JPH11317566A - Optical module - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain arm optical module which is less affected by the dielectric loss of a silicon board and an electric capacitance generated between the board and electrodes formed on the board, by a method wherein a feeder for a photoelectric conversion device is provided to a feeding board provided onto the silicon board. SOLUTION: Electrodes are provided to a dielectric board 8 other than a silicon board 5 to input electric signals to a semiconductor laser 1. The electrode formed on the underside of the dielectric board 8 is connected to the ground electrode of a photo-element, and the other electrode formed on the upside of the dielectric board 8 is connected to the other electrode of the photo-element. By this setup, the electrode located on the underside of the dielectric board 8 functions as a grounding terminal, an electric field is confined between the grounding electrode and the other electrode located on the upside of the dielectric board 8, so that the semiconductor laser 1 can be less affected by the dielectric loss of the silicon board 5 and an electric capacitance generated between the silicon board 5 and electrodes formed on the board 5. The dielectric board 8 is completely separated from the silicon board 5, so that a light module can be manufactured through a simple manufacturing process.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical module used for an optical communication system.

[0002]

2. Description of the Related Art The structure of a conventional optical module will be described.
FIG. 4 is a configuration diagram of a conventional optical module disclosed in Japanese Patent Application Laid-Open No. 8-78657. In the figure, 1 is a semiconductor laser, 3 is an optical waveguide, 5 is a silicon substrate, 7 is a ground electrode of the semiconductor laser 1, 11 is a marker on the silicon substrate 5, and 12 is a marker on the corresponding semiconductor laser 1. 27 is a glass dielectric layer formed in the concave portion of the silicon substrate 5, 28 is an electrode formed on the glass dielectric layer, 29 is a lower cladding of the optical waveguide 3, and 30 is an optical waveguide 3
The upper cladding. FIG. 5 shows a process of manufacturing a silicon substrate used in the conventional optical module shown in FIG. In the figure, 31 is a flat silicon substrate, 32 is a silicon substrate provided with irregularities by etching the silicon substrate 31, 33 is a substrate on which quartz glass serving as a lower clad is deposited, and 34 is the surface of the silicon substrate 33 polished. A substrate 35 is a substrate on which the optical waveguide 3 and a quartz substrate 30 serving as an upper clad of the optical waveguide are deposited. Others are the same as those in FIG.

[0003] A state until the light of the optical module is emitted to the transmission line will be described. The electric signal propagates through the ground electrode 7 and the inner conductor electrode 28 formed on the glass dielectric layer, and is input to the semiconductor laser 1. In the semiconductor laser 1, an input electric signal is converted into an optical signal and emitted. The light emitted from the semiconductor laser 1 is coupled to the optical waveguide 3 and further coupled to the optical fiber 2 and guided to the transmission line optical fiber of the optical communication system. The following is considered in the configuration for improving the efficiency of the optical module.
The semiconductor laser 1 is mounted such that the marker 11 formed on the silicon substrate 5 and the marker 12 formed on the semiconductor laser 1 coincide with each other.
It can be mounted with high precision on top and can be optically coupled to an optical waveguide. Since the silicon substrate 5 has excellent heat conductivity and well escapes the heat of the optical device, and it is easy to form a precise marker using a semiconductor process and to form a precise V-groove for mounting an optical fiber, Used for seed substrates. However, since silicon is a semiconductor material, firstly, the material itself has a resistance component on the Si substrate,
Transmission loss of a high-frequency microwave signal increases. Second
When a conductive line is formed, an insulating film must be formed to insulate the silicon substrate from the silicon substrate. However, there is a disadvantage that a large capacitance is generated due to the configuration of the Si substrate / insulating film / conductive line.

