JPS6146911A - Waveguide type optical module - Google Patents

Abstract

PURPOSE:To make a titled module small in size by providing a photodetector and a light emitting element brought to bonding on a silicon substrate, and an optical fiber connected to other end face of an optical waveguide. CONSTITUTION:A waveguide type optical module is operated by applying a driving current to a semiconductor laser 3 and oscillating it. Signal light from the semiconductor laser 3 is led to a quartz compound glass optical waveguide 2 through an end face 2a, and led into an optical fiber 5 through an end face 2c. On the contrary, signal light from the optical fiber 5 is led to the quartz compound glass optical waveguide 2 through the end face 2c, and a part of said light is detected by a photodetector 4 through a Y-shaped branching part and an end face 2b. In this regard, the semiconductor laser 3 is accompanied with heating, but it is radiated on a silicon substrate 1 having good thermal conductivity, therefore, the continuous operation can be executed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a highly productive modular optical component used in the field of optical communications.

[Conventional technology]

In recent years, with the progress of optical communications, there has been a need to supply optical parts such as optical branching/coupling circuits and optical demultiplexing/combining devices in large quantities and at low cost. Conventionally, these optical components are
Bulk optical components consisting of combinations of prisms, lenses, or filters were used. However, these bulk type optical components require a long time to assemble and adjust, resulting in poor productivity, resulting in high prices for optical components, and difficulty in miniaturizing them, which has hindered their development into various fields of optical communication systems. was being inhibited.

As a way to solve the above problem, attempts have been made to realize planar core waveform optical components, that is, optical IC type optical components.
It was difficult to connect optical waveguides with different film thicknesses at the front and back and optical fibers, and this method was still beyond the realm of proof of principle, and had not been put to practical use.

Therefore, attempts have been made to reduce the size and cost by adopting an integrated module structure that combines miniaturized prisms and lenses with light receiving and emitting elements. Therefore, there is no substitute for the fact that assembly requires precise positioning, and it could not be a comprehensive solution.

[Purpose of the invention]

The present invention was made in order to solve the above-mentioned drawbacks of conventional optical components, and provides a four-wave optical module that can achieve high productivity (and therefore, low price) and miniaturization. The purpose is to provide.

(Structure of the Invention) A waveguide optical module according to the present invention includes a silica-based glass optical waveguide formed on a silicon substrate, and optically coupled to mutually different end faces of the optical waveguide, each of which is bonded onto the silicon substrate. It is characterized by comprising a receiving/emitting element and an optical fiber connected to another end face of the optical waveguide.

In the above configuration, when aligning the optical axes of the optical waveguide and the receiving/emitting element or the optical fiber, X, Y
, it is necessary to perform alignment in the 3-axis direction of the Z axis,
Regarding the optical axis direction, this can be easily done because it is sufficient to simply bring the receiving/emitting element or the optical fiber into contact with the end face of the optical waveguide. Furthermore, alignment of the silicon substrate in the vertical direction can also be easily performed by making the dimensions of the receiving/emitting element or the optical fiber correspond to the thickness of the optical waveguide.

After all, in the above configuration, when aligning the optical waveguide and the receiving/emitting element or the optical fiber,
Because it is only necessary to perform accurate positioning in one of the three Z-axis directions, it is possible to perform accurate positioning in all three axes like conventional bulk optical components. In comparison, alignment can be easily performed.

Furthermore, since no lenses, prisms, etc. are used, the device can of course be made smaller. ([Embodiment] Fig. 1 is a diagram showing an embodiment of the waveguide optical module of the present invention configured for bidirectional optical communication. In the figure, reference numeral 1 is a silicon substrate, and 2 is a quartz-based glass substrate. Optical waveguide, 3 is a semiconductor laser (light emitting element), 4 is a light receiving element, 5
is an optical fiber, 6 is a guide for a half-piece laser, and 7 is a guide for an optical fiber. The silica-based glass optical waveguide 2 has a seven-figure shape and has three end faces 2a, 2b, and 2C. A semiconductor laser 3 bonded onto the silicon substrate 1 is housed between the guides 6 and 6 on the end face 2a.
A light receiving element 4 bonded onto the silicon substrate 1 is connected to the end surface 2b, and an optical fiber 5 housed between the guides 7 and 7 is connected to the end surface 2C.

To operate the waveguide optical module with the above configuration, a driving current is applied to the semiconductor laser 3 (lead wires are omitted in the figure).
is applied to cause oscillation. The signal light from the '12 conductor laser 3 is transmitted to the silica-based glass optical waveguide 2 via the end face 2a, and is introduced into the optical fiber 5 via the end face 2C. vice versa,
The signal light from the optical fiber 5 passes through the end face 2C to the silica-based glass optical waveguide 2, and a part of it is detected by the light receiving element 4 via the figure 7-shaped branch and the end face 2b.

