 forming beam L56.

When the light beams L55 and L56 propagate in the birefringent crystal 40, the distance between the two light beams L55 and L56 is continuously reduced, and they emerge along the same optical path, that is, the combined light beams form the light beam L57, and the light beam L57 is incident on the single-mode optical fiber as the outgoing fiber In the optical fiber 52.

It can be seen that the incident surface 41 and the outgoing surface 42 of the birefringent crystal 40 can be interchanged, so both the incident surface 41 and the outgoing surface 42 are light transmission surfaces.

Since the present embodiment uses the rhombic prism 43 to increase the distance between two parallel light beams, the length of the birefringent crystal 40 does not need to be very long, and the distance between the light beams incident on the polarization-maintaining fibers 54, 56 can also be relatively large. Reduce the volume of the polarization splitter and combiner. In addition, the three single-fiber collimators 51 , 53 , and 55 can rotate around their own axes independently, which is very flexible and convenient to adjust the extinction ratio, and can improve the extinction ratio of the polarization splitter and combiner.

Second embodiment:

Referring to FIG. 9 , the structure of the polarization splitter and combiner of this embodiment is basically the same as that of the first embodiment, except that the polarization-maintaining fiber 60 is installed in the single-fiber collimator 51 instead of an ordinary single-mode fiber. The light beam L61 emitted from the polarization maintaining fiber 60 has a stable polarization state. As shown in FIG. 9 , the angle between the polarization state of the light beam L61 and the paper is θ.

Since the polarization state of the light beam L61 is neither perpendicular nor parallel to the polarization state of the birefringent crystal 40, after the light beam L61 is incident on the birefringent crystal 40, two beams L62 and L63 whose polarization states are perpendicular to each other are formed, and the light beams L62 and L63 The energy of is related to the included angle θ. Therefore, the energy of the two beams L62 and L63 can be adjusted by adjusting the angle θ between the polarization state of the beam L61 and the optical axis of the birefringent crystal 40 .

After the beam L62 emerges from the birefringent crystal 40, it forms the beam L64 and enters the polarization-maintaining optical fiber 54, and the beam L63 emerges from the birefringent crystal 40 to form the beam L65, and the beam L65 passes through the reflective surface 44 of the rhombic prism 43 to form a beam L66 , the light beam L66 passes through the reflective surface 45 to form a light beam L67 parallel to the light beam L64 , and finally the light beam L67 is incident into the polarization-maintaining optical fiber 56 . In this way, the polarization beam splitter and combiner of this embodiment can be used as a polarization coupler, that is, it can distribute the energy of the two beams divided by the incident beam.

According to the principle of reversibility of the optical path, this embodiment can also be used as a light combining device, and the specific optical path will not be described in detail.

Since this embodiment also increases the distance between the two parallel light beams through the rhombic prism 43, in the case of using a shorter birefringent crystal 40, the two beams are respectively incident on the two single optical fibers for collimation. Requirements of the device, reducing the volume of the polarization splitter and combiner, is also conducive to the adjustment of the extinction ratio.

The method for manufacturing the polarization splitter and combiner of the present embodiment is basically the same as that of the first embodiment, except that the polarization-maintaining fiber 60 is installed in the single-fiber collimator 51 instead of a common single-mode fiber, and other steps are the same, no longer repeat.

Third embodiment:

Referring to FIG. 10 , this embodiment has a polarizing beam splitting prism 70 . The polarizing beam splitting prism 70 is used as a light splitting and combining device, has a beam splitting film 71 , and has an incident surface 72 and outgoing surfaces 73 and 74 . Since the light path is reversible, the outgoing surface 72 and the outgoing surfaces 73 and 74 can be exchanged with each other, so the incident surface 72 and the outgoing surfaces 73 and 74 are both light transmission surfaces.

The single-fiber collimator 81 is located outside the incident surface 72 , and a single-mode optical fiber 82 is installed in the single-fiber collimator 81 . The single-fiber collimators 83 and 85 are both located outside the exit surface 74 , and polarization-maintaining fibers 84 and 86 are respectively installed in the single-fiber collimators 83 and 85 . In this embodiment, the axes of the single fiber collimators 81, 83, 85 are parallel to each other.