FIG. 5 shows a process of manufacturing a silicon substrate used in the conventional optical module shown in FIG. First, a flat silicon substrate 31 is formed with irregularities by etching to produce a silicon substrate 32 having irregularities.
Next, a silicon substrate 33 which is a lower clad of the optical waveguide 3 and on which a silica-based glass dielectric for forming a power supply electrode for the semiconductor laser is deposited is manufactured. Further, the silicon substrate 33 is polished to make the surface smooth.
After the fabrication of the optical waveguide 4, an optical waveguide and a silica glass dielectric layer serving as an upper clad of the optical waveguide are deposited (the silicon substrate 3).
5). Finally, etching is performed to expose the semiconductor laser mounting portion of the silicon substrate 35 and the electrode forming portion,
A silicon substrate with an optical waveguide 5 on which a semiconductor laser is mounted is obtained. In this way, since the electrodes 7 and 28 are formed on the glass dielectric layer having a sufficient thickness, the influence of the dielectric loss of the silicon substrate itself and the gap between the silicon substrate and the electrodes formed on the silicon substrate are obtained. The effect of the generated electric capacity can be reduced.

[0005]

As described in the manufacturing process of FIG. 5, the conventional silicon substrate of the optical module has a problem that a complicated manufacturing process is required and the optical module becomes expensive. Further, the conventional optical module is assembled so that the marker provided on the optical element and the marker provided on the silicon substrate are aligned, and the optical element and the optical waveguide are aligned and optically coupled. But,
Since the mask for forming the marker and the mask for forming the optical waveguide are different, there has been a problem that it is difficult to perform high-precision position adjustment due to errors in the mask itself and errors in the aligner. Further, after exposing the optical element mounting portion by etching, a mask pattern for attaching a gold pattern is applied to the marker on the silicon substrate while avoiding the residual upper clad, thereby forming a gold pattern. However, there is a problem that it is difficult to form a mark with high accuracy because the mask pattern floats from the silicon substrate due to the presence of the upper cladding. Further, the conventional optical module can be connected to the optical fiber without adjustment by forming the V-groove portion at the tip of the optical waveguide portion. However, since the conventional optical module can form the optical waveguide and the mask for forming the V-groove portion. However, there is a problem that high-precision position adjustment is difficult due to errors in the mask itself and errors in the aligner. In the case where the V-groove portion is formed simultaneously with the formation of the concavo-convex portion of the silicon substrate, the amount of polishing in the subsequent polishing step of the silicon substrate must be controlled with high precision. In the case of forming, there is a problem that it is difficult to form a mark with high precision because the mask pattern for forming the V-groove floats from the silicon substrate due to the presence of the upper cladding. Furthermore, the conventional optical module has a problem that an optical isolator cannot be inserted into the optical module because a lens optical system is not used for optical coupling.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problem, and a complicated manufacturing process is not required for a silicon substrate by using a substrate different from the substrate, and the element is accurately manufactured. It is an object of the present invention to provide an optical module that can be assembled and that can further insert an element for improving performance.

[0007]

An optical module according to the present invention comprises a light conversion element and a silicon substrate on which the light conversion element is mounted, wherein a power supply substrate different from the silicon substrate is provided on the silicon substrate. Thus, a power supply line to the light conversion element was provided on the power supply substrate.

Furthermore, a ground electrode is provided on the side of the silicon substrate in contact with the power supply substrate or on the side of the power supply substrate in contact with the silicon substrate.

Further, a package surrounding the light conversion element and the power supply board is provided, and this package is provided with a ground electrode on the side in contact with the light conversion element and the power supply board.

Alternatively, in a configuration including a light conversion element and a silicon substrate on which the light conversion element is mounted, an optical waveguide substrate different from the silicon substrate is provided on the silicon substrate, and the optical waveguide is provided on the optical waveguide substrate. Formed.

Still further, a marker for positioning the light conversion element and a marker for positioning the optical waveguide substrate are simultaneously formed on the silicon substrate.

Further, a groove for installing an optical fiber is provided on a side of the optical waveguide substrate on the silicon substrate which is different from the optical conversion element side, and a marker for positioning the optical waveguide substrate for bonding with the optical fiber is also made of silicon. They were formed simultaneously on the substrate.

