JPH05333248A - Wavelength division multiplex system transmit-receive module and optical transmitter using same - Google Patents

Abstract

PURPOSE:To easily load a waveguide type wavelength division/multiplex system transmit-receive module by improving the allowable quantity of axial deviation loss in an LD transmitting part and a waveguide multiplying/demultiplying part, and to improve a module characteristic by drastically reducing the return light to the LD. CONSTITUTION:A 1st lens 6 for making the optical transmitted from semiconductor laser 4 parallel rays of light and a 2nd lens 7 for condensing the light emitted from the 1st lens 6 are concentrically arranged between the semiconductor laser 4 and a waveguide substrate 8, and one end surface 7a of the 2nd lens 7 on the side of the waveguide substrate 8 and the end surface 8a of the waveguide substrate opposite to the end surface 7a are inclined by an acute angle, and these inclined surfaces are overlapped parallel to each other, and a directional coupler 11 is formed on the waveguide substrate 8, and an optical waveguide part 12 for connecting the 1st port of the coupler with a transmission optical fiber 17 and also for connecting the 2nd port with the inclined surface 8a of the waveguide substrate 8 and the optical waveguide part 14 for connecting the 3rd port with a light receiving element 9 are formed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a semiconductor laser (hereinafter,
The present invention relates to a wavelength division multiplexing transmission / reception module equipped with a light emitting element and a light receiving element such as an LD) and an optical transmission device using the same.

[0002]

2. Description of the Related Art A wavelength division multiplexing transmission / reception module using a conventional optical waveguide (hereinafter referred to as WDM module)
Is shown in FIG. As shown in this figure, the WDM module includes an LD transmitter 21, a waveguide-type multiplexer / demultiplexer 22 using a silica-based optical waveguide, which has low loss and good matching with an optical fiber, and a PD receiver. The sub-module, which is composed of the transmission fiber section 23 and is a constituent section, is fixed by welding with a YAG laser after adjusting the optical axis.

The waveguide type multiplexer / demultiplexer 22 is composed of a directional coupler type multiplexer / demultiplexer circuit, and the transmission light from the LD 24 passes from the port of the waveguide type multiplexer / demultiplexer 22 to the port, and P
It is sent to the transmission optical fiber 28 side of the D reception / transmission fiber unit 23. On the contrary, the received light from the transmission optical fiber 28 is
The light enters from the port of the waveguide type multiplexer / demultiplexer 22, moves to the port side of the waveguide 26 by the directional coupler 25, and is received by the PD (photodiode) 27 which is a light receiving element provided in the PD receiving / transmitting fiber 23. To be done.

The waveguide type multiplexer / demultiplexer 22 has a wavelength on the LD transmitting side of 1.55 μm and a wavelength on the PD receiving side of 1.3.
Since it is designed to have the wavelength-multiplexing / demultiplexing characteristics as shown in FIG. 4 at μm, LD transmission light with a wavelength of 1.55 μm goes from port to port, and received light with a wavelength of 1.3 μm goes from port to port. Move.

[0005]

However, the prior art W
The DM module has the following drawbacks.

(1) LD transmitter 21, waveguide type multiplexer / demultiplexer 2
2 and 3 sub-modules of the PD receiving / transmitting fiber unit 23, so-called three packages, are required.
Not only is the size and shape increased, but the structure is complicated.

(2) When the LD 24 and PD 27 are bare elements, that is, elements that are not hermetically sealed, each of the three packages must be hermetically sealed.

(3) LD transmitter 21 and waveguide type multiplexer / demultiplexer 2
Since the axis deviation amount of 2 is as severe as about 4 μm when the connection loss increases by 1 dB, mounting is difficult.

(4) The power of the LD 24 is unstable due to the influence of the return light of the transmitted light from the LD transmitter 21, which affects the characteristics of the WDM module.

An object of the present invention is to provide a waveguide type wavelength division multiplexing transmission / reception module which can solve the above-mentioned drawbacks of the prior art, facilitate mounting, and improve module characteristics.

[0011]

A wavelength division multiplexing transmission / reception module of the present invention comprises a light emitting element for generating an optical signal of a predetermined wavelength and a light receiving element for receiving an optical signal transmitted from a counterpart transmission / reception module. And an optical fiber for propagating the transmitted / received optical signal, and a waveguide substrate arranged between the light emitting element and the optical fiber, the waveguide substrate transmitting the optical signal from the light emitting element to the optical fiber. A first waveguide that leads to a first waveguide, and is formed in parallel with the first waveguide so as to form a directional optical coupler with the first waveguide on the optical fiber side, and the light emitting element side of the waveguide substrate. A second waveguide extending to the end face, and a light guide element for guiding an optical signal reflected by the end face of the second waveguide on the light emitting device side to the light receiving device provided on the end face of the waveguide substrate opposite to the light emitting device. Composed of 3 waveguides To have.