A triangular prism 76 as a light direction conversion device is arranged outside the exit surface 73. The triangular prism 76 has a reflective surface 77 and two light-transmitting surfaces 78, 79. An angle of 45° is formed between the reflective surface 77 and the exit surface 73. An included angle of 45° is also formed between the reflective surface 77 and the axis of the single fiber collimator 83 . The reflective surface 77 is coated with a high-reflection film, and the light-transmitting surfaces 78 and 79 are coated with an anti-reflection film.

In this embodiment, the incident surface 72 is the first type of light transmission surface, and the light beam L71 emitted from the single-mode fiber 82 enters the polarization beam splitter prism 70 through the incident surface 72 . The light beam L71 includes two light components whose polarization states are perpendicular to each other, and after the light beam L71 is incident on the beam splitting film 72, a reflected light beam L72 and a transmitted light beam L73 are formed respectively, the reflected light beam L72 exits through the exit surface 73, and the light beam L73 passes through the exit surface 74 shoot. In this embodiment, both the outgoing surfaces 73 and 74 are second-type light transmission surfaces.

The polarization state of the light beam L73 is fixed, that is, parallel to the paper surface, and enters the polarization-maintaining optical fiber 86 after exiting the exit surface 74 . The polarization state of the light beam L72 is perpendicular to the polarization state of the light beam L73 , and the light beam L74 is formed after entering the reflective surface 77 of the triangular prism 76 . It can be seen from FIG. 10 that the light beam L74 is parallel to the light beam L73. Therefore, the triangular prism 76 changes the light beam L72 that is originally perpendicular to the propagation direction of the light beam L73 into a light beam L74 that is parallel to the propagation direction of the light beam L73. In this way, the single-fiber collimators 83 and 85 can be arranged parallel to each other to reduce the volume of the polarization splitter and combiner.

When manufacturing the polarization splitting light combiner, the single-fiber collimator 81 installed with the single-mode fiber 82 and the single-fiber collimator 83, 85 installed with the polarization-maintaining optical fiber 84, 86 are placed on a substrate, and on the substrate Place the polarization beam splitting prism 70 on it, so that the single fiber collimator 81 is located outside one side of the polarization beam splitting prism 70, and the single fiber collimators 83, 85 are located outside the other side of the polarization beam splitting prism 70.

Then, a triangular prism 76 is arranged outside the emitting surface 73 , so that an included angle of 45° is formed between the reflecting surface 77 of the triangular prism 76 and the emitting surface 73 . Finally, it is necessary to adjust the single-fiber collimators 81, 83, and 85, including adjusting their positions and angles, to ensure that the axes of the single-fiber collimators 81, 83, and 85 are all perpendicular to the incident surface 72, and that the single-fiber collimators The axis of 81 is on the same line as the axis of the single fiber collimator 85, and the angle between the axis of the single fiber collimator 83 and the reflecting surface 77 is 45°, while ensuring that the polarization maintaining fiber 84 can receive the light beam L74.

In order to adjust the extinction ratio of the polarization splitter and combiner, the three single fiber collimators 81, 83, 85 should be able to rotate around their own axes. If it is desired that the polarization splitter and combiner have a higher extinction ratio, the polarization states of the light beams L74 and L73 incident on the polarization maintaining fibers 84 and 86 can be adjusted to be substantially parallel to the fast axis or the slow axis of the polarization maintaining fibers 84 and 86 . In this way, the extinction ratio of the polarization splitter and combiner can be flexibly adjusted, and the extinction ratio of the polarization splitter and combiner can be made very high, meeting the requirements of modern optical fiber transmission systems.

Fourth embodiment:

Referring to Fig. 11, the structure of the polarization splitter and combiner of this embodiment is basically the same as that of the third embodiment, except that what is installed in the single-fiber collimator 81 is not an ordinary single-mode fiber, but a polarization-maintaining fiber 87. From the polarization-maintaining fiber The polarization state of the light beam L81 emitted by 87 is fixed, and the angle formed between it and the paper surface is θ. In this way, the energy of the beams L82 and L83 formed after the beam L81 is incident on the beam splitting film 71 is related to the angle θ. By adjusting the angle θ, the energy of the beams L82 and L83 can be adjusted, thereby realizing the polarization coupling of the beams.

The light beam L83 emerges from the polarization beam splitter 70 and then enters the polarization maintaining fiber 86 .

