JP2000249874A - Optical transceiver module - Google Patents

Abstract

(57) [Problem] To provide an optical transmission / reception module which can be manufactured in bulk by a semiconductor process or the like and can be easily connected to an optical fiber. SOLUTION: An optical waveguide also formed on a substrate so as to match an optical fiber held in an optical fiber guide groove formed on the substrate, and the optical waveguide for demultiplexing light passing through the optical waveguide. By using a structure in which an optical fiber is connected to a light receiving element and a light emitting element disposed on a substrate via an optical filter disposed therein, a large number of optical transmitting and receiving modules can be manufactured collectively by a semiconductor process or the like. At the same time, connection with an optical fiber becomes easy. Also,
By patterning the guide groove and the optical waveguide in the same step, the alignment between the optical fiber and the optical waveguide can be easily and accurately performed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical transmission / reception module used for optical communication, optical signal processing, etc., for converting an optical signal into an electric signal.

[0002]

2. Description of the Related Art Conventionally, bidirectional optical communication using optical fibers has been frequently used in communication equipment, audio equipment, and the like. Generally, a high-speed modulated optical signal is transmitted through an optical fiber. In order to convert this into finally necessary information such as audio and video, it is converted into an electric signal and further converted into audio and video data. Thus, the required output can be obtained. Various methods and optical transmission / reception modules have been proposed. For example, JP-A-8-190026 discloses that a waveguide and a semiconductor device platform are formed on a silicon substrate, and a filter, a laser diode (light-emitting device),
A module mounting a photodiode (light receiving element) and the like is disclosed. Since this module is formed on a substrate by using a process similar to that of a semiconductor device, there is an advantage that a large number of modules can be collectively formed on a wafer.

[0003]

However, in the above-described module for forming a waveguide on a substrate, when connecting to an optical fiber, a separate component holding an optical fiber end, such as a fiber array, is prepared and highly accurate. The connection has to be performed using the alignment technique, and the operation is complicated. In fact,
Optical axis adjustment requires accuracy higher than ± 0.5 μm,
It is a very cumbersome task.

Therefore, for example, Japanese Patent Application Laid-Open No. 10-197762
In Japanese Patent Application Laid-Open Publication No. H10-157, a module in which an optical fiber is directly assembled to a substrate without using a waveguide is also proposed. In the case of this module, there is an advantage that a high-precision alignment operation can be omitted because it is not necessary to separately connect the optical fiber.

[0005] However, since the optical fiber is already incorporated in a state where the module is assembled and mounted, not only may the fiber be erroneously damaged during the process, but also the optical fiber protrudes from the module. In addition, there is a problem that assembly must be performed individually, a large space is required, and collective processing such as a case of forming a waveguide on a substrate cannot be performed at a time.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems of the prior art, and provides an optical transmitting / receiving module which can be manufactured in large numbers by a semiconductor process or the like and can be easily connected to an optical fiber. The purpose is to:

[0007]

SUMMARY OF THE INVENTION According to the present invention, there is provided an optical transceiver module for transmitting and receiving optical signals transmitted by an optical fiber. An optical fiber guide groove formed on a substrate made of silicon (Si), a light receiving element and a light emitting element disposed on the substrate, and aligned with an end of an optical fiber guided by the optical fiber guide groove. An optical waveguide formed on the substrate, and an optical filter disposed in the optical waveguide on the substrate to split light passing through the optical waveguide. Is achieved by providing
In particular, the optical filter is inserted into a slit formed obliquely in the optical waveguide on the substrate, and reflects light of a specific wavelength toward a light receiving element on the substrate or from a light emitting element on the substrate. The light may be reflected toward the optical fiber via the optical waveguide, and the substrate may be adjusted to adjust an interval between the optical filter and the light receiving element or the light emitting element as necessary. A perforated spacer may be provided between the light receiving element and the light emitting element.

[0008]

Preferred embodiments of the present invention will be described below in detail with reference to the accompanying drawings.

FIG. 1 is a perspective view of an optical transceiver module to which the present invention is applied, and FIG. 2 is a sectional view thereof. This optical transmitting / receiving module includes a connection unit 2 for connecting to an optical fiber, a reception unit 3
And the transmitting section 4 are formed on the same substrate 1 made of quartz or silicon.

The optical fiber connecting portion 2 comprises a guide groove 5 having a V-shaped cross section formed in front of a step portion 1a provided on the substrate 1, and an optical fiber F from the outside is inserted into the guide groove 5.
To receive and hold the tip.

The receiving section 3 includes an optical waveguide 6 penetrating through the stepped portion 1a of the substrate 1 so as to coincide with the axis of the optical fiber F held in the guide groove 5, and specifies the light passing through the waveguide 6. A reflection type filter 7 is inserted obliquely in the middle of the optical waveguide 6 so as to reflect only the wavelength (for example, 1.55 μm) component obliquely upward in the drawing, and receives the light reflected by the filter 7. And a photodiode 8 as a light receiving element provided on the step portion 1a in order to perform the operation.

