JPH10341027A - Optical module - Google Patents

Abstract

(57) [Problem] To provide an optical module having high performance even in a high frequency range. An optical module comprising at least an optical element and a microstrip line is provided.
The optical element 103 is arranged laterally on the side surface of the substrate of the microstrip line 104, and one electrode 103a of the optical element is used as the signal electrode 104a of the microstrip line 104, and the other electrode 103b is used as the microstrip line. 104 is connected to the ground electrode 104b.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention generally relates to an optical module in which a semiconductor optical device is mounted on a microstrip line, and more specifically, a semiconductor optical device is mounted on a side surface of a microstrip substrate to reduce parasitic capacitance. And an optical module having a feature in a structure for simplifying mounting.

[0002]

2. Description of the Related Art In a conventional general optical module, taking a waveguide type light receiving element as an example, as shown in FIG. 5, an optical fiber 501, an optical lens 502, and a waveguide type light receiving element 5 are used.
03, microstrip line 504, coaxial connector 5
05 and a package 506 for fixing them. In this optical module, an optical signal introduced from an optical fiber 501 is condensed by an optical lens 502 and is incident on a waveguide type light receiving element 503.

[0003] Between the waveguide type light receiving elements 503, an incident optical signal is converted into an electric signal, and the electric signal is taken out of the module from the coaxial connector 505 through the microstrip line 504. The microstrip line 504 is made of alumina or a semiconductor, and has a signal electrode 504a formed on the front surface of the substrate and a ground electrode 504b formed on the back surface of the substrate. The waveguide light receiving element 503 is made of a semiconductor, and has one signal electrode 503a formed on the surface and one ground electrode 503b formed on the surface.

The waveguide type light receiving element 503 is vertically connected to the side surface of the substrate of the microstrip line 504. The general electrical connection between the waveguide type light receiving element 503 and the microstrip line 504 is as follows. Depends on the method. That is, for the signal electrode, the two signal electrodes 503a and 504a disposed on the surface are connected by a metal wire or the like, and for the ground electrode, a through hole 504c is formed in a part of the microstrip line 504, and the through hole is formed. The ground electrode 504b of the waveguide type light receiving element 503 is drawn out with a metal wire, etc.
It is to connect with.

In another conventional optical module, taking a waveguide type light receiving element as an example, as shown in FIG. 6, an optical fiber 601, an optical lens 602, and a waveguide type light receiving element
03, a coplanar line 604, a coaxial connector 605, and a package 606 for fixing these components. In this optical module, an optical signal introduced from an optical fiber 601 is condensed by an optical lens 602 and is incident on a waveguide type light receiving element 603.

[0006] In the waveguide type light receiving element 603, an incident optical signal is converted into an electric signal, and the electric signal is extracted from the coaxial connector 605 to the outside of the module through the coplanar line 604. The coplanar line 604 is made of alumina or a semiconductor, and has a signal electrode 604a formed on the substrate surface and two ground electrodes 604b formed on the substrate surface. Waveguide type light receiving element 6
Numeral 03 is made of a semiconductor and has one signal electrode 603a formed on the surface and two ground electrodes 603b formed on the surface.

[0007] The coplanar line 604 is vertically connected to the side of the substrate of the waveguide type light receiving element 603, and the general electrical connection between the waveguide type light receiving element 603 and the coplanar line 604 is as follows. by. That is, with respect to the signal electrodes, the two signal electrodes 603a and 604a arranged on the surface are connected by a metal wire or the like, and the ground electrode is also connected to the two signal electrodes 603b and 604b arranged on the surface. Are connected by a metal wire or the like.

[0008]

In order to realize a high-performance module, it is necessary to minimize the loss of an electric signal in the module. In order to reduce the loss of the electric signal in the module, the connection between the optical element and the line must be connected so that the characteristic impedance of the line does not greatly change.

However, in the conventional connection form shown in FIG. 5, a through hole 504c is formed in a part of the microstrip line 504 at the connection portion, and the ground electrode 504b is drawn out to the surface. In this case, the characteristic impedance of the line greatly changes. In another conventional connection configuration shown in FIG. 6, the width and the interval of the metal wire at the connection portion are different from those of the coplanar line 60.
The characteristic impedance greatly changes due to a slight deviation from the width and interval of the electrode No. 4.

