JP2004251976A - Optical module - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress an increase in cost of parts and to facilitate positioning even when a lens body is inserted into an optical path to increase an optical coupling efficiency of an optical transmission path to an optical semiconductor element. <P>SOLUTION: This optical module formed by optically coupling the optical semiconductor element to the optical transmission path is provided with: a substrate 10 having a slope 13 between a first face 11 and a second face 12 lower than the face 11; a reflection mirror 30 having a dimple 18 at a part of the slope 13 and formed inside the dimple 18; a hemispherical lens 40 formed on the slope 13 covering the reflection mirror 30, and positioned by the dimple 18; optical fibers 20 provided on the second face 12, with the optical path direction set parallel to the substrate surface and disposed so that the reflection mirror 30 is positioned in the extending direction of the optical path; and a light receiving element 50 provided on the first face 11, with a light incident direction set vertical to the substrate surface, and on which the reflected light from the reflection mirror 30 is made incident. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an optical module used for optical communication, optical transmission technology, and optical information recording technology, and particularly to an optical module for coupling an optical semiconductor element and an optical transmission line.
[0002]
[Prior art]
2. Description of the Related Art In recent years, in optical communication, optical transmission, optical information recording technology, and the like, transmission of a signal using light as a carrier wave by intensity modulation, phase modulation, or the like has been widely used. For such optical transmission, an optical coupling device for optically coupling an optical semiconductor element such as a light emitting element or a light receiving element to an optical transmission line such as an optical fiber is required.
[0003]
In this type of device, as the speed of an optical signal to be handled increases, the electrical parasitic capacitance of the light emitting element and the light receiving element cannot be ignored, and the size of the active layer or the light receiving area of the element has become smaller. For example, the diameter of the light receiving surface of a GaAs pin photodiode has been reduced to about 40 to 50 μm in order to obtain a response of 10 GHz or more. Therefore, when the output light from the multi-mode optical fiber is input to the light receiving element, the light coupling efficiency is reduced due to the spread of the beam and the like, and a problem arises that the noise resistance is deteriorated and the transmission distance cannot be increased. .
[0004]
Further, it is necessary to insert a lens into the optical path in order to increase the tolerance of the relative position between the optical semiconductor element and the optical fiber. However, there is a problem that insertion of a lens increases the number of components, making positioning more difficult, and mounting costs tend to increase.
[0005]
Therefore, techniques for reducing mounting costs by techniques such as component integration and self-alignment techniques have been actively researched and developed. For example, as an optical coupling technique between an optical fiber and a light emitting element or a light receiving element, there is the following example.
[0006]
As a first example, there is a light receiving module that causes light incident from an optical fiber to enter a semiconductor lens or a flat microlens, emits light downward by changing the optical path on a reflection surface, and enters the light receiving region of a light receiving element. However, in this configuration, it is necessary to position and fix the optical fiber, the lens, and the light receiving element, and there is a problem that mounting cost is increased (for example, see Patent Document 1).
[0007]
As a second example, there is an optical coupling member that makes light incident on an optical fiber fixed in a V-groove formed on a silicon substrate, and makes light reflected by a slope formed on the silicon substrate incident on a light receiving element. . The element bottom surface of the light receiving element has a lens, and the light beam is condensed and enters the light absorption region. Since the light receiving element is flip-chip mounted on a pad formed on the silicon substrate, the positions of the optical fiber, the reflection surface, and the light receiving element are determined in a self-aligned manner, and the mounting cost is reduced.
[0008]
However, this configuration has a structure in which a lens for condensing light is integrated on the bottom surface of the light receiving element, and it is necessary to adjust the thickness of the light receiving element and the curvature of the lens according to the design. Further, since it is difficult to form a pressure lens by reducing the curvature of the lens, it is difficult to obtain a sufficient beam refraction. Therefore, the efficiency of light collection tends to be low. In addition, since the light receiving element and the electrode are provided on the front surface of the light receiving element and the lens is provided on the rear surface, special care is required for handling the element, and there is a problem that the mounting cost is hardly reduced after all (for example, see Patent Document 2).
