Photoelectric conversion module

Abstract

The present invention provides a photoelectric conversion module that is advantageous in terms of reducing optical signal loss.　A photoelectric conversion module (1a) comprises a light-receiving element (10), a light-emitting element (20), a first light reflection surface (15), and a second light reflection surface (25). The first light reflection surface (15) reflects, toward the light-receiving element (10), light that has passed through the optical waveguide (5). The second light reflection surface (25) reflects, toward the optical waveguide (5), light that has been output from the light-emitting element (20). In the photoelectric conversion module (1a), a first angle θ1 and a second angle θ2 differ from each other.

Description

Optical-electrical conversion module

[0001] The present invention relates to an optical-electrical conversion module.

[0002] Conventionally, attempts have been made to convert electrical wiring into optical wiring.

[0003] For example, Patent Document 1 describes an optical wiring printed circuit board that transmits high-speed optical signals transmitted and received between chips or boards in equipment such as transmission devices. This optical wiring printed circuit board includes a substrate, an optical waveguide layer, and an optical element array. The optical waveguide layer is formed of a first cladding layer, a wiring core, and a second cladding layer. The wiring core is provided on the first cladding layer and is made of a material with a higher refractive index than the cladding layer. The second cladding layer is provided on the wiring core. The optical waveguide layer is provided with a mirror core pattern and a wiring core pattern. The mirror core pattern has a mirror portion that converts light input / output from the outside or an optical element into a different direction relative to the substrate surface. The wiring core pattern transmits light input to or output from the mirror portion. The mirror core pattern and the wiring core pattern are made of the same material that constitutes the wiring core layer. The mirror portion is provided on the side surface of the mirror core pattern so as to be tapered forward relative to the surface of the substrate, and has an inclined portion on the surface of the mirror portion where a metal film is provided.

[0004] It is explained that the angle θ of the inclined portion is preferably within a tolerance of ±2 degrees around 45 degrees relative to the substrate parallelism in order to maintain highly efficient optical coupling between the optical element and the mirror.

[0005] WO 2009 / 098834

[0006] From the viewpoints of responding to the increasing amount of information transmitted and reducing power consumption, optical-electrical conversion modules capable of converting optical signals to and from electrical signals are expected to play an important role in replacing electrical wiring with optical wiring. In such optical-electrical conversion modules, it is important to reduce the loss of optical signals.

[0007] In the optical wiring printed circuit board described in Patent Document 1, it is explained that the angle θ of the inclined portion of the mirror portion that converts light input / output from the outside or an optical element into a different direction relative to the board surface is preferably in the range of 45°±2°. However, the technology described in Patent Document 1 has room for reexamination from the perspective of reducing optical signal loss in an optoelectric conversion module.

[0008] Therefore, the present invention provides an optical-electrical conversion module that is advantageous from the viewpoint of reducing loss of optical signals.

[0009] the first angle is an acute angle formed by a first intersection line and a first straight line; the second angle is an acute angle formed by a second intersection line and a second straight line; the first intersection line is an intersection line between a first incident surface and the first light reflecting surface, with the first intersection line being an intersection point between an optical axis of the light receiving element and the first light reflecting surface; the first straight line is a line passing through the first intersection point on the first incident surface and perpendicular to the optical axis of the light receiving element; the second intersection line is an intersection line between a second incident surface and the second light reflecting surface, with the second intersection line being an intersection point between an optical axis of the light receiving element and the second light reflecting surface; the second straight line is a straight line that passes through the second intersection point on the second incident surface and is perpendicular to the optical axis of the light emitting element.

[0010] The above-described optical-electrical conversion module is advantageous in terms of reducing loss of optical signals.

[0011] Fig. 1 is a cross-sectional view schematically showing an example of an optical / electrical conversion module, and Fig. 2 is a cross-sectional view schematically showing another example of an optical / electrical conversion module.

[0012] Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the following description is for illustrative purposes only and the present invention is not limited to the following embodiments. In the accompanying drawings, the X-axis, Y-axis, and Z-axis are perpendicular to one another.