Therefore, in the conventional optical module, impedance mismatch occurs at the connection between the optical element and the line, and the loss of electric signals becomes remarkable especially in a high frequency region of 20 GHz or more, and a high-performance optical module is obtained. There was a problem that it could not be manufactured. SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems of the conventional technology and to provide an optical module having high performance even in a high frequency range.

[0011]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention is most characterized by arranging an optical element laterally on a side surface of a microstrip line substrate. The difference from the conventional technique is that the change in the impedance of the line at the connection with the optical element is extremely small.

[Operation] By arranging the optical element laterally on the side surface of the substrate of the microstrip line, the signal electrode and the ground electrode of the optical element can be pulled out to the signal electrode side and the ground electrode side of the microstrip line, respectively. Without processing the microstrip line, that is,
The optical element and the line can be connected without changing the impedance of the microstrip line, and as a result, a high-performance optical module with little loss of electric signal even in a high-frequency region can be realized.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION

Embodiment 1 FIG. 1 shows an optical module according to a first embodiment of the present invention. In the figure, 101 is an optical fiber, 102 is an optical lens, 103 is a waveguide light receiving element, 103a is a signal electrode of the waveguide light receiving element, 103b is a ground electrode of the waveguide light receiving element, 104 is a microstrip line, 104
a is a signal electrode of a microstrip line, 104b is a ground electrode of a microstrip line, 105 is a coaxial connector, and 106 is a package for fixing these.

In this optical module, an optical signal introduced from an optical fiber 101 is condensed by an optical lens 102 and is incident on a waveguide type light receiving element 103. In the waveguide type light receiving element 103, the incident optical signal is converted into an electric signal, and this electric signal is converted into a microstrip line 104.
Through the coaxial connector 105 to the outside of the module.

In the optical module of the present embodiment, the waveguide type light receiving element 103 is arranged laterally on the side of the substrate on the left front side of the microstrip line 104 in the drawing. In other words, the signal electrode 103a and the ground electrode 103b respectively formed on the surface of the waveguide type light receiving element 103 are parallel to the substrate side surface of the microstrip line 104, and the signal electrode 103a is It faces toward the signal electrode 104a, and the ground electrode 1
03b is the signal electrode 10 of the microstrip line 104
It is arranged so as to face the 4b side.

A conductive paste is connected between the signal electrode 103a and the signal electrode 104a, and between the ground electrode 103b and the signal electrode 104b. The waveguide type light receiving element 103 and the microstrip line 104 shown in this embodiment are connected to each other. In the connection mode (1), it is possible to connect to the waveguide type light receiving element without changing the shape of the microstrip line 104 even near the connection portion. As a result, the loss of the electric signal due to the impedance mismatch at 100 GHz is reduced from 5 dB of the related art to 1 d.
B was able to be reduced.

Embodiment 2 FIG. 2 shows an optical module according to a second embodiment of the present invention. In the figure, 201 is an optical fiber, 202 is an optical lens, 203 is a waveguide type light receiving element,
203a is a signal electrode of the waveguide type light receiving element, 203b is a ground electrode of the waveguide type light receiving element, 204 is a microstrip line, 204a is a signal electrode of a microstrip line, 204b is a ground electrode of a microstrip line, 2
05 is a coaxial connector, and 206 is a package for fixing them.

In this optical module, the optical fiber 2
The optical signal introduced from 01 is condensed by the optical lens 202 and enters the waveguide type light receiving element 203. The incident optical signal is converted into an electric signal in the waveguide light receiving element 203, and the electric signal is taken out of the module from the coaxial connector 205 through the microstrip line 204.

In the optical module of this embodiment, the waveguide type light receiving element 103 is arranged laterally on the side of the substrate on the right side of the microstrip line 204 in the drawing. In other words, the signal electrode 203a and the ground electrode 203b respectively formed on the surface of the waveguide type light receiving element 203 are parallel to the substrate side surface of the microstrip line 204.
In addition, the signal electrode 203a is connected to the microstrip line 20
4 to the signal electrode 204a side and the ground electrode 203
b is the signal electrode 204b of the microstrip line 204
It is arranged to face the side.