[0009]
As a third example, there is a laser light emitting device that reflects and condenses light emitted from a semiconductor laser chip by a concave rising mirror formed in a block, and outputs the light as an externally focused light beam. In this configuration, the astigmatic difference of the beam can be corrected by forming the concave rising mirror only in the major axis direction of the laser beam. However, in this configuration, it is necessary to increase the curvature of the concave portion for condensing the beam. However, when the concave portion is manufactured by machining such as cutting, it is difficult to control the shape and secure the positional accuracy. Further, in the case of chemically processing by etching or the like, precise control of etching and a long process time are required, and in any case, there is a problem that the cost increases (for example, see Patent Document 3).
[0010]
As a fourth example, there is an optical module that realizes a thin optical module by integrating a hemispherical lens on a mirror. In this case, by integrating the mirror and the hemispherical lens, the number of parts is reduced and the handleability is improved, and the refraction by the lens can be used twice as in the case where the mirror and the hemispherical lens are used as usual. Therefore, a sufficient light-collecting effect can be obtained. However, in this configuration, since the mirror-integrated lens is assembled in the package housing, the optical axis adjustment and the like depend on the accuracy of the package member and the assembly, the effective diameter of the active area of the optical element becomes small, and the tolerance is reduced. As the size becomes smaller, high accuracy is required for package members and assemblies, and there is a problem that cost increases and high-speed operation becomes difficult (for example, see Patent Document 4).
[0011]
[Patent Document 1]
JP-A-5-273444
[Patent Document 2]
JP-A-6-275870
[Patent Document 3]
JP-A-11-214797
[Patent Document 4]
JP-A-2002-243990
[Problems to be solved by the invention]
As described above, conventionally, if a lens body is inserted into an optical path in order to increase the optical coupling efficiency between an optical transmission line and an optical semiconductor element, the cost of parts is increased, and high mounting accuracy is required. Had the problem of rising.
[0016]
The present invention has been made in view of the above circumstances, and an object of the present invention is to increase the coupling efficiency by inserting a lens between an optical transmission line and an optical semiconductor element, and to improve optical transmission. It is an object of the present invention to provide an optical module that can easily be positioned between a path and an optical semiconductor element and can be manufactured at low cost.
[0017]
[Means for Solving the Problems]
(Constitution)
In order to solve the above problems, the present invention employs the following configuration.
[0018]
That is, the present invention provides an optical module having a substrate having a step on the surface side, a slope formed on the step, a hemispherical lens formed on a part of the slope, and a bottom surface of the hemispherical lens. A reflector formed on at least a part of a boundary between the reflector and the slope, and a reflector provided on a part of the substrate and irradiating light to the reflector in an oblique direction, or receiving reflected light from the reflector. Wherein the slope has a depression, and at least a part of the bottom of the hemispherical lens is in the depression.
[0019]
The present invention also provides an optical module having a stepped portion on the front surface side, a substrate having a slope formed on the stepped portion, a hemispherical lens formed on a part of the slope, and a bottom surface of the hemispherical lens. And a reflecting mirror formed on at least a part of the boundary of the slope, and provided on a part of the substrate, an optical path direction is defined in a direction parallel to the substrate surface, and the reflecting mirror is positioned in an extending direction of the optical path. Wherein the slope has a depression, and at least a part of the bottom of the hemispherical lens is in the depression.
