JPH04204403A - Optical multiplexing/demultiplexing module - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an optical multiplexing/demultiplexing module for optical wavelength multiplexing transmission.

[Prior art] A conventional optical multiplexing/demultiplexing module is disclosed in Japanese Patent Application Laid-Open No. 60-184216.
As described in the publication, a bulk type multiplexer/demultiplexer block was used in the optical multiplexer/demultiplexer.

FIG. 2 is a diagram illustrating this conventional wavelength multiplexing transmitting/receiving module. In FIG. 2, this wavelength multiplexing transmitter/receiver module includes an optical fiber 22 on a ceramic substrate 21, a light emitting element package 23, a light receiving element package 24, a common holder 25, and an interference film filter 2 on a glass block 26.
This is a structure in which an optical multiplexer/demultiplexer is mounted with 7 glued together.

With this configuration, the parallel beam of wavelength λ1 from the light emitting element package 23 passes through the interference film filter 27 of the optical multiplexer/demultiplexer and the glass block 26, and is focused onto the optical fiber 22 by the common holder 25. On the other hand, the wavelength λ from the optical fiber 22
The light of No. 2 is converted into a parallel beam by the common holder 25, passes through the glass block 26 of the optical multiplexer/demultiplexer, is reflected by the interference film filter 27, passes through the glass block 26, and is focused onto the light receiving element by the lens of the light receiving element package 24. be done.

This wavelength multiplexing transmitter/receiver module includes light emitting/receiving element packages 24, 23, a common holder 25, and a glass block 2.
6 and an optical multiplexer/demultiplexer to which an interference film filter 27 is bonded are integrated on a ceramic substrate 21.

[Problem to be Solved by the Invention] The above conventional technology performs optical multiplexing and demultiplexing using an interference film filter, so there is a large degree of freedom in designing the filter, so it is relatively easy to obtain multiplexing and demultiplexing characteristics with low harmonic attenuation over a wide band. Moreover, since the light emitting element package, the glass block, and the common holder are mounted on the ceramic substrate, there is an advantage that adjustment-free assembly of multimode optical fibers is possible.

However, in the above conventional technology, since the optical multiplexing/demultiplexing glass block takes the optical path as shown in Figure 2, there are certain restrictions on the size, making it difficult to downsize, and the processing accuracy of the glass block requires high precision. It is also difficult to reduce the price because of the high demand. Furthermore, when a single mode fiber is used for the transmission line, it is impossible to assemble the above-mentioned module without adjustment, so highly accurate optical axis adjustment is required during assembly. In other words, assuming that the optical axis direction is the Z axis, it is necessary to simultaneously adjust the five axes: X, Y, the two axes perpendicular to the Z axis, the tilt θ of the xZ plane, the tilt ρ of the YZ plane, and the distance Z between the common holder lens and the optical fiber. Therefore, the assembly process is complicated and requires many man-hours, making mass production and price reduction difficult. In addition, the optical system of this module must be constructed with a confocal lens system, and three lenses are required even for two-wave multiplexing, reducing the number of parts.
It is difficult to lower the price. Furthermore, when the case is hermetically sealed and fixed to prevent condensation, a large force is applied to the ceramic substrate, causing optical axis deviation and increased loss.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems of the prior art and provide a small and inexpensive wavelength division multiplexing transmitting/receiving module.

Means for Solving the U Problems] In order to achieve the above object, the optical multiplexing/demultiplexing module of the present invention has an optical multiplexing/demultiplexing section that replaces the conventional bulk type, allowing easy mass production and miniaturization and low cost. An optical waveguide layer containing a directional coupler is formed on a substrate that can be etched with high precision, and a rectangular hole is formed in the waveguide layer so that a light emitting element and a light receiving element can be mounted. By forming a V-groove so that an optical fiber can be mounted from the other side, the optical waveguide layer, the light emitting/receiving element, and the optical fiber can be optically coupled without using a lens. Reduced number of parts,
By aiming at miniaturization and lowering the price, and furthermore, by monolithically forming an electric circuit on the back side of the optical waveguide layer on the Si substrate, further miniaturization and lowering the price are made possible.

[Function] In the optical multiplexing/demultiplexing module described above, the optical waveguide layer on the 81 board, which has a directional coupler as a component, has a multiplexing/demultiplexing function, and by applying the above processing to the end face of this waveguide layer, , a light emitting/receiving element, and an optical fiber are arranged, and furthermore, a transmitting circuit and a receiving circuit are monolithically formed on the back side of the optical waveguide layer, thereby functioning as an integrated optical multiplexing/demultiplexing module.

〔Example〕

Embodiments of the present invention will be described below with reference to FIG.

FIG. 1(a) is a front view of the optical multiplexing/demultiplexing module.

(b) is a side view on the light emitting element side, (c) is a side view on the light receiving element side, and (d) is a side view on the optical fiber side. The optical multiplexing/demultiplexing module of the present invention has a cladding 1b-1, a core 1b-2, a buffer layer 1b, as shown in FIGS.
-3Si substrate 1b-4, electric circuit layer 1b-5, light emitting element 1b-6, light emitting element, system 1b-7 light receiving tag 1cm
It is composed of 6 light-receiving element systems, 1 cm long, 7 optical fibers 1b-8, and an optical fiber guide 1b-9. The optical waveguide layer is 8
A puffer layer (refractive index nb) is provided on one substrate, and a rectangular core (refractive index n,) on which light is guided.