A conductive paste is connected between the signal electrode 203a and the signal electrode 204a and between the ground electrode 203b and the signal electrode 204b. Further, in this embodiment, the signal electrode 204a of the microstrip line 204 is coaxially connected. In a region connected to the connector 205, it is folded in parallel with the coaxial connector 205, and in a region connected to the waveguide type light receiving element 203, it is bent halfway so as to be inclined with respect to the coaxial connector 205.

As a result, the end of the signal electrode 204a connected to the waveguide type light receiving element 203 is connected to the coaxial connector 205.
Of the microstrip line 204 parallel to the right side of FIG. Waveguide-type light receiving element 2 shown in this embodiment
03 and the microstrip line 204, the microstrip line 20 is also provided near the connection.
The waveguide type light receiving element 203 can be connected without changing the shape of 4.

Further, the connection form between the waveguide type light receiving element 203 and the microstrip line 204 shown in this embodiment has a feature that the optical fiber 201 can be arranged in parallel with the coaxial connector 205. Also in the optical module shown in this embodiment, the loss of the electric signal due to the impedance mismatch at 100 GHz is reduced by 5 dB according to the related art.
From 1 to 1 dB.

Embodiment 3 FIG. 3 shows an optical module according to a third embodiment of the present invention. In the figure, 301 is an optical fiber, 302 is an optical lens, 303 is a surface incident type light receiving element,
Reference numeral 303a denotes a signal electrode of the surface incident type light receiving element, 303b denotes a ground electrode of the surface incident type light receiving element, 304 denotes a microstrip line, 304a denotes a signal electrode of the microstrip line, and 304b denotes a ground electrode of the microstrip line.
05 is a coaxial connector, and 306 is a package for fixing them.

In this optical module, the optical fiber 3
The optical signal introduced from 01 is condensed by the optical lens 302 and is incident on the surface incident type light receiving element 303. The incident optical signal is converted into an electric signal in the surface incident type light receiving element 303, and the electric signal is taken out of the module from the coaxial connector 305 through the microstrip line 304.

In the optical module of the present embodiment, the surface incident type light receiving element 303 is arranged laterally on the side of the substrate on the left front side of the microstrip line 304 in the figure. In other words, the signal electrode 303a and the ground electrode 303b respectively formed on the surface of the surface incident type light receiving element 303 are parallel to the side surface of the substrate of the microstrip line 304, and the signal electrode 303a is It faces toward the signal electrode 304a, and the ground electrode 3
03b is the signal electrode 30 of the microstrip line 304
It is arranged so as to face the 4b side.

The conductive paste is connected between the signal electrode 303a and the signal electrode 304a and between the ground electrode 303b and the signal electrode 304b. In the connection mode between the surface illuminated light receiving element 303 and the microstrip line 304 shown in the present embodiment, the surface illuminated light receiving element 3 can be used without changing the shape of the microstrip line 304 even near the connection portion.
03 can be connected.

As a result, the loss of the electric signal due to the impedance mismatch at 20 GHz is reduced by 3
It was able to be reduced from dB to 0.5 dB. It is also possible to combine the microstrip line 204 bent in the middle shown in the second embodiment with the surface incident light receiving element 303 used in the present embodiment.

Embodiment 4 FIG. 4 shows an optical module according to a fourth embodiment of the present invention. In the drawing, reference numeral 401 denotes an optical fiber, 402 denotes an optical lens, 403 denotes an end face light receiving element (including a waveguide light receiving element), 403a denotes a signal electrode of the end face light receiving element, and 403b denotes an end face light receiving element. Ground electrode, 404 is a microstrip line, 404
a is a microstrip line signal electrode, 404b is a microstrip line ground electrode, 405 is a coaxial connector, and 406 is a package for fixing these.

In this optical module, the optical fiber 4
The optical signal introduced from 01 is condensed by the optical lens 402 and is incident on the end face incident type light receiving element 403. In the end face incident type light receiving element 403, the incident optical signal is converted into an electric signal, and this electric signal is converted into a microstrip line 40.
4 through the coaxial connector 405 to the outside of the module.

In the optical module of the present embodiment, the end-face incident type light receiving element 403 is arranged laterally on the side of the substrate on the right side of the microstrip line 404 in the drawing. In other words, the signal electrode 403a and the ground electrode 403b respectively formed on the surface of the end face type light receiving element 403 are oblique to the substrate side surface of the microstrip line 404, and the signal electrode 403a is It faces toward the signal electrode 404a, and the ground electrode 4
03b is the signal electrode 40 of the microstrip line 404
It is arranged so as to face the 4b side. In addition, the microstrip line 4 on which the end face type light receiving element 403 is arranged.
A part of the side of 04 is inclined with respect to the incident light.