[0020]
The present invention also provides a substrate having a slope between a first surface and a second surface having a height lower than the first surface, a hemispherical lens formed on a part of the slope, A reflecting mirror formed on at least a part of a boundary between the bottom surface and the slope; and a reflecting mirror provided on the second surface of the substrate, wherein an optical path direction is defined in a direction parallel to the substrate surface, and the reflecting mirror extends in an extending direction of the optical path. An optical transmission line disposed so as to be positioned, and provided on a first surface of the substrate, an emission direction or an incidence direction of light is defined in a direction perpendicular to the substrate surface, and the light is transmitted obliquely with respect to the reflecting mirror. Or an optical semiconductor element to which the reflected light from the reflecting mirror is incident, wherein the optical semiconductor element and the optical transmission path are converted into light by the conversion of the optical path by the reflecting mirror. The slope has a depression, and the hemispherical At least a portion of the bottom of the figure is characterized in that in said recess.
[0021]
Here, preferred embodiments of the present invention include the following.
[0022]
(1) The reflectance of the reflector has wavelength dependence or polarization dependence.
[0023]
(2) The substrate is made of silicon, and the slope is made of the (111) plane of the substrate.
[0024]
(3) The optical transmission path is an optical fiber and is positioned and held in a V-groove provided in the substrate.
[0025]
(4) A plurality of hemispherical lenses and reflecting mirrors are provided according to the number of optical semiconductor elements and optical transmission paths.
[0026]
(Action)
According to the present invention, the position of the hemispherical lens can be positioned by a recess formed in advance, and the assembly position of each component can be assembled with reference to a substrate using a semiconductor process. The relative position between the element or the optical transmission path and the lens and the reflecting mirror can be positioned with high accuracy without adjustment. Here, in the case of a hemispherical lens, light passes through the lens interface twice, and the lens effect becomes large. Therefore, a sufficiently large focusing effect can be obtained.
[0027]
In addition, since a hemispherical lens can be easily manufactured using a surface tension or the like without complicated machining or etching, it is possible to suppress an increase in component costs. Further, the positions of the hemispherical lens and the reflecting mirror can be determined by the recess formed in advance, and positioning for optical coupling becomes easy. Therefore, it is possible to reduce the manufacturing cost.
[0028]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the present invention will be described in detail with reference to the illustrated embodiments.
[0029]
(1st Embodiment)
FIGS. 1A and 1B are diagrams for explaining a schematic configuration of an optical module (optical semiconductor device) according to a first embodiment of the present invention, wherein FIG. 1A is a sectional view, and FIG. 1B is a partial perspective view.
[0030]
In the figure, reference numeral 10 denotes a Si substrate, and a surface side of the substrate 10 is partially removed to form a concave portion. An inclined surface 13 inclined at 45 ° is formed at a step between an uppermost surface (first surface) 11 and a concave bottom surface (second surface) 12 of the substrate 10. A plurality of V-shaped grooves 15 are formed in the concave bottom surface 12 in a direction parallel to the substrate surface and orthogonal to the step. Here, the concave portion, the slope 13 of the step portion, the V groove 15 and the like can be formed by anisotropic etching. For example, the slope 13 and the V-groove 15 can be easily formed by anisotropic etching using KOH or the like.
[0031]
An optical fiber (optical transmission path) 20 is positioned and fixed in the V groove 15. A depression 18 is provided on the slope 13 at a position corresponding to the optical axis of the optical fiber 20, and a reflecting mirror 30 is formed in the depression 18. A hemispherical lens 40 is formed so as to cover the reflecting mirror 30. That is, the reflecting mirror 30 is formed on the boundary surface between the bottom surface of the hemispherical lens 40 and the slope 13 (the bottom surface of the depression 18). Here, the size of the bottom of the hemispherical lens 40 is larger than that of the reflecting mirror 30, but the size of the bottom of the hemispherical lens 40 may be the same as that of the reflecting mirror 30. Further, the size of the bottom portion of the hemispherical lens 40 may be smaller than that of the reflecting mirror 30, and the hemispherical lens 40 may be formed only on the reflecting mirror 30.
[0032]
When a plurality of V-grooves 15 are provided and the optical fibers 20 are fixed in the respective grooves, a plurality of reflecting mirrors 30 and hemispherical lenses 40 are also provided according to the number of the optical fibers 20. I have.