Further, a groove for installing an optical fiber is provided on a side of the optical waveguide substrate on the silicon substrate which is different from the optical conversion element side, and an optical isolator and an optical isolator are provided on a light sending side of the optical fiber different from the optical waveguide side. Alternatively, a protective plate having a refractive index substantially equal to that of the optical fiber was provided.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment 1 A description will be given of a configuration in which another intermediate substrate is introduced on a silicon substrate in order to eliminate a complicated manufacturing process for an electric circuit, and a positional relationship is maintained with accuracy. FIG. 1 is a diagram illustrating a configuration of an optical module according to the present embodiment. In the figure, 1 is a semiconductor laser as a light source, 2 is an optical fiber for guiding light emitted from the semiconductor laser 1 to a transmission line of an optical communication system, and 3 is an optical waveguide for guiding light emitted from the semiconductor laser 1 to an optical fiber. 4, a substrate on which the optical waveguide 3 is formed; 5, a silicon substrate on which the semiconductor laser 1, the optical fiber 2, and the substrate 4 are mounted; and 6, a V for mounting the optical fiber 2 formed on the silicon substrate 5.
The groove, 7 is a ground-side electrode of the semiconductor laser 1, 8 is another dielectric substrate different from the silicon substrate 5, 9 is an electrode formed on the dielectric substrate 8, and 10 is to conduct the ground-side electrode 7 and the electrode 9. , A marker 11 on the silicon substrate 5 to be referred to when the semiconductor laser 1 is mounted, 12 a marker on the semiconductor laser 1 formed to match the marker 11 when the semiconductor laser 1 is mounted, 13 Are referred to when mounting the substrate 4 on which the optical waveguide is formed, and the markers 14 and 14 on the silicon substrate 5 having a predetermined positional relationship with the marker 11
Is a marker 13 when mounting the substrate 4 on which the optical waveguide is formed.
The marker 15 on the substrate 4 formed so as to match with the silicon substrate 5 having a predetermined positional relationship with the V groove 6 for mounting an optical fiber, which is referred to when mounting the substrate 4 on which the optical waveguide is formed. The upper marker 16 is a marker on the substrate 4 formed to match the marker 15 when mounting the substrate 4 on which the optical waveguide is formed.

Next, the operation of the module from the input to the electric circuit to the output to the optical transmission line will be described. The electric signal is transmitted to the dielectric substrate 8 mounted on the silicon substrate 5.
And transmitted to the semiconductor laser 1. The electrode 9 includes a ground electrode 9a and a non-ground electrode 9b. The ground electrode 9a is connected to the ground electrode 7 of the semiconductor laser 1 by a through hole 10, and the electrode 9b is connected to the other electrode of the semiconductor laser. ing. The input electric signal is converted into an optical signal by the semiconductor laser 1 and emitted. The light emitted from the semiconductor laser 1 is coupled to an optical waveguide 3 and further transmitted to an optical fiber 2.
And guided to the transmission line optical fiber of the optical communication system.

Next, the accuracy of the assembly configuration will be described. First, it is necessary that the optical signal output from the semiconductor laser 1 is correctly transmitted to the optical fiber with little loss. This matching is performed on the common silicon substrate 5. The semiconductor laser 1 includes a marker 11 formed on a silicon substrate 5.
By mounting so that the markers 12 formed on the semiconductor laser 1 coincide with each other, the mounting can be performed on the silicon substrate 5 with high accuracy. That is, there is no influence on the positional accuracy (accuracy) of another dielectric substrate 8. Also,
The optical fiber 2 can be mounted on the silicon substrate without adjustment by placing it on the V-groove 6 formed on the silicon substrate 5.