Further, in the optical transmission device of the present invention using the above module, the first transmission / reception module and the second transmission / reception module are connected through one optical fiber, and the first and second transmission / reception modules are connected. In the wavelength division multiplexing optical transmission device, wherein the modules transmit the first and second optical signals having different wavelengths and receive the optical signal transmitted from the other party, the first and second transmission / reception modules Each of which is a light emitting element that generates an optical signal of a predetermined wavelength, a light receiving element that receives an optical signal transmitted from a transmission / reception module of the other party, and a waveguide that is arranged between the light emitting element and the optical fiber. A substrate, the waveguide substrate guiding the optical signal from the light emitting element to the optical fiber;
And a waveguide formed in parallel with the first waveguide so as to form a directional optical coupler with the first waveguide on the optical fiber side and extending to the end face of the waveguide substrate on the light emitting element side. A second waveguide that exists and a third guide that guides the optical signal reflected by the end face of the second waveguide on the light emitting device side to the light receiving device provided on the end face of the waveguide substrate on the opposite side of the light emitting device. And a waveguide.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to illustrated embodiments.

In FIG. 1, in a box-shaped package 1, a first pedestal 2 and a second pedestal 3 are arranged so as to face each other in a straight line. The first pedestal 2 is formed in an L-shaped cross section, and the LD 4 is disposed on the fixed base portion thereof, and the V groove 5 is provided on the end side of the LD 4 facing the second pedestal 3. A cylindrical first lens 6 positioned by is provided. On the other hand, on the second pedestal 3, a cylindrical second lens 7 positioned by the V groove is provided on the end side facing the pedestal 2, and the second lens 7 is further provided.
Then, the waveguide substrate 8 and the PD 9 are sequentially provided. The LD monitor PD 10 is fixed to the L-shaped standing portion of the first pedestal 2.

The first lens 6 and the second lens 7 are made of quartz or plastic, and the one end surface on the LD4 side is spherically processed to make the first lens 6 parallel light emitted from the LD4. On the other hand, the second lens 7 is coaxially arranged with a certain distance from the first lens 6 so as to receive the parallel light, and one end surface of the second lens 7 on the waveguide substrate 8 side has a predetermined angle, here, 7 Diagonally cut or polished at -9 degrees. The waveguide substrate 8 is also made of quartz or plastic, and is arranged concentrically with the first lens 6 and the second lens 7, and the end face facing the second lens 7 is substantially the same as the slope 7a of the second lens 7. It is obliquely cut or obliquely polished at an angle, and the sloped surface 8a of the end face of the waveguide substrate 8 is placed parallel to the sloped surface 7a of the second lens 7 so as to vertically overlap.

After all, the first lens 6, the second lens 7 and the waveguide substrate 8 correspond to three elements when one optical system for optically coupling the LD 4 and the PD 9 is divided into three parts. The spatial light transmission section is formed between the lenses.

The waveguide substrate 8 has a directional coupler 11 formed in the vicinity of the end on the side where the second lens 7 does not exist, and a second port of the directional coupler 11 (corresponding to the port of FIG. 3). An optical waveguide portion 12 which is connected to
The optical waveguide unit 13 extends from the third port (corresponding to the port in FIG. 3) to the slope 8a, and the optical waveguide unit 14 is continuous with the optical waveguide unit 13 with the slope 8a as an anti-slope and continues from the slope 8a to PD9. Directional coupler 1 of this waveguide substrate 8
A transmission optical fiber 17 is connected to the first port 1 (corresponding to the port of FIG. 3).

Reference numeral 15 denotes L mounted on the first pedestal 2.
D4 is a wire for electrical connection to the PD 10 for LD motor or PD 9 mounted on the second pedestal 3, and is connected to the electrode pin 16 penetrating the bottom surface of the package 1.
After mounting each component, the package 1 is placed in a nitrogen atmosphere, and a lid (not shown) is fixed to the opening of the package 1 by soldering, welding, or the like, and then sealed.