Note that although the semiconductor laser 3 generates heat, this heat is dissipated to the silicon substrate 1 having good thermal conductivity, so that continuous operation can be performed.

Next, the structure of each part will be explained in more detail.

FIG. 2 is an explanatory diagram of the manufacturing process of the silica-based glass optical waveguide 2. In order to form the optical waveguide 2, a silica-based glass optical η-wave film 21 is first formed on the silicon substrate 1. Unnecessary portions of the quartz-based glass optical four-wave film 21 are removed by a method such as reactive ion etching using a fluorine-based gas, leaving the optical waveguide 2. In order to form the quartz-based optical diaphragm film 21, the "method for manufacturing an optical diaphragm film" previously proposed by the applicant (
The method described in Japanese Patent Application No. 58-1473) can be used. That is, 5iCJ4. After depositing a glass fine particle film on the silicon substrate 1 using a flame hydrolysis reaction of a glass forming raw material gas such as TiCji, in an electric furnace,
It can be formed by heating a glass fine particle film to make it transparent vitrified. The leading wave film 21 usually includes a buffer layer 21a and a core layer 21b.

It consists of five stones of cladding F121C. Core diagram 21
The thickness of b is set to be approximately equal to the core diameter of the optical fiber 5 used together. The core diameter of the optical fiber 5 is approximately 50 μm for multimode and 5 to 10 μm for single mode. Note that it is convenient to form the guides 6.7 by leaving a part of the optical waveguide film 21 for a guide portion when forming the optical waveguide 2 shown in FIG. 2 by etching. At this time, the optical waveguide and guide patterns can be transferred m* well by photolithography using a single photomask as a base, so the alignment between the optical waveguide 2 and the guide 6.7 is automatic. will be achieved.

As a method of bonding the semiconductor laser 3 and the light receiving element 4 onto the silicon substrate 1, for example, Au-8n alloy is vapor-deposited on the surface of the substrate 1 at a desired portion, and the element cut out according to the shape of the guide 6.7 is guided. 6.7, and bonding to the silicon substrate 1 by thermocompression bonding or the like can be applied. In the embodiment shown in FIG.
A special guide is not provided for this purpose, but this is because the light receiving area of the light receiving element 4 is relatively large and alignment with the end surface 2b is relatively easy. A similar guide may also be provided.

The reason why the silica-based glass optical waveguide 2 is used in the present invention is that when silica glass is used, the optical waveguide 2 can be stably formed on the silicon substrate 1 with a thickness of several tens of μm.
This is because it is advantageous in terms of size and material for connection with commonly used silica-based optical fibers.

The etching depth h in FIG. 2 should be selected so that the core portion of the optical fiber 5 coincides with the core layer 21b of the optical waveguide 2 when the optical fiber 5 is inserted between the guides 7.7. For example, when connecting an optical fiber 5 with an outer diameter of 70 μm and a core diameter of 50 μm to an optical waveguide 2 in which the thicknesses of the buffing layer 21a, the fur D21b, and the cladding 1ff121c are 10 μm, 45 μm, and 10 μm, respectively, the etching depth h is 67μm±5μm
It is desirable to keep it at a certain level.

In this case, if the interval between the guides 7.7 is selected to be about 70 to 75 μm, optical axis alignment can be completed automatically by simply inserting the optical fiber 5 between the guides 7.7, which is efficient. For fixing the optical fiber 5, an adhesive or a @ bonding method using a CO2 laser can be applied.

In addition, when connecting an optical fiber 5 with an outer diameter of 125 μm, the etching depth h is increased to around 95 μm.
Further, the interval between the guides 7.7 may be widened to about 125 to 130 μm.

The thickness of the semiconductor laser 3 is such that when bonded onto the silicon substrate 1, the height of the transmission layer is equal to the core 1ff of the optical waveguide 2.
121b is located near the center.
Necessary for optical coupling. Therefore, it is desirable that the thickness of the semiconductor laser 3 be as thin as about 50 .mu.m. However, reducing the thickness of the semiconductor laser 3 to 30 μm or less is often difficult to handle, so the portion of the silicon substrate 1 to be bonded is selectively etched deeper by one-line etching or chemical etching. It is also effective to dig deeper.

FIG. 3 is a tree diagram of another embodiment in which a semiconductor laser 3 is mounted on a silicon substrate, in which a spacer 31 with good thermal conductivity is interposed between the silicon substrate 1 and the semiconductor laser 3, and The optical waveguide 2 is joined so that m3a is located on the lower side.
The height can be adjusted. in this case,
As the spacer 31, a flaky silicon plate or a diamond plate can be used. If the optical waveguide 2 is for a single mode, the spacer 31 may be omitted.

Note that in order to increase the coupling efficiency between the semiconductor laser 3 and the optical waveguide 2, the end face of the optical waveguide 2 may be processed into a circular or spherical shape.