It has a so-called buried waveguide structure in which the entire core is covered with a cladding (tangent index n., nc>n,). In addition, the tapered optical fiber is placed on a waveguide substrate 1d-1 processed into a V-groove shape as shown in Figure 1(d).
The light guide 1d- is pressed into the hole and similarly processed into a V-groove shape.
It is fixed by 2. The light emitting element is attached to the stem, and is further dropped into a rectangular hole provided on the waveguide and fixed by the stem. The light receiving element is also attached to the stem in the same way, and is further dropped into a rectangular hole provided on the waveguide and fixed by the stem portion. Further, a transmitting circuit and a receiving circuit are monolithically formed on the substrate on the opposite side of the optical waveguide layer, and the elements and the transmitting circuit electrode button and the receiving circuit electrode button are connected by wire bonding or the like.

With the above configuration, the light of wavelength λ from the optical fiber is shown in Figure 1 (
As shown in a), the light is demultiplexed from the common waveguide 1a-1 by the directional coupling portion 1a-2, propagates through the demultiplexing waveguide 1a-3, and reaches the light receiving element 1a-4. On the other hand, light emitting element 1a-
The light emitted from 5 is directly coupled to the core of the waveguide layer, propagated through the multiplexing waveguide 1a-6, and coupled from the common waveguide 1a-1 to the optical fiber. Furthermore, the light emitting element could be driven by a transmitting circuit formed on the back surface. The photocurrent from the light receiving element is converted into a signal by the receiving circuit on the back side.

Therefore, this module has wavelength λ1. λ, functions as a bidirectional optical multiplexing/demultiplexing module.

Next, a method for manufacturing this module will be explained.

In this module, first, an optical waveguide layer consisting of a buffer layer, a core, and a cladding is formed on a Si substrate, and a monolithic electric circuit is formed on the back side of the optical waveguide layer. The former can be formed using a normal glass waveguide forming technique, and the latter can be formed using a semiconductor 0EIC manufacturing technique. Next, on the optical waveguide layer side thus formed, a V-groove for fixing the optical fiber and a rectangular hole for fixing the light emitting/receiving element are formed by making full use of high precision processing techniques such as dry etching. Furthermore, the tapered optical fiber is
'a, and fix it with the light guide that has already been processed with V4I. At this time, if the machining accuracy of the V-groove is made sufficiently high, the optical fiber can be fixed without any adjustment. Next, the light emitting element and light receiving element already fixed to the stem can be combined by fine adjustment of the X and Y axes. Finally, the light emitting element and the electrode tabs of the transmitting circuit, and the light receiving element and the electrode tabs of the receiving circuit are connected by means such as wire bonding.

〔Effect of the invention〕

According to the present invention, an optical waveguide layer having an optical multiplexing and demultiplexing function is formed on the $1 substrate, and the directional coupler is a component, and the transmitter circuit and the receiver circuit are monolithically installed on the back side of the optical waveguide layer to improve productivity. A V-groove for fixing the optical fiber is formed on the waveguide substrate formed by high patch processing, the tapered optical fiber is fixed without adjustment, and the light emitting/receiving element is fixed in the rectangular hole for fixing the light emitting/receiving element. This has the potential to reduce the number of parts such as lenses and simplify optical axis adjustment, making it possible to mass-produce small, low-cost modules.

[Brief explanation of the drawing]

FIG. 1(a) is a front view showing one embodiment of the present invention.
b), (c), and (d) are side views thereof, and FIG. 2 is a diagram illustrating a conventional optical multiplexing/demultiplexing module. Explanation of symbols Ia-1, 1b-8, 2b-8, 1d-3・Optical fiber, 1a-2 directional coupler, 1a-3° branching waveguide, Ia
-4.2cm6 light receiving element. Ia-5, 1b-6 light emitting element, 1a-6 multiplexing waveguide,
1b-1,2cm1 - cladding. 1b-2,2cm2-core, 1b-3,2cm3
Buffer layer, 1b-4, 1d-1, 2cm4--S
i board, 1b-5, 2cm5 electric circuit layer,
1b-7, 2cm7 stem, 1b-9, 1d ~ 2, 2c
m9 --- Guide VJ l Mouth ? Mouth 7:5 2'7

Claims (1)

[Claims] 1. A waveguide layer having an optical multiplexing and demultiplexing function whose constituent elements are directional coupling parts consisting of curved and straight optical waveguides is provided on one surface of a Si single crystal substrate, and this waveguide layer A multiplexing waveguide through which the combined light is transmitted, a demultiplexing waveguide through which the demultiplexed light is transmitted, and a common waveguide through which both the demultiplexed light and the combined light are transmitted, A rectangular hole is provided on the extension of the branching waveguide and the combining waveguide, and a light emitting element and a light receiving element are mounted in this part.
An optical multiplexing/demultiplexing module 2 characterized in that a groove is formed, an optical fiber processed into a tapered shape is mounted in this V-groove, and the optical fiber is further fixed by another guide in which a V-groove is formed in advance. 2. An optical multiplexing/demultiplexing module characterized in that a transmitting circuit and a receiving circuit are monolithically formed on the surface on which the optical waveguide layer is formed or the opposite surface of the substrate of the optical multiplexing/demultiplexing module according to item 1.