First, the transmitted light emitted from the LD 4 is made into substantially parallel light by the first lens 6 having one end spherically processed, and is condensed by the second lens 16, and the sloped surface 7a of the end surface on the waveguide substrate 8 side. The light is further emitted and enters the waveguide substrate 8 through the inclined surface 8a parallel thereto. Then, it enters the transmission optical fiber 17 from the optical waveguide section 12 through the directional coupler 11,
Is transmitted. On the other hand, when the light incident from the transmission optical fiber 17 side is incident on the waveguide substrate 8, the light is moved to the PD-side waveguide portion 13 by the directional coupler 11, and the optical waveguide portion after reflection on the slope 8a is formed. The light is received by the PD 7 through 14.

In this case, the end surface of the first lens 6 on the LD side is spherically processed, and the end surface of the second lens 7 on the waveguide substrate side and the end surface of the waveguide substrate in contact therewith are obliquely cut at an acute angle of 7 to 9 degrees. Therefore, the return light to the LD 4 generated in the optical system including the first lens 6, the second lens 7 and the waveguide substrate 8 is very small. Further, since the transmission light of the LD 4 is condensed on the waveguide substrate 8 by using the spatial light transmission section composed of the two lenses 6 and 7, the allowable amount of axial deviation between the LD transmission section and the waveguide multiplexing / demultiplexing section is reduced. Increased and easier to implement.

As shown in FIG. 2, the optical fiber hermetically sealing portion 18 encloses the low melting point glass 18a in the hollow cylindrical portion 1b which projects the package 1 outwardly. The end surface of the hollow cylindrical portion 1b is obliquely cut so that the low melting point glass 18a can be easily enclosed. A half sleeve 18b is covered on the outer circumference of the hollow cylindrical portion 1b, and a plastic 18d such as an ultraviolet curable epoxy resin is provided on the inside thereof.
Is filled. The outer circumference of the half sleeve 18b is covered with a rubber boot 18d for protection.

In the embodiment shown in FIG. 1, the transmission light oscillated by the LD 4 and guided to the optical waveguide section 12 causes a coupling loss at the end face connected to the transmission optical fiber 17, and this loss becomes stray light. Detected by the photodiode 9,
Similarly, the received light transmitted through the transmission optical fiber 17 may also generate stray light at the end face of the waveguide 8, and the isolation between the transmission and reception may deteriorate. Such deterioration of isolation due to stray light is, for example, as shown in FIG.
The light blocking block 19 is arranged in the space between the LD 4 and the PD 9, or the end surface 20 of the waveguide substrate 8 on the side of the directional coupler 11 is projected more than the end surface on the side of the PD 9 as shown in FIG. This can be prevented.

FIG. 4 is an explanatory view showing an optical transmission device for performing wavelength division multiplexing transmission using the above module.

The first module 22a has a wavelength of 1.31 μm
LD4a that oscillates the light of the first lens 6
a, the second lens 7a, the optical waveguide portion 12 of the waveguide substrate 8a
It is incident on the SM (single mode) transmission optical fiber 17 via a and the directional optical coupler 11a, and is transmitted to the second module 22b. Then, the light having a wavelength of 1.31 μm incident on the waveguide substrate 8b is guided to the optical waveguide portion 13b side by the directional optical coupling portion 11b of the waveguide substrate 8b, and reaches the one end surface of the waveguide substrate 8b. The light is reflected by the portion 14b and is incident on the PD 9b. Also, the second module 2
2b includes an LD 4b that oscillates light having a wavelength of 1.55 μm, and the light is emitted from the first lens 6b, the second lens 7b, the optical waveguide portion 12b of the waveguide substrate 8b, and the directional light coupling portion 11b.
It is incident on the transmission optical fiber 17 via the and is transmitted to the first module 22a. Then, the light having a wavelength of 1.55 μm incident on the waveguide substrate 8a is guided to the optical waveguide portion 13a side by the directional optical coupling portion 11a of the waveguide substrate 8a, and reaches the one end surface of the waveguide substrate 8a. Part 14a
And is incident on the PD 9a.

By constructing the optical transmission device in this way, wavelength division multiplexing transmission superior to the conventional one can be realized.

[0026]

As described above, according to the present invention, the module can be easily mounted, the module characteristics are improved, and the wavelength division multiplex transmission superior to the conventional one can be achieved. Play.

[Brief description of drawings]

FIG. 1 is a perspective view showing an embodiment of a WDM module of the present invention.

FIG. 2 is a perspective view showing another embodiment of the WDM module of the present invention.

FIG. 3 is a plan view showing an example of a waveguide substrate mounted on the WDM module of the present invention.