The distance between the semiconductor laser guides 6.6 is half-width - If
3, the alignment with the optical waveguide 2 is automatically achieved, but the distance between the guides 6.6 is made to widen in a tapered shape as it moves away from the end surface 2a of the optical waveguide 2. This makes it easy to insert the semiconductor laser 3.

FIG. 4 is a diagram showing another embodiment of the present invention, and shows a waveguide optical module for wavelength multiplex communication. On the silicon substrate 1, a silica-based glass optical waveguide 2 and a guide 6.
7, 8.9 are formed, a semiconductor laser 3 is installed between the guides 6.6, an optical fiber 5 is inserted between the guides 7.7, and a light receiving element 4 is inserted between the guides 8, 8. It is accommodated.

An interference film type wavelength filter 41 is provided between the guides 9 and 9.
is inserted. The wavelength filter 41 has wavelength selectivity and has the characteristic of reflecting the wavelength λ of the light emitted by the semiconductor laser 3 and passing the wavelength λ2 of the light propagated through the optical fiber 5.

To operate this, the semiconductor laser 3 is driven to send signal light with a wavelength λ1 into the optical waveguide 2.

This signal light is reflected by the wavelength filter 41, and the optical waveguide 2
is introduced into the optical fiber 5 along the line. The signal light of wavelength λ2 propagated through the optical fiber 5 passes through the wavelength filter 41 and is guided to the light receiving element 4. Usage wavelength λ1. λ2
For example, (λ+-0.85 μm, λ2=1.
3 μm) , (λ1=0.81 μlll,
λ2=O,s9μm), (λ1=1.2μ
m, λ3 = 1.311 m), etc. are possible.

It goes without saying that the structure shown in FIG. 4 can be extended to a multi-wavelength platform/demultiplexer module equipped with a large number of lasers, light receiving elements, and wavelength filters.

(Effects of the Invention) Three embodiments have been described above. In the embodiment shown in FIG. I was able to fit it in. In addition, in the example shown in Figure 4, the reflection angle was set to 30'' and it was possible to fit it onto a 10 mm x i Qmm substrate.This is much smaller than conventional bulk type optical components. .Furthermore, the combined waveform module of the present invention has the following characteristics:
One four-mask! The same pattern can be repeatedly drawn on a 3-inch, 4-inch, or 5-inch diameter silicon wafer and then copied in bulk using photolithography.
It is suitable for giving birth. Furthermore, optical waveguides, optical fibers, receivers,
Since positioning with the light emitting element can be accomplished in a short time, it is possible to reduce the cost of optical components. Furthermore, heat generated from a semiconductor laser or the like is quickly absorbed by the silicon substrate, so stable operation can be achieved. Note that, if necessary, an electronic circuit for driving a semiconductor laser, an amplifier for a light-receiving element, and the like can be mounted in the empty space on the silicon substrate to achieve high-performance integration of optical components.

Furthermore, the I-structure shown in FIG. 1, FIG. 3, or FIG. 4 can ultimately be used by being housed in a package similar to that of an electrical integrated circuit; This greatly contributes to lower prices.

[Brief explanation of drawings]

FIG. 1 is a perspective view of an embodiment of the present invention, and FIG. 2 is an explanatory diagram of the manufacturing process of a silica-based glass optical waveguide.
A) is a sectional view taken along the line ■-■ in Figure 1 before etching, and Figure 2 (B) is a cross-sectional view taken along the line ■-■ in Figure 1 after etching.
■A sectional view taken along the line, FIG. 3 is a diagram showing another embodiment of the present invention with some parts omitted, and is an explanatory diagram showing an example of mounting dimensions of a semiconductor laser on a silicon substrate, and FIG. FIG. 3 is a perspective view showing still another embodiment of the present invention. DESCRIPTION OF SYMBOLS 1... Silicon substrate, 2... Silica-based glass optical waveguide, 2a, 2b, 2c... End face of optical waveguide, 3... Semiconductor laser (light emitting element),
3a... Transmission layer, 4... Light receiving element, 5
...Optical fiber, 6... Guide for semiconductor laser, 7... Guide for optical fiber, 8...
... Guide for light receiving element, 9 ... Guide for wavelength filter, 21 ... Quartz-based glass optical waveguide film,
21a...Buffer layer, 21b...Core layer, 21C...Clad layer, 3a...
・Outgoing layer, 31... Spacer, 41...
・Wavelength filter. Figure 1 Figure 3 Procedural Amendment J JIWA Showa Year Month Date Mr. Oka, Commissioner of the Patent Office. 1. Indication of the incident Patent Application No. 167677 of 1982 2. Name of the invention Waveguide optical module 3. Person making the amendment

Claims (1)

[Scope of Claims] (1.) A silica-based glass optical waveguide formed on a silicon substrate;
A waveguide optical module comprising a light emitting element and an optical fiber connected to another end face of the optical waveguide. (2.) The waveguide optical module according to claim 1, wherein the core layer thickness of the optical waveguide is formed to have approximately the same dimension as the core diameter of the optical fiber.