The transmitting section 4 includes a laser diode 9 as a light emitting element provided on the side opposite to the optical fiber F with the step section 1a interposed therebetween, that is, behind the step section 1a so as to face the end of the optical waveguide 6. And a monitoring photodiode 10 for monitoring the output of the laser diode 9.

Hereinafter, a description will be given of a manufacturing procedure of the above-mentioned optical transceiver module. First, a step (platform) is formed on a quartz substrate or a silicon wafer by etching or machining. Next, a lower cladding layer 6a of SiO ₂ or the like is formed by a film forming method such as a CVD method, and is planarized by polishing or etching to a predetermined thickness.

Next, a core layer 6b is formed on the lower cladding layer 6a.
Is formed. Here, the core layer 6b has a refractive index slightly higher than that of the lower cladding layer 6a and the upper cladding layer 6c described later in order to propagate light of a communication wavelength.
It is generally known to add a small amount of an element such as Ge or Ti in order to increase the refractive index similarly to the optical fiber.

Next, in order to form a path of the optical waveguide, that is, a core pattern, a resist is formed using a prepared photomask, and then the core layer 6b is etched (photolithography). Here, RIE (reactive ion etching) is preferably used for the etching. At this time, by forming a pattern for forming the V-shaped guide groove 5 serving as a reference for positioning the optical waveguide 6 and the optical fiber F on the photomask, the resist can be simultaneously formed. it can. For this reason, the relative displacement between the core layer 6b of the optical waveguide 6 and the optical fiber guide groove 5 does not substantially occur because the same photomask is used. still,
For example, in the case of a silicon substrate, the guide groove 5 is formed by anisotropic etching using an alkaline solution such as KOH. Then, an SiO ₂ film is formed as the upper cladding layer 6c, and the embedded optical waveguide 6 is completed.

Thereafter, the upper clad layer 6c is flattened, and the unnecessarily formed upper clad layer, core, lower clad layer and the like are removed to expose the substrate surface before and after the step 1a. Then, an electrode pattern, a wiring pattern, or the like of Au, Al, or the like is formed on the substrate or the upper clad layer 6c as necessary, and the electrodes are dipped with solder.

Next, a groove 11 for inserting the filter 7 and a groove 12 for abutting the optical fiber F against the optical waveguide 6 are formed by dicing or etching. Here, the groove 11 for inserting the filter 7 is not perpendicular to the surface of the substrate but is formed obliquely at an angle θ of, for example, 8 ° to 30 °, corresponding to the reflection direction of the filter 7. The groove 12 is formed perpendicular to the substrate so that the end face of the optical fiber F and the end face of the optical waveguide 6 face each other.

Next, the laser diode 9, the photodiodes 8, 10, and other semiconductor elements (not shown) are mounted at predetermined positions by soldering, and the filter 7 is inserted into the groove 11, and an adhesive is put therein and cured. Here, it is conceivable that both may interfere depending on the position and size of the filter 7 and the photodiode 8. Therefore, an unnecessary portion of the filter 7 may be removed as shown in FIG. 3, and as shown in FIG.
, The light receiving position can be adjusted without removing unnecessary portions of the filter 7. If the spacer 13 itself or its surface is made conductive, electrical connection with the substrate 1 is also possible. Spacer 13 used
Is formed with a hole or a groove 13a for securing an optical path in the center portion, and examples of the material include a thin plate of a metal such as phosphor bronze or stainless steel, which is plated with gold. Also,
When the spacer 13 is interposed, the light path becomes longer from the optical waveguide 6 to the photodiode 8, so that the beam spread increases and the light receiving efficiency may decrease. , The thickness of the spacer 13 is set to 100 μm to 300 μm.
There is no problem if it is within the range.

Finally, the substrates are cut one by one, and the optical fiber F is assembled into the guide groove 5, whereby the optical transceiver module is completed.

The operation of the optical transceiver module according to the present invention will be described below with reference to FIG. This optical transceiver module converts an optical signal sent from the optical fiber F into an electric signal, or converts an electric signal from a telephone or the like into an optical signal and sends it to the optical fiber F.

An optical signal from the outside enters the waveguide 6 from the optical fiber F, and only a component of the wavelength λ2 (for example, 1.55 μm) is reflected by the filter 7 inserted in the optical waveguide 6. Then, the reflected light passes through the optical waveguide 6 and exits to the surface side of the substrate 1. Then, the light is received by the photodiode 8 provided at the emission position, converted into an electric signal, and a predetermined output is obtained. Here, for efficient reception, it is necessary to match the beam center of the reflected light of the filter 7 with the center of the light receiving portion of the photodiode 8, and for this purpose, the optical fiber F and the optical waveguide 6 are precisely aligned. Although it is necessary to align the optical fiber, in the optical transceiver module according to the present invention, the optical fiber F guided by the guide groove 5 and the optical waveguide 6 are aligned with high precision as described above. It is possible to guide the light to the light receiving element (photodiode) without loss of the reflected light by the filter 7 while easily realizing the high-precision connection with the filter 7.