[0033]
After forming the slope 13 by anisotropic etching, the depression 18 is opened again in a mask material (an oxide film, a nitride film, or the like) so that silicon is exposed only at a desired position, and is again anisotropic with KOH or the like. It is formed by performing etching. The depression 18 is added for the purpose of positioning the lens 40 by surface tension when the hemispherical lens 40 is formed. The positioning is performed by the recesses 18 to enable the fabrication by a batch process.
[0034]
Reference numeral 50 in the figure denotes a front-illuminated light receiving element such as a photodiode. The light receiving element 50 is flip-chip mounted on a pad 16 formed on the uppermost surface 11 of the substrate 10. The light receiving region 51 of the light receiving element 50 faces downward, and is located above the reflecting mirror 30.
[0035]
The light that has propagated through the optical fiber 20 is emitted at the end face and emitted at an emission angle determined by the waveguide refractive index distribution of the optical fiber 20. The emitted light beam is refracted and condensed on the surface of the hemispherical lens 40 and is reflected by the reflecting mirror 30. The light beam reflected by the reflecting mirror 30 is refracted again by the surface of the hemispherical lens 40, condensed, directed upward, and incident on a light receiving region 51 formed on the surface of the light receiving element 50. Since the hemispherical lens 40 can be formed on a slope by surface tension or the like, it has a substantially spherical surface and can have a small radius of curvature.
[0036]
FIG. 2 shows an example of a schematic method of forming the hemispherical lens 40. In this figure, only a part of the slope 13 of the substrate 10 is shown, and the slope 13 is virtually arranged in the horizontal direction.
[0037]
As shown in FIG. 2A, a reflecting mirror 30 is formed in advance at the bottom of the depression 18. First, a predetermined amount of the resin 41 before solidification is dispensed by the ink jet method or the like in a form of being raised in the recess 18. In the figure, 45 is a nozzle.
[0038]
Next, as shown in FIG. 2B, the resin 41 provided in the recess 18 is heated to be shaped into a hemisphere by surface tension. In other words, the material is prevented from flowing out by the depression 18, and the positioning is performed during the curing due to the difference in surface tension between the slope flat portion and the edge of the depression 18. Further, since this structure can be applied even when the fluidity of the resin 41 is high, it is possible to further expand the range of material selection.
[0039]
In this method, the positioning can be defined by using photolithography, so that a pattern can be formed at a desired position with high precision, and furthermore, it can be manufactured at a low cost because it can be manufactured collectively. Further, by forming the reflecting mirror 30 on the bottom surface of the hemispherical lens 40, the light is refracted twice on the lens surface, so that a lens effect almost equivalent to that of a spherical lens can be obtained.
[0040]
Further, since the light receiving element 50 can be flip-chip mounted on the pad 16 formed on the substrate 10, it can be mounted without adjustment by a self-alignment effect, and the optical fiber 20 can be mounted on the V groove 15 formed on the substrate 10. By fixing, the position in a plane perpendicular to the optical axis can be positioned without adjustment. Furthermore, since the position of the hemispherical lens 40 can be positioned from the recess formed in advance, the relative position of each component can be positioned with high accuracy without adjustment. In addition, since the light receiving element 50 can be surface-mounted by using the reflecting mirror 30, the structure is highly compatible with mounting on an external driving LSI or mounting board.
[0041]
Therefore, it is possible to realize an optical module that can mount components without adjustment and can mount a lens that can obtain refraction at a high magnification. Since high-speed response is possible, high coupling efficiency can be obtained even when the light receiving area of the light receiving element is small, and a device excellent in noise resistance can be realized at low cost.