The steps of manufacturing the polarization splitter and combiner are basically the same as those in the third embodiment, except that the ordinary single-mode fiber installed in the single-fiber collimator 81 is changed to a polarization-maintaining fiber 87 .

Fifth embodiment:

Referring to Fig. 12, the polarization beam splitting and combining device of the present embodiment has a polarization beam splitting prism 101 as a light splitting and combining device, and a beam splitting film 102 is arranged in the polarization beam splitting prism 101, and an incident surface 103 and an outgoing surface 104, 105 are provided. In the embodiment, both the incident surface 103 and the outgoing surfaces 104 and 105 are light transmission surfaces, and the incident surface 103 is the first type of light exiting surface, while the exiting surfaces 104 and 105 are the second type of light transmission surfaces.

Three single-fiber collimators 121, 123, and 125 are arranged outside the same side of the polarization beam splitter 101, and single-mode optical fibers 122 and polarization-maintaining optical fibers 124, 126 are respectively installed in the three single-fiber collimators 121, 123, and 125. . The single fiber collimator 121 is located outside the incident surface 103 and emits the light beam L91 to the polarization beam splitter prism 101 .

A triangular prism 106 as a light direction conversion device is arranged outside the exit surface 105, and an included angle of 45° is formed between the reflective surface 107 of the triangular prism 106 and the exit surface 105, and forms an angle with the axis of the single fiber collimator 125. 45° included angle. In this embodiment, a high-reflection film is coated on the reflective surface 107 , and an anti-reflection film is coated on the light-transmitting surfaces 108 and 109 .

A triangular prism 110 is also arranged outside the exit surface 104. The triangular prism 110 has two reflective surfaces 111, 112 and a light-transmitting surface 113 perpendicular to each other. Anti-reflection coating is coated on it. An included angle of 45° is formed between the reflecting surface 111 and the outgoing surface 104 , and an included angle of 45° is also formed between the reflecting surface 112 and the axis of the single fiber collimator 123 .

The light beam L91 includes two light components whose polarization states are perpendicular to each other, and after exiting the single-mode fiber 122, it is divided into two light beams L92 and L93 whose polarization states are perpendicular to each other on the beam splitting film 102, and the light beam L92 is reflected by the reflecting surface 111 to form a light beam L94 , the light beam L94 is reflected by the reflective surface 112 to form a light beam L95 , and the light beam L95 is incident into the polarization-maintaining optical fiber 124 . The light beam L93 is reflected by the reflective surface 107 to form a light beam L96 , and the light beam L96 is parallel to the light beam L95 , and the light beam L96 is incident into the polarization-maintaining optical fiber 126 .

This embodiment is a reflective polarization light splitter and combiner, which respectively reflect two outgoing light beams through two triangular prisms 106 and 110 to ensure that the polarization-maintaining optical fibers 124 and 126 as outgoing optical fibers and the single-mode optical fiber 122 as incident optical fibers are located at On the same side of the polarization beam splitter and combiner, and the axes of the three single fiber collimators 121, 123, 125 are parallel to each other, which is beneficial to the packaging and use of the polarization beam splitter and combiner.

In addition, since the three single-fiber collimators 121, 123, and 125 are arranged in parallel, the volume of the polarization splitter and combiner can be reduced. And the three single-fiber collimators 121, 123, 125 should be able to rotate freely around their own axes, so as to conveniently adjust the extinction ratio of the polarization splitter and combiner.

When manufacturing the polarization splitter and combiner, first the single-fiber collimator 121 with the single-mode fiber 122 installed, the single-fiber collimator 123, 125 with the polarization-maintaining optical fiber 124, 126 installed on the substrate, and on the substrate A polarization beam splitter 101 is placed, a triangular prism 106 is placed outside the exit surface 104 of the polarization beam splitter prism 101 , and a triangular prism 110 is placed outside the exit surface 105 . Of course, the angles of the reflective surfaces of the triangular prisms 106 and 110 need to meet the aforementioned requirements.

Then, the positions and angles of the single-fiber collimators 121 , 123 , and 125 are adjusted so that the axes of the three single-fiber collimators 121 , 123 , and 125 are all perpendicular to the incident plane 103 . Finally, the single-fiber collimators 123 and 125 are rotated around their own axes, thereby adjusting the extinction ratio of the polarization splitter and combiner.