On the other hand, a wavelength λ1 (for example, 1.30) obtained by converting a predetermined electric signal emitted from the laser diode 9
μm) enters the optical waveguide 6, passes through the filter 7 as it is, enters the optical fiber F from the optical waveguide 6, and sends out a necessary signal.

In order to transmit and receive light to and from such an optical transmitting and receiving module, a wavelength λ1 (1.30 μm) having a similar structure is used.
m) a photodiode for receiving the light as a light receiving element;
What is necessary is just to prepare an optical transmitting and receiving module having a laser diode for transmitting light of wavelength λ2 (1.55 μm) as a light emitting element and a filter for reflecting light of wavelength λ2 (1.55 μm).

Incidentally, for example, the filter 7 having the same structure as described above is used.
Instead, a half mirror having a ratio of reflection to transmission of about 5: 5 to 6: 4 is inserted into the groove 11, and the light emitting element and the light receiving element emit and receive light of the same wavelength, and the transmission and reception thereof are performed. Is performed in time so that signals do not collide, bidirectional transmission of light of the same wavelength is possible with one type of optical transceiver module.

Further, in this configuration, the light from the light emitting element is transmitted through the filter and the half mirror, and the light reflected by the filter and the half mirror is received by the light receiving element. .

[0026]

As is apparent from the above description, according to the optical transceiver module of the present invention, the optical transceiver module is also formed on the substrate so as to match the optical fiber held in the optical fiber guide groove formed on the substrate. A structure in which an optical fiber is connected to a light receiving element and a light emitting element disposed on a substrate via an optical filter disposed in the optical waveguide in order to demultiplex the light passing through the optical waveguide and the light passing through the optical waveguide. By doing so, a large number of optical transmission / reception modules can be manufactured collectively by a semiconductor process or the like, and connection with an optical fiber becomes easy. Further, by patterning the guide groove and the optical waveguide in the same step, the alignment between the optical fiber and the optical waveguide can be easily and accurately performed. Furthermore,
An optical filter is inserted into a slit formed obliquely in an optical waveguide on a substrate, and light of a specific wavelength is reflected toward a light receiving element on the substrate or light from a light emitting element on the substrate is transmitted through the optical waveguide. By adopting a configuration in which light is reflected toward the fiber, a general surface light receiving type that does not require high positioning accuracy can be used as the photodiode as the light receiving element. In addition, by providing a perforated spacer between the substrate and the light receiving element or the light emitting element to adjust the distance between the optical filter and the light receiving element or the light emitting element as necessary, the filter, the light receiving element or the light emitting element is provided. Irrespective of the size and arrangement, the light receiving or light emitting position can be adjusted without processing them, so that versatility is improved and assembly is simplified.

[Brief description of the drawings]

FIG. 1 is a perspective view of an optical transceiver module to which the present invention is applied.

FIG. 2 is a sectional view of FIG.

FIG. 3 is an enlarged view of a main part of FIG. 2;

FIG. 4 is a view similar to FIG. 3, showing a modification of the optical transceiver module to which the present invention is applied;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Substrate 1a Step part 2 Connection part 3 Receiving part 4 Transmitting part 5 Guide groove 6 Optical waveguide 6a Lower clad layer 6b Core layer 6c Upper clad layer 7 Reflection filter 8 Photodiode 9 Laser diode 10 Monitoring photodiode 11, 12 Groove 13 Spacer 13a Hole or groove F Optical fiber

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Yutaka Natsume 3-10-10, Fukuura, Kanazawa-ku, Yokohama-shi, Kanagawa Prefecture Inside Japan Co., Ltd. (72) Inventor Takayuki Senda 3--10, Fukuura, Kanazawa-ku, Yokohama-shi, Kanagawa Japan Co., Ltd. (72) Inventor Shigeru Kawaguchi 3-10-10 Fukuura, Kanazawa-ku, Yokohama-shi, Kanagawa Japan F-term (reference) 2H037 AA01 BA02 BA11 BA24 CA00 CA34 CA37 DA03 DA04 DA06 DA12 5F073 BA01 FA06

Claims (3)

[Claims] 1. An optical transceiver module for transmitting and receiving an optical signal transmitted by an optical fiber, wherein the optical fiber guide is formed on a substrate made of quartz or silicon (Si) to guide an end of the optical fiber. A groove; a light receiving element and a light emitting element disposed on the substrate; an optical waveguide formed on the substrate so as to match an end of an optical fiber guided by the optical fiber guide groove; and the optical waveguide An optical filter disposed in the optical waveguide on the substrate so as to split light passing through the optical transceiver. 2. The optical filter is inserted into a slit formed obliquely in the optical waveguide on the substrate,
A light of a specific wavelength is reflected toward a light receiving element on the substrate or light from a light emitting element on the substrate is reflected toward the optical fiber through the optical waveguide. The optical transceiver module according to claim 1. 3. A perforated spacer is provided between the substrate and the light receiving element or the light emitting element for adjusting a distance between the optical filter and the light receiving element or the light emitting element. The optical transceiver module according to claim 1 or 2, wherein