[0042]
The above optical module can be realized as follows. The slope 13 is formed by anisotropically etching the silicon substrate 10 with KOH or the like using the oxide film or the nitride film as a mask. At this time, a surface having a low etching rate is selectively exposed on the slope 13. For example, by using a substrate whose main surface is 9.7 ° off from the (100) surface, the inclined (111) surface can be set at an angle of 45 ° with respect to the main surface. Thereafter, only the desired position of the slope 13 is again subjected to anisotropic etching with KOH or the like to form the depression 18.
[0043]
Subsequently, after forming a V-groove 15 for mounting the optical fiber 20 in the same manner, an insulating film such as an oxide film is formed on the surface, and etching, lift-off, or plating using ordinary photolithography is performed. A pad 16 for mounting a light receiving element, a solder bump, and the like are formed. Subsequently, a reflecting mirror 30 of Au or the like is formed at a predetermined position on the slope by a lift-off method or the like. At this time, the formation of the pad 16 and the formation of the reflecting mirror 30 may be performed simultaneously.
[0044]
Thereafter, the hemispherical lens 40 is formed by the method shown in FIG. After the light receiving element 50 is flip-chip mounted, the optical fiber 30 is mounted on the V-groove 15 or the like with an adhesive or the like to complete the process. At this time, the heat history at the time of mounting the light receiving element 50 needs to be set to be equal to or lower than the fixed temperature of the lens 40. For example, in the case of polyimide, since the curing temperature is about 300 ° C. to 400 ° C., it can be mounted with ordinary lead-tin eutectic solder or tin-Ag-based lead-free solder.
[0045]
As described above, according to the present embodiment, the optical module having the optical fiber 20 and the light receiving element 50 mounted on the substrate 10 and having good optical coupling therebetween can be realized. In this case, the light receiving element 50, the hemispherical lens 40, the reflecting mirror 30, and the optical fiber 20 can be positioned without adjustment, and the light coupling efficiency from the optical fiber 20 to the light receiving element is high, and the manufacturing can be performed at low cost. There is an effect that is. Further, since silicon is used as the substrate 10, it is possible to form electrodes in a wafer state, to form a reflecting mirror, a depression, a V-groove, and the like using a normal semiconductor process.
[0046]
Further, by configuring the reflecting mirror 30 with a dielectric multilayer film or the like, it is possible to add a polarization filter function and a wavelength filter function. Thereby, it is possible to receive only a specific wavelength, and it is also possible to apply to WDM applications. In the case where a large number of light receiving elements are required to cope with a large number of wavelengths as in the case of WDM, the effect of the present invention in which the lens alignment is not required is more prominent, and the cost is greatly reduced. The effect is exhibited.
[0047]
(Second embodiment)
FIG. 3 is a sectional view showing a schematic configuration of an optical module according to the second embodiment of the present invention. 1 and 2 are denoted by the same reference numerals, and detailed description thereof will be omitted.
[0048]
The shape of the substrate 10 and the arrangement positions of the reflecting mirror 30 and the hemispherical lens 40 are almost the same as in the first embodiment. However, the light receiving element 50 is not arranged on the uppermost surface 11 of the substrate 10. Further, the V-groove 15 is not formed on the bottom surface 12 of the concave portion of the substrate 10, and an end-emitting semiconductor laser 60 instead of the optical fiber 20 is bonded and fixed to this portion with solder or the like.
[0049]
With such a configuration, the laser beam from the edge-emitting semiconductor laser 60 installed on the substrate surface can be converted in optical path by the reflecting mirror 30 and taken out in the direction perpendicular to the substrate surface. 40 allows the light beam to be focused. As a result, it is possible to obtain a small surface light source with a lens with no adjustment and high relative position accuracy at low cost.
[0050]
In the above-described embodiment, the recess for lens positioning is formed by further digging the slope by etching, but a structure in which a bank is formed on the slope with metal or the like and the inside of the bank is equivalently recessed is also possible. It is.
[0051]
(Third embodiment)
FIG. 4 is a sectional view showing a schematic configuration of an optical module according to the third embodiment of the present invention. 1 and 2 are denoted by the same reference numerals, and detailed description thereof will be omitted.