Here, the input of an electric signal to the semiconductor laser 1 uses a dielectric substrate 8 having electrodes formed thereon, which is different from the silicon substrate. For example, it is formed on the lower surface of the dielectric substrate 8. By connecting the electrode to the ground of the optical element and connecting the electrode formed on the upper surface of the dielectric substrate 8 to the other electrode of the optical element, the electrode on the lower surface of the dielectric substrate 8 functions as the ground, The electric field is confined between the electrode formed on the upper surface of the silicon substrate 8 and the effect of dielectric loss of the silicon substrate itself and the effect of electric capacitance generated between the silicon substrate 5 and the electrode formed on the silicon substrate. Can be. In addition, since the dielectric substrate 8 is a completely different substrate from the silicon substrate 5, the silicon substrate only needs to form a V-groove for mounting an optical fiber, and the manufacturing process of the optical module is simplified. Instead of providing the ground electrode 7 on the silicon substrate 5, a ground electrode may be provided on the silicon substrate side of the dielectric substrate 8. In addition, the formation of the marker on the silicon substrate 5 for mounting the semiconductor laser 1 and the substrate 4 for forming the optical waveguide on the silicon substrate 5 with high positional accuracy is performed together with the same mask pattern as in the V-groove forming step. It can be manufactured by etching. Therefore, the process is simplified, and the positions of the semiconductor laser, the optical waveguide, and the optical fiber can be adjusted with high accuracy, and an optical module with good coupling efficiency can be obtained. Note that the dielectric substrate 8
For example, a substrate generally used as a transmission line substrate for high-frequency electric signals, such as alumina ceramic, can be used.

Further, since the optical waveguide 3 for guiding the light emitted from the semiconductor laser 1 is formed on a substrate 4 different from the silicon substrate 5 on which the semiconductor laser 1 is mounted, the optical waveguide 3 is independent of the silicon substrate 5. The optical waveguide 3 can be formed, and the manufacturing process of the optical module is simplified. Also, the optical waveguide 3
May be any of a raised type, a ridge type, a loaded type, and a diffusion type. Since the surface of the substrate 4 is processed to form the groove of the optical waveguide 3, it is easy to manage the height direction of the optical waveguide. That is, it is easy to make the heights of the semiconductor laser 1 in the optical signal output direction equal, and the coupling efficiency of the optical module can be increased. In addition, since the substrate 4 different from the silicon substrate 5 was used for forming the optical waveguide, another demultiplexing mechanism, a wavelength discriminating mechanism, a multiplexing mechanism, and the like were mounted on the substrate 4 to achieve a high function. It is also possible.

Further, a marker 13 is provided on the silicon substrate 5 so as to have a predetermined positional relationship with a marker 11 for mounting the semiconductor laser 1, and a V for mounting the optical fiber 2 is provided. The marker 15 is provided so as to have a predetermined positional relationship with the groove 6. On the other hand, the substrate 4
A marker 14 having a predetermined positional relationship with the optical waveguide 3 is provided on the semiconductor laser 1 side of the optical waveguide, and a marker 16 having a predetermined positional relationship with the optical waveguide 3 is provided on the optical fiber 2 side of the optical waveguide.
Is provided. Thus, the common silicon substrate 5
With reference to the above, markers as position information that match the elements installed facing each other are obtained in the same process, and high accuracy is guaranteed. In this way, the semiconductor laser 1 and the optical waveguide 3 are mounted by mounting the substrate 4 so that the marker 13 and the marker 14 match and the marker 15 and the marker 16 match.
The optical waveguide 3 and the optical fiber 2 coincide with each other, and the light emitted from the semiconductor laser 1 can be guided to the transmission line optical fiber 2 with high efficiency.

Although the present embodiment has been described using a semiconductor laser as the optical element, it may be a photodiode.

Embodiment 2 FIG. In the present embodiment,
A configuration in which the influence of the surroundings on the input-side electric circuit will be described. FIG. 2 is a diagram illustrating a configuration of the optical module according to the present embodiment. In the figure, reference numeral 17 denotes a package for maintaining a hermetic seal, incorporating a silicon substrate on which a semiconductor laser 1, an optical fiber 2, a substrate 4 on which an optical waveguide is formed, and a dielectric substrate 8 are mounted. Reference numeral 18 denotes a ground electrode 7 of the silicon substrate. A ground of a package formed so as to surround and connect to the electrode 7, 19 is an electrode formed on a package for supplying an electric signal to an electrode other than the ground of the semiconductor laser 1, 20 is an electrode 7 and the ground electrode 1 of the package.
8 is a gold ribbon for connecting the electrode 8, 21 is a gold wire for electrically connecting an electrode that is not the ground of the semiconductor laser 1 to the electrode 9 formed on the dielectric substrate, and 22 is an electrode formed on the dielectric substrate. 9 is a gold wire for connecting the electrode 9 and the electrode 19 formed on the package. The other elements with the same numbers are the same as the elements with the same numbers shown in FIG.