Sixth embodiment:

Referring to Fig. 13, the polarization splitting and combining device of the present embodiment has a polarization splitting prism 130 as a light splitting and combining device, and is provided with a triangular prism 136, and is provided with three single fiber collimators 141 outside the same side of the polarization splitting prism 130 .

The polarization splitting prism 130 has a splitting film 131 , two light transmission surfaces 132 , 133 , and a light reflection surface 134 . The triangular prism 136 has a reflective surface 137 and two light-transmitting surfaces 138, 139, an included angle of 45° is formed between the reflective surface 137 and the light transmission surface 133, and an angle between the reflective surface 137 and the axis of the single fiber collimator 143 is also Form an included angle of 45°.

The light beam L131 emitted from the single-mode fiber 142 includes two light components whose polarization states are perpendicular to each other. The light beam L131 is incident on the beam splitting film 131 and then split into two light beams L132 and L133 whose polarization states are perpendicular to each other. The light beam L132 is formed after being reflected by the reflective surface 134 The light beam L134 forms a light beam L135 after passing through the reflective surface 137 , and the light beam L135 is incident into the polarization-maintaining optical fiber 144 . The light beam L133 passes through the reflective surface 134 to form a light beam L136 , the light beam L136 is parallel to the light beam L135 , and the light beam L136 is incident into the polarization-maintaining fiber 146 .

When manufacturing the polarization splitter and combiner, at first the single-fiber collimator 141 with the single-mode fiber 142 installed, the single-fiber collimator 143,145 with the polarization-maintaining fiber 144,146 installed on the substrate, and on the substrate The polarization beam splitting prism 130 is placed, and the three single fiber collimators 141 , 143 , 145 are located on the same side of the polarization beam splitting prism 130 . Of course, when placing the single-fiber collimators 141, 143, 145, it is necessary to ensure that each single-fiber collimator 141, 143, 145 can rotate around its own axis. Then, a triangular prism 136 is arranged outside the light transmission surface 133 of the polarization splitter prism 130 to ensure that an included angle of 45° is formed between the reflection surface 137 of the triangular prism 136 and the light transmission surface 133 .

Next, adjust the angles and positions of the three single fiber collimators 141 , 143 , 145 to ensure that the axes of the single fiber collimators 141 , 143 , 145 are parallel to each other and perpendicular to the light transmission surface 132 . Finally, the single-fiber collimators 143 and 145 are rotated around their own axes to adjust the extinction ratio of the polarization splitter and combiner.

It can be seen from the above-mentioned multiple embodiments that the present invention mainly arranges a light direction conversion device outside the light transmission surface of the light splitting and combining device, such as a rhomboid prism or a triangular prism, to change the propagation direction of the light, thereby ensuring that the incident light beam is consistent with the outgoing light beam. The beams are parallel, and there is a large distance between the two incident beams or the two outgoing beams, which meets the requirement that each beam can be incident on a polarization-maintaining fiber, and each single-mode fiber or polarization-maintaining fiber Both are installed in an independent single-fiber collimator, and the extinction ratio of the polarization splitting and combining device can be conveniently adjusted by rotating the single-fiber collimator around its own axis. In this way, the volume of the polarization splitter and combiner can be made smaller, and the production process is simple, the adjustment of the extinction ratio is flexible and convenient, and the extinction ratio can be adjusted to a high level, which meets the working needs of the modern optical fiber network transmission system.

In addition, the fifth embodiment and the sixth embodiment can also make polarization couplers by changing the common single-mode optical fibers 122 , 142 installed in the single-fiber collimators 121 , 141 into polarization-maintaining optical fibers.

Of course, the above scheme is only a preferred implementation mode of the present invention, and there are more changes in actual application. For example, all the above-mentioned embodiments can be used as polarization splitting devices or as polarization combining devices. This is based on the optical path Determined by the principle of reversibility; as another example, in the first embodiment and the second embodiment, two rhombic prisms can be set outside the exit surface of the birefringent crystal, and each beam emitted from the birefringent crystal passes through a rhombic Prisms, changes like this can also achieve the purpose of the present invention, and such changes should also be included in the protection scope of the claims of the present invention.