[0052]
The depression 18 is inside a thick film metal provided on the periphery and a bank 18-1 formed by selective epitaxial growth. This makes it possible to form the inclined surface for the reflecting mirror by performing the anisotropic etching only once, so that the process can be controlled more easily than in the case where the inclined surface is formed by performing the etching multiple times. The effect of the roughened etching surface due to contaminants and the like mixed in the process and the cleaning process of the substrate can be reduced, and the quality of the reflector can be easily improved.
Such a configuration is realized as follows. The slope 13 is formed by anisotropically etching the silicon substrate 10 with KOH or the like using the oxide film or the nitride film as a mask. At this time, a surface having a low etching rate is selectively exposed on the slope 13. For example, by using a substrate whose main surface is 9.7 ° off from the (100) surface, the inclined (111) surface can be set at an angle of 45 ° with respect to the main surface.
[0053]
Subsequently, after a thermal oxide film or the like is formed on the entire surface, the oxide film at a position corresponding to the bank 18-1 is patterned, and silicon is grown epitaxially. At this time, since the regrowth section only needs to function as a bank, the growth surface accuracy and the like are not strictly required.
[0054]
Subsequently, after forming the V-groove 15 for mounting the optical fiber 20 in the same manner as the formation of the slope 13, the surface is formed with an insulating film such as an oxide film, and etching or lift-off using ordinary photolithography, Alternatively, a pad 16 for mounting a light receiving element, a solder bump, and the like are formed by plating. Subsequently, a reflecting mirror 30 of Au or the like is formed at a predetermined position on the slope by a lift-off method or the like. At this time, the formation of the pad 16 and the formation of the reflecting mirror 30 may be performed simultaneously.
[0055]
It is also possible to form the bank 18-1 with a thick metal instead of regrown silicon. In this case, after forming the electrodes and the reflecting mirror in the above-described procedure, similarly, a bank is formed in a desired position in a ring shape by plating or a lift-off method.
[0056]
Thereafter, the hemispherical lens 40 is formed by the method shown in FIG. After the light receiving element 50 is flip-chip mounted, the optical fiber 30 is mounted on the V-groove 15 or the like with an adhesive or the like to complete the process. At this time, the heat history at the time of mounting the light receiving element 50 needs to be set to be equal to or lower than the fixed temperature of the lens 40. For example, in the case of polyimide, since the curing temperature is about 300 ° C. to 400 ° C., it can be mounted with ordinary lead-tin eutectic solder or tin-Ag-based lead-free solder.
[0057]
As described above, according to the present embodiment, the optical module having the optical fiber 20 and the light receiving element 50 mounted on the substrate 10 and having good optical coupling therebetween can be realized. In this case, the light receiving element 50, the hemispherical lens 40, the reflecting mirror 30, and the optical fiber 20 can be positioned without adjustment, and the light coupling efficiency from the optical fiber 20 to the light receiving element is high, and the manufacturing can be performed at low cost. There is an effect that is. Further, since silicon is used as the substrate 10, it is possible to form electrodes in a wafer state, to form a reflecting mirror, a depression, a V-groove, and the like using a normal semiconductor process.
[0058]
(Modification)
Note that the present invention is not limited to the above embodiments. In the embodiment, the substrate material is silicon, but is not limited thereto. For example, when ceramic is used as the substrate material, the process becomes slightly complicated, and since the material is an insulator, there is no need to form an insulating film, and the dielectric constant can be freely changed, so that the electrode can be freely changed. Can be improved. In addition, when a glass substrate is used, the structure can be realized with other materials such as a low material cost.
[0059]
Further, in the configuration of FIG. 1, the optical semiconductor element is removed, and the present invention can be applied to a configuration in which only the optical fiber 20 is mounted on the substrate 10. Further, the optical transmission path is not necessarily limited to an optical fiber, but may be any configuration that can transmit light in a specific direction. For example, a thin film laminated waveguide may be formed on the second surface of the substrate.