[0013] FIG. 1 is a cross-sectional view schematically illustrating an example of an opto-electrical conversion module. As shown in FIG. 1, the opto-electrical conversion module 1a includes a light-receiving element 10, a light-emitting element 20, a first light-reflecting surface 15, and a second light-reflecting surface 25. The first light-reflecting surface 15 reflects light that has passed through the optical waveguide 5 toward the light-receiving element 10. The second light-reflecting surface 25 reflects light emitted from the light-emitting element 20 toward the optical waveguide 5. In the opto-electrical conversion module 1a, the first angle θ1 and the second angle θ2 are different from each other. The first angle θ1 is an acute angle between the first intersection line C1 and the first straight line L1. The second angle θ2 is an acute angle between the second intersection line C2 and the second straight line L2. The first intersection line C1 is an intersection line between the first incident surface and the first light-reflecting surface 15, with the first intersection point P being the intersection point between the optical axis A1 of the light-receiving element 10 and the first light-reflecting surface 15. The first straight line L1 is a line that passes through the first intersection point P on the first incident surface and is perpendicular to the optical axis A1 of the light receiving element 10. The second intersection line C2 is an intersection line between the second incident surface and the second light reflecting surface 25, with the second intersection point Q, which is the intersection point between the optical axis A2 of the light emitting element 20 and the second light reflecting surface 25, as the incident point. The second straight line L2 is a line that passes through the second intersection point Q on the second incident surface and is perpendicular to the optical axis A2 of the light emitting element 20. For example, the optical axes A1 and A2 are parallel to the Z axis, and the first straight line L1 and the second straight line L2 are parallel to the X axis. The first incident surface and the second incident surface are, for example, planes parallel to the XZ plane.

[0014] The optoelectronic conversion module 1a receives an externally input electrical signal. The optoelectronic conversion module 1a includes, for example, a connector 3a for receiving the externally input electrical signal. The input electrical signal is converted into an optical signal, and the light-emitting element 20 emits light corresponding to the optical signal. The optical signal is transmitted through the optical waveguide 5. The light emitted from the light-emitting element 20 travels along the optical axis A2, is reflected by the second light-reflecting surface 25, and is guided to the optical waveguide 5. At this time, the reflected light travels along the direction of the second straight line L2 at a portion of the optical waveguide 5 that contacts the second light-reflecting surface 25. At a portion of the optical waveguide 5 that contacts the first light-reflecting surface 15, the light travels along the first straight line L1. The light that passes through the optical waveguide 5 is reflected by the first light-reflecting surface 15 and travels toward the light-receiving element 10. The reflected light travels along the optical axis A1, and is received by the light-receiving element 10. The optical signal transmitted in this manner is converted into an electrical signal, which is then output to the outside of the optical-electrical conversion module 1a. The optical-electrical conversion module 1a is provided with, for example, a connector 3b for outputting the electrical signal to the outside.

[0015] As described above, in the optoelectronic conversion module 1a, light traveling along the optical axis A2 is reflected by the second light-reflecting surface 25 so as to travel along the direction of the second straight line L2, and light traveling along the first straight line L1 is reflected by the first light-reflecting surface 15 so as to travel along the optical axis A1. Therefore, in order to reduce optical signal loss due to optical reflection, it seems advantageous to set both the first angle θ1 and the second angle θ2 to 45° as much as possible. For example, Patent Document 1 explains that the angle θ of the inclined portion of the mirror unit is preferably within a tolerance of ±2 degrees around 45° relative to the substrate parallelism. However, the inventors' studies have found that setting both the first angle θ1 and the second angle θ2 to 45° as much as possible is not optimal from the perspective of reducing optical signal loss due to optical reflection. To reduce optical loss during reflection to guide light emitted from a light-emitting element to an optical waveguide, it is important to consider factors specific to the light-emitting element. For example, the intensity distribution of light emitted from the light-emitting element may be due to the characteristics of the light-emitting element. In order to reduce the loss of light due to reflection to guide light passing through the optical waveguide to the light receiving element, it is important to consider the circumstances specific to the light receiving element. For example, the light receiving result of the light receiving element is affected by the intensity distribution of the light traveling toward the light receiving element. After extensive trial and error in light of these circumstances, the inventors have discovered that deliberately setting the first angle θ1 and the second angle θ2 to different angles is important for reducing the loss of optical signals in the opto-electrical conversion module. As described above, in the opto-electrical conversion module 1a, the first angle θ1 and the second angle θ2 are different from each other, which makes it easy to reduce the loss of optical signals.