FIG. 4 is an explanatory diagram showing an embodiment of a wavelength division multiplexing transmission device of the present invention.

FIG. 5 is a perspective view showing an example of a conventional waveguide type wavelength division multiplexing transmission / reception module.

FIG. 6 is a diagram showing a multiplexing / demultiplexing characteristic of the waveguide type multiplexing / demultiplexing unit of FIG. 3;

[Explanation of symbols]

 1 Package 2 First Pedestal 3 Second Pedestal 4 LD (Semiconductor Laser) 5 V Groove 6 First Lens 7 Second Lens 7a Slope 8 Waveguide Substrate 8a Slope 9 PD (PD) 10 LD Monitor PD 11 Direction Sex coupler 12 optical waveguide part 13, 14 optical waveguide part 15 wire for electrical connection 16 electrode pin 17 transmission optical fiber 18 optical fiber hermetically sealed part

Front Page Continuation (72) Inventor Naoto Uezuka 5-1-1, Hidakacho, Hitachi City, Ibaraki Hitachi Cable Company, Ltd., Optro System Laboratories (72) Inventor Hiroyuki Kakuyama 5 Hidakacho, Hitachi City, Ibaraki Prefecture 1-1-1 Hitachi Cable Co., Ltd.

Claims (8)

[Claims] 1. A light emitting element for generating an optical signal of a predetermined wavelength, a light receiving element for receiving an optical signal transmitted from a partner transceiver module, an optical fiber for propagating the transmitted and received optical signal, and the light emission. A waveguide substrate disposed between the element and the optical fiber, the waveguide substrate including a first waveguide for guiding an optical signal from the light emitting element to the optical fiber, and the waveguide on the optical fiber side. A second waveguide that is formed in parallel with the first waveguide so as to form a directional optical coupler with the first waveguide and extends to an end face of the waveguide substrate on the light emitting element side; And a third waveguide for guiding an optical signal reflected by the end face of the waveguide of the second waveguide on the light emitting device side to the light receiving device provided on the end face of the waveguide substrate on the opposite side of the light emitting device. Send / receive module. 2. The light emitting element, the light receiving element, and the waveguide substrate are housed in one housing, and an optical fiber introducing portion of the housing for introducing the optical fiber is hermetically sealed. The transmission / reception module according to claim 4. 3. The optical fiber introducing portion, a hollow cylindrical portion projecting outwardly of the casing, a low melting point glass filled in the hollow cylindrical portion, a sleeve covering the hollow cylindrical portion, The transceiver module according to claim 5, wherein the transceiver module is made of plastic filled in the sleeve. 4. The end face of the waveguide substrate optically connected to the optical fiber is convexly projected to the optical fiber side from the end face of the waveguide substrate on which the light receiving element is arranged. Item 4. The transceiver module according to item 4. 5. A transmission / reception module in which a light shield is provided in a space between the light emitting element and the light receiving element in the housing. 6. A first transmission / reception module and a second transmission / reception module are connected via a single optical fiber, and the first and second transmission / reception modules respectively have different wavelengths of first and second light. In the wavelength division multiplexing optical transmission device configured to transmit a signal and receive an optical signal transmitted from the other party, each of the first and second transmission / reception modules generates an optical signal having a predetermined wavelength. A light emitting element, a light receiving element for receiving an optical signal transmitted from a counterpart transmission / reception module, and a waveguide substrate arranged between the light emitting element and the optical fiber, and the waveguide substrate is the light emitting element. First guiding an optical signal from an element to the optical fiber
And a waveguide formed in parallel with the first waveguide so as to form a directional optical coupler with the first waveguide on the optical fiber side and extending to the end face of the waveguide substrate on the light emitting element side. A second waveguide that exists and a third guide that guides the optical signal reflected by the end face of the second waveguide on the light emitting device side to the light receiving device provided on the end face of the waveguide substrate on the opposite side of the light emitting device. A wavelength division multiplexing optical transmission device comprising: a waveguide. 7. The first transmission / reception module (or the second transmission / reception module) transmits an optical signal having a wavelength of 1.3 μm band, and the second transmission / reception module (or the first transmission / reception module) 1. The wavelength division multiplexing optical transmission device according to claim 1, which transmits an optical signal having a wavelength of 5 μm band. 8. One end of the optical fiber is connected to a first waveguide of the waveguide substrate in the first transceiver module, and a second waveguide of the waveguide substrate in the second transceiver module is connected. 3. The wavelength division multiplexing optical transmission device according to claim 1, wherein the other end of the optical fiber is connected to the waveguide.