Claims (10)

1. the polarization spectro splicer comprises

The first single fiber collimating apparatus of first polarization maintaining optical fibre, the 3rd single fiber collimating apparatus that the second single fiber collimating apparatus of second polarization maintaining optical fibre is installed and single-mode fiber is installed are installed; And being provided with a beam split splicer spare, said the 3rd single fiber collimating apparatus is positioned at outside the first light transmission face of said beam split splicer spare;

It is characterized in that:

Be provided with the light direction transformation device between the second light transmission face of the said first single fiber collimating apparatus and/or said second single fiber collimating apparatus and said beam split splicer spare, said light direction transformation device is provided with at least one reflecting surface.

2. polarization spectro splicer according to claim 1 is characterized in that:

Said single-mode fiber is the 3rd polarization maintaining optical fibre.

3. polarization spectro splicer according to claim 1 and 2 is characterized in that:

Said beam split splicer spare is a birefringece crystal; Said first single fiber collimating apparatus and the said second single fiber collimating apparatus are positioned at outside first side of said birefringece crystal; Said the 3rd single fiber collimating apparatus is positioned at outside second side of said birefringece crystal, and first side of said birefringece crystal and second side of said birefringece crystal are oppositely arranged.

4. polarization spectro splicer according to claim 3 is characterized in that:

Said light direction transformation device is a rhombic prism; The angle that forms between first reflecting surface of said rhombic prism and the said second light transmission face is 45 °, and the angle that forms between the axis of second reflecting surface of said rhombic prism and the axis of the said first single fiber collimating apparatus and/or the said second single fiber collimating apparatus is 45 °.

5. polarization spectro splicer according to claim 1 and 2 is characterized in that:

Said beam split splicer spare is a polarization splitting prism; Said first single fiber collimating apparatus and the said second single fiber collimating apparatus are positioned at outside first side of said polarization splitting prism; Said the 3rd single fiber collimating apparatus is positioned at outside second side of said polarization splitting prism, and first side of said polarization splitting prism and second side of said polarization splitting prism are oppositely arranged.

6. polarization spectro splicer according to claim 5 is characterized in that:

Said light direction transformation device is a triangular prism; The angle that forms between the axis of the axis of the reflecting surface of said triangular prism and the said first single fiber collimating apparatus and/or the said second single fiber collimating apparatus is 45 °, and the angle that forms between the reflecting surface of said triangular prism and the said second light transmission face is 45 °.

7. polarization spectro splicer according to claim 1 and 2 is characterized in that:

Said beam split splicer spare is a polarization splitting prism, and the said first single fiber collimating apparatus, the said second single fiber collimating apparatus and said the 3rd single fiber collimating apparatus all are positioned at outside the same side of said polarization splitting prism;

Said light direction transformation device is a triangular prism; The angle that forms between the axis of the reflecting surface of said triangular prism and the said first single fiber collimating apparatus is 45 °; The angle that forms between the axis of the reflecting surface of said triangular prism and the said second single fiber collimating apparatus also is 45 °, and the angle that forms between the reflecting surface of said triangular prism and the said second light transmission face is 45 °.

8. the manufacturing approach of polarization spectro splicer comprises

With the first single fiber collimating apparatus that first polarization maintaining optical fibre is installed and the second single fiber collimator arrangement that second polarization maintaining optical fibre is installed on substrate; And on said substrate, place a beam split splicer spare, the 3rd single fiber collimating apparatus that single-mode fiber is installed is placed on outside the first light transmission face of said beam split splicer spare;

It is characterized in that:

Between the second light transmission face of the said first single fiber collimating apparatus and/or said second single fiber collimating apparatus and said beam split splicer spare, the light direction transformation device is set; Said light direction transformation device is provided with at least one reflecting surface, and the angle that forms between the axis of the axis of said reflecting surface and the said first single fiber collimating apparatus and/or the said second single fiber collimating apparatus is 45 °;

Axis around the single fiber collimating apparatus that outgoing optical fiber is installed rotates said single fiber collimating apparatus.

9. the manufacturing approach of polarization spectro splicer according to claim 8 is characterized in that:

Said single-mode fiber is the 3rd polarization maintaining optical fibre.

10. it is characterized in that according to Claim 8 or the manufacturing approach of 9 described polarization spectro splicers:

Said beam split splicer spare is birefringece crystal or polarization splitting prism, and said light direction transformation device is rhombic prism or triangular prism.

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