[0016] For example, the first angle θ1 is equal to or greater than 42.0° and equal to or less than 45.0°, and the second angle θ2 is equal to or greater than 42.0° and equal to or less than 45.5°, in which case the loss of the optical signal in the optoelectric conversion module 1a is more likely to be reduced.

[0017] Preferably, the first angle θ1 is equal to or greater than 42.5° and equal to or less than 44.5°, and the second angle θ2 is equal to or greater than 43.0° and equal to or less than 45.5°.

[0018] More preferably, the first angle θ1 is equal to or greater than 43.5° and equal to or less than 44.5°, and the second angle θ2 is equal to or greater than 43.0° and equal to or less than 45.0°.

[0019] More preferably, the first angle θ1 is equal to or greater than 43.5° and equal to or less than 44.5°, and the second angle θ2 is equal to or greater than 44.0° and equal to or less than 45.0°. Particularly preferably, the first angle θ1 is greater than 43.5° and less than 44.5°, and the second angle θ2 is greater than 44.0° and equal to or less than 45.0°. Alternatively, the first angle θ1 may be greater than 43.5° and equal to or less than 44.0°, and the second angle θ2 may be greater than 44.0° and less than 45.0°.

[0020] As long as the first angle θ1 and the second angle θ2 are different from each other, the sum of the first angle θ1 and the second angle θ2 is not limited to a specific value. The sum (θ1 + θ2) is, for example, equal to or greater than 84.5° and less than 90°. In this case, optical signal loss in the optical-electrical conversion module 1a is more likely to be reduced.

[0021] Preferably, the sum (θ1+θ2) is equal to or greater than 86.5° and equal to or less than 89.5°, and more preferably, the sum (θ1+θ2) is equal to or greater than 87.5° and equal to or less than 89.0°.

[0022] As long as the first angle θ1 and the second angle θ2 are different from each other, the magnitude relationship between them is not limited to a specific relationship. For example, the first angle θ1 and the second angle θ2 satisfy the following condition (Ia) or (Ib). In this case, the optical signal loss in the optoelectric conversion module 1a is more likely to be reduced. (Ia) The second angle θ2 is less than 44.5°, and the first angle θ1 is greater than the second angle θ2. (Ib) The second angle θ2 is 44.5° or greater, and the first angle θ1 is smaller than the second angle θ2.

[0023] Preferably, the first angle θ1 and the second angle θ2 satisfy the above condition (Ia), and the first angle θ1 is 44.5° or less.

[0024] Preferably, the first angle θ1 and the second angle θ2 satisfy the above condition (Ib), and the first angle θ1 is 42.0° or greater.

[0025] Preferably, the first angle θ1 and the second angle θ2 satisfy the above condition (Ib), and the second angle θ1 is 45.5° or less.

[0026] More preferably, the first angle θ1 and the second angle θ2 satisfy the above condition (Ib), and the second angle θ2 is less than 45.0°.

[0027] As long as the first angle θ1 and the second angle θ2 are different from each other, the difference |θ1-θ2| between the first angle θ1 and the second angle θ2 is not limited to a specific value. The difference |θ1-θ2| is, for example, 1.5° or less. In this case, optical signal loss in the optical-electrical conversion module 1a is more likely to be reduced. Because the first angle θ1 and the second angle θ2 are different from each other, the difference |θ1-θ2| is greater than 0°.