[0060]
Further, the slope formed on the substrate is not necessarily limited to the 45-degree slope, and can be appropriately changed according to the specifications. Similarly, the curvature (radius) and the like of the hemispherical lens can be appropriately changed according to the specifications. In addition, various modifications can be made without departing from the scope of the present invention.
[0061]
【The invention's effect】
As described above in detail, according to the present invention, the optical semiconductor element, the lens, the reflecting mirror, and the optical transmission path can be positioned without adjustment, and the optical semiconductor element, the lens, the reflecting mirror, and the light transmission element can be positioned without any adjustment. The effect of high optical coupling efficiency and low-cost manufacturing is obtained.
[Brief description of the drawings]
FIG. 1 is a sectional view showing a schematic configuration of an optical module according to a first embodiment.
FIG. 2 is a sectional view showing a manufacturing process of the lens used in the first embodiment.
FIG. 3 is a sectional view showing a schematic configuration of an optical module according to a second embodiment.
FIG. 4 is a sectional view showing a schematic configuration of an optical module according to a third embodiment.
[Explanation of symbols]
10: substrate 11: uppermost surface of substrate (first surface)
12 Bottom of concave part (second surface)
13 Slope 15 V-groove 16 Pad 18 Depression 20 Optical fiber (optical transmission path)
Reference numeral 30: reflector 40, hemispherical lens 41, resin 42, mask 45, nozzle 50, light receiving element (optical semiconductor element)
51: light receiving surface 60: semiconductor laser (optical semiconductor element)

Claims (5)

A substrate having a step on the front side, and a slope formed on the step;
A hemispherical lens formed on a part of the slope,
A reflecting mirror formed on at least a part of the boundary between the bottom surface of the hemispherical lens and the slope,
An optical semiconductor device provided on a part of the substrate and irradiating light to the reflecting mirror from an oblique direction, or receiving reflected light from the reflecting mirror,
Comprising,
An optical module, wherein the slope has a depression, and at least a part of a bottom of the hemispherical lens is in the depression. A substrate having a step on the front side, and a slope formed on the step;
A hemispherical lens formed on a part of the slope,
A reflecting mirror formed on at least a part of the boundary between the bottom surface of the hemispherical lens and the slope,
An optical transmission path provided on a part of the substrate, wherein an optical path direction is defined in a direction parallel to the substrate surface, and the reflection mirror is disposed in an extending direction of the optical path,
Comprising,
An optical module, wherein the slope has a depression, and at least a part of a bottom of the hemispherical lens is in the depression. A first substrate having a slope between a first surface and a second surface that is lower than the first surface;
A hemispherical lens formed on a part of the slope,
A reflecting mirror formed on at least a part of the boundary between the bottom surface of the hemispherical lens and the slope,
An optical transmission path provided on the second surface of the first substrate, wherein an optical path direction is defined in a direction parallel to the substrate surface, and the reflection mirror is disposed in an extending direction of the optical path;
A second substrate flip-chip mounted on a first surface of the first substrate;
The light emitting direction or the incident direction is provided on the surface of the second substrate on the first substrate side, the light emitting direction or the incident direction is defined in a direction perpendicular to the substrate surface of the second substrate, and is oblique to the reflecting mirror. Irradiating light, or an optical semiconductor element to which reflected light from the reflecting mirror is incident,
Comprising,
By the conversion of the optical path by the reflecting mirror, the optical semiconductor element and the optical transmission path are optically coupled,
An optical module, wherein the slope has a depression, and at least a part of a bottom of the hemispherical lens is in the depression. The optical module according to any one of claims 1 to 3, wherein the reflectance of the reflecting mirror has wavelength dependency or polarization dependency. The optical module according to claim 1, wherein the substrate is made of silicon, and the slope is made of a (111) plane of the substrate.

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