Next, the operation will be described. The electric signal input to the package propagates using the package electrode 18 as a ground and the package electrode 19 as an inner conductor. The ground of the package is connected to the ground of the semiconductor laser 1 via a gold ribbon 20, the electrode 19 is connected to the electrode 9 formed on the dielectric substrate 8 via a gold wire 22, and the gold wire 21 Is connected to an electrode other than the ground of the semiconductor laser 1 via an input terminal, and an input electric signal is input to the semiconductor laser 1. In the semiconductor laser 1, an input electric signal is converted into an optical signal and emitted. Light emitted from the semiconductor laser 1 is coupled to an optical waveguide formed on the substrate 4, further coupled to the optical fiber 2, and guided to a transmission line optical fiber of an optical communication system.

Here, as shown in FIG. 2, if the ground electrode 7 of the semiconductor laser 1 and the ground electrode 18 of the package are brought close to each other and electrically connected firmly with a gold ribbon or the like,
As in the first embodiment, even if an electrode for a ground conductor is not formed on the substrate 8 itself, the influence of the dielectric loss of the silicon substrate itself and the electric potential generated between the silicon substrate and the electrodes formed on the silicon substrate are eliminated. The effect of the capacity can be reduced.

Further, since the ground electrode 18 of the package is formed close to and surrounds the silicon substrate 5, it can be used as a guide when the silicon substrate 5 is built in the package, and can be used for assembly. An easy optical module can be obtained.

Embodiment 3 An optical module which does not require a complicated process on a silicon substrate serving as a common substrate, and in which an optical isolator and various functional elements can be inserted and a flexible optical path can be formed will be described. FIG. 3 is a diagram showing a configuration of the optical module according to the present embodiment. In the figure, 23 is a ferrule holding the optical fiber 2,
Reference numeral 24 denotes a connector part of the optical module for connecting the optical fiber 2 and the transmission line optical fiber, and 25 denotes a connector part.
, One of which is optically in contact with or adhered to the optical fiber 2, and 26 is an optical plate having a refractive index substantially equal to the refractive index of the optical fiber provided on the transmission line optical fiber side of the optical isolator. The other numbered elements are
It is the same as the corresponding number in FIGS. 1 and 2 already described.

Next, the operation will be described. The electric signal is input to the semiconductor laser 1, converted into an optical signal, and emitted. Light emitted from the semiconductor laser 1 is coupled to an optical waveguide formed on a substrate 4, further coupled to an optical fiber 2, transmitted through an optical isolator, and guided to a transmission line optical fiber of an optical communication system. Since the optical isolator is provided between the optical fiber 2 and the transmission line optical fiber, the reflected return light from the transmission line optical fiber can be shielded, and the oscillation characteristics of the semiconductor laser 1 can be stabilized.

The optical isolator 25 is built in the connector section 24 of the package, and forms a small optical module with a built-in optical isolator. The optical isolator and the optical fiber 2 can be reduced in reflection at the interface by optically contacting (physical contact) or bonding after applying an anti-reflection coating to the optical isolator. Similarly, in the connection between the optical isolator 25 and the transmission line optical fiber, reflection can be reduced by optically contacting the optical isolator after applying a non-reflective coating to the optical isolator.

Further, an optical plate having a refractive index substantially equal to that of the transmission line optical fiber is provided on the side of the transmission line optical fiber of the optical isolator. It is possible to prevent the isolator from being applied and to improve reliability.

[0029]

Since the present invention is configured as described above, it has the following effects. Since an electrode is formed on a dielectric substrate 8 different from the silicon substrate for inputting an electric signal to the semiconductor laser 1 and a ground electrode is provided on the lower surface of the dielectric substrate 8, the dielectric loss of the silicon substrate itself is reduced. And the effect of the electric capacitance generated between the silicon substrate and the electrodes formed on the silicon substrate can be reduced, and an excellent high-frequency response characteristic can be obtained.