The conductive paste is connected between the signal electrode 403a and the signal electrode 404a, and between the ground electrode 403b and the signal electrode 404b. Further, in this embodiment, the signal electrode 404a of the microstrip line 404 is connected to the coaxial connector 405 in a region where the signal electrode 404a is connected to the coaxial connector 405.
In a region connected to the end face incident type light receiving element 403, it is bent in the middle so as to be inclined with respect to the coaxial connector 405. As a result, the end of the signal electrode 404a connected to the end face incident type light receiving element 403 is connected to the coaxial connector 405.
And reaches the side of the microstrip line 404 parallel to.

The edge incident type light receiving element 40 shown in this embodiment
In the form of connection between 3 and the line, the end face incident type light receiving element 403 can be connected without changing the shape of the microstrip line 404 even near the connection portion.

In the optical module shown in this embodiment, since light is obliquely incident on the end face light receiving element 403, the light obliquely passes through the light absorption layer in the end face light receiving element 403. As a result, there is an effect that the effective light absorbing layer thickness is increased and the photoelectric conversion efficiency is improved. As a result, the loss of the electric signal due to the impedance mismatch at 20 GHz is reduced from 3 dB of the related art to 0.5 d.
B, and a photoelectric conversion efficiency of about 2
0% improvement was achieved.

In this embodiment, an example in which the end face type light receiving element 403 is used as an optical element has been described. However, the present invention is not limited to this, and other optical elements such as a semiconductor laser or a semiconductor optical modulator may be used. It is also possible to apply to.
It should be noted that the linear microstrip line 303 shown in the third embodiment can be combined with the end face type light receiving element 403 used in this embodiment.

[0035]

As described above in detail with reference to the embodiments, in the present invention, the signal electrodes and the ground electrodes of the optical element are arranged side by side by arranging the optical element on the side of the substrate of the microstrip line. These can be respectively drawn to the signal electrode side and the ground electrode side of the microstrip line. Therefore, it is possible to connect the optical element and the line without processing the microstrip line, that is, without changing the impedance of the microstrip line. There is an advantage that an optical module can be realized.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an optical module according to a first embodiment of the present invention.

FIG. 2 is a perspective view showing an optical module according to a second embodiment of the present invention.

FIG. 3 is a perspective view showing an optical module according to a third embodiment of the present invention.

FIG. 4 is a perspective view showing an optical module according to a fourth embodiment of the present invention.

FIG. 5 is a perspective view showing a conventional optical module.

FIG. 6 is a perspective view showing a conventional optical module.

[Explanation of symbols]

101, 201, 301, 401, 501, 601 Optical fiber 102, 202, 302, 402, 502, 602 Optical lens 103, 203, 303, 403, 503, 603 Light receiving element 103a, 203a, 303a, 403a, 503a,
603a signal electrodes 103b, 203b, 303b, 403b, 503b,
603b Ground electrodes 104, 204, 304, 404, 504, 604 Lines 104a, 204a, 304a, 404a, 504a,
604a signal electrodes 104b, 204b, 304b, 404b, 504b,
604b Ground electrode 504c Through hole 105, 205, 305, 405, 505, 605 Coaxial connector 106, 206, 306, 406, 506, 606 Package

Claims (5)

[Claims] 1. An optical module comprising at least an optical element and a microstrip line, wherein the optical element is disposed laterally on a side surface of a substrate of the microstrip line, and one electrode of the optical element is connected to the microstrip. An optical module, wherein the other electrode is connected to the signal electrode of the line and the ground electrode of the microstrip line. 2. The optical module according to claim 1, wherein
An optical module, wherein a part of the signal electrode of the microstrip line is curved or bent. 3. The optical module according to claim 2, wherein
The end of the signal electrode of the microstrip line connected to the optical element reaches a side not facing the side of the other end of the signal electrode of the microstrip line. Optical module. 4. The optical module according to claim 1, wherein the optical element is a light receiving element. 5. The optical module according to claim 4, wherein
An optical module, characterized in that a side of a signal electrode of the microstrip line reaching a terminal end connected to the optical element is inclined with respect to incident light.