Further, since the dielectric substrate 8 is a substrate different from the silicon substrate 5, there is also an effect that the manufacturing process of the silicon substrate is simplified.

Further, the marker on the silicon substrate for accurately mounting the substrate on which the semiconductor laser and the optical waveguide are formed on the silicon substrate is also manufactured by etching together with the same mask pattern as in the V-groove forming step. Therefore, there is also an effect that the manufacturing process is simplified.

Furthermore, the position of the semiconductor laser, the optical waveguide, and the optical fiber can be adjusted with high precision, and an optical module having good coupling efficiency can be obtained.

Further, since the optical isolator can be built in the connector portion of the package behind the optical fiber, there is an effect that a small optical module with a built-in optical isolator can be easily obtained.

Further, since an optical plate having a refractive index substantially equal to that of the transmission path optical fiber is provided on the transmission path optical fiber side of the optical isolator, a force when the transmission path optical fiber is connected by the connector is applied to the optical isolator. Can be prevented, and there is also an effect of increasing reliability.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of an optical module according to Embodiment 1 of the present invention.

FIG. 2 is a configuration diagram of an optical module according to Embodiment 2 of the present invention.

FIG. 3 is a configuration diagram of an optical module according to Embodiment 3 of the present invention.

FIG. 4 is a configuration diagram of a conventional optical module.

FIG. 5 is an explanatory view of a manufacturing process of a conventional optical module.

[Explanation of symbols]

1 semiconductor laser, 2 optical fiber, 3 optical waveguide, 4
Substrate on which optical waveguide is formed, 5 silicon substrate, 6 V
Groove, 7 ground electrode, 8 dielectric substrate, 9 electrode on dielectric substrate, 10 through hole, 11 marker on silicon substrate, 12 marker on semiconductor laser, 13 marker on silicon substrate, 14 marker on substrate 4 , 15
Marker on silicon substrate, 16 Marker on substrate 4, 1
7 package, 18 package ground electrode, 1
9 package electrode, 20 gold ribbon, 21 gold wire, 22 gold wire, 23 ferrule, 24 package connector, 25 optical isolator, 26 optical plate, 27 glass dielectric layer, 28 electrode on dielectric layer,
29 lower clad, 30 upper clad, 31 flat silicon substrate, 32 silicon substrate having irregularities, 33
A silicon substrate having a glass dielectric layer deposited thereon, a silicon substrate having a polished surface, and a silicon substrate having an optical waveguide and an upper clad formed thereon.

Claims (7)

[Claims] In a configuration comprising a light conversion element and a silicon substrate on which the light conversion element is mounted, a power supply substrate different from the silicon substrate is provided on the silicon substrate, and the light conversion substrate is provided on the power supply substrate. An optical module comprising a power supply line to an element. 2. The method according to claim 1, wherein the silicon substrate is in contact with a power supply substrate.
2. The optical module according to claim 1, wherein a ground electrode is provided on a side of the power supply substrate in contact with the silicon substrate. 3. The package according to claim 1, wherein a package surrounding the light conversion element and the power supply board is provided, and the package has a ground electrode on a side contacting the light conversion element and the power supply board. An optical module as described. 4. In a configuration comprising a light conversion element and a silicon substrate on which the light conversion element is mounted, an optical waveguide substrate different from the silicon substrate is provided on the silicon substrate, and an optical waveguide is provided on the optical waveguide substrate. An optical module, wherein a wave path is formed. 5. The optical module according to claim 4, wherein a marker for positioning the light conversion element and a marker for positioning the optical waveguide substrate are simultaneously formed on the silicon substrate. 6. The optical waveguide substrate on the silicon substrate is provided with a groove for installing an optical fiber on a side different from the optical conversion element side, and a marker for positioning the optical waveguide substrate for bonding with the optical fiber is also provided. The optical module according to claim 4, wherein the optical module is formed simultaneously on the silicon substrate. 7. An optical fiber installation groove is provided on a side of the optical waveguide substrate on the silicon substrate which is different from the optical conversion element side, and an optical isolator or The optical module according to claim 4, further comprising a protective plate having a refractive index substantially equal to that of the optical fiber.