[0028] The difference |θ1−θ2| is preferably 1.0° or less, and more preferably 0.5° or less.

[0029] The light receiving element 10 is, for example, a photodiode (PD), and the light emitting element 20 is, for example, a vertical cavity surface emitting laser (VCSEL).

[0030] 1, in the optoelectric conversion module 1a, the optical waveguide 5 includes, for example, a first optical waveguide 5a, a second optical waveguide 5b, and a third optical waveguide 5c. The first light reflecting surface 15 is formed, for example, as one end face in the X-axis direction of the first optical waveguide 5a. The second light reflecting surface 25 is formed, for example, as one end face in the X-axis direction of the second optical waveguide 5b.

[0031] The optical waveguide 5 includes, for example, an optical fiber 2. The optical fiber 2 forms, for example, a third optical waveguide 5c. One end of the optical fiber 2 is connected to the first optical waveguide 5a, and the other end of the optical fiber 2 is connected to the second optical waveguide 5b. The optoelectric conversion module 1a includes, for example, a connector 3c and a connector 3d. The second optical waveguide 5b and the optical fiber 2 are connected by the connector 3c. The first optical waveguide 5a and the optical fiber 2 are connected by the connector 3d.

[0032] The optical fiber 2 includes, for example, a core 2a and a clad 2b, and is, for example, a plastic optical fiber (POF).

[0033] 1 , the optical-electrical conversion module 1a includes, for example, a first cladding layer 31, a second cladding layer 32, and a first core 33. The first core 33 is disposed between the first cladding layer 31 and the second cladding layer 32. The refractive index of the first core 33 is higher than the refractive index of the first cladding layer 31 and the refractive index of the second cladding layer 32. The first optical waveguide 5a is formed by a laminate including the first cladding layer 31, the second cladding layer 32, and the first core 33. Each of the first cladding layer 31, the second cladding layer 32, and the first core 33 contains, for example, a predetermined photosensitive resin.

[0034] The optical-electrical conversion module 1a includes, for example, a first metal layer 35. The first metal layer 35 is disposed in contact with the first clad layer 31. The first metal layer 35 has a through hole 35h, which is filled with the first clad layer 31. The first metal layer 35 includes, for example, stainless steel and an alloy such as 42 alloy. The optical axis A1 extends through the through hole 35h. The first metal layer 35 and the first clad layer 31 are disposed to form a flat surface on the opposite side of the first core 33 in their thickness direction.

[0035] The optical-electrical conversion module 1a includes, for example, a first insulating layer 51, a first electrical wiring 52, and a first coverlay 53. The first insulating layer 51 is disposed on the flat surface formed by the first metal layer 35 and the first clad layer 31. The first insulating layer 51 contains, for example, a light-transmitting resin such as photosensitive polyimide. The first electrical wiring 52 is disposed on the first insulating layer 51 and is electrical wiring for transmitting electrical signals generated by light reception in the light-receiving element 10 or for necessary grounding. The first coverlay 53 is disposed on the first insulating layer 51 or the first electrical wiring 52. The first coverlay 53 has electrical insulating properties and light-transmitting properties and contains, for example, a resin such as photosensitive polyimide.

[0036] The photoelectric conversion module 1a includes, for example, an IC chip 12. The IC chip 12 amplifies, for example, an electrical signal generated by receiving light in the light receiving element 10. The amplified electrical signal is output to the outside of the photoelectric conversion module 1a.

[0037] The light-receiving element 10 and the IC chip 12 are mounted on a laminate including, for example, a first insulating layer 51, a first electrical wiring 52, and a first coverlay 53. The first electrical wiring 52 includes a portion that is not covered by the first coverlay 53, and this portion electrically connects the light-receiving element 10 and the IC chip 12 to the first electrical wiring 52.

[0038] 1 , the optical-electrical conversion module 1a includes, for example, a third cladding layer 41, a fourth cladding layer 42, and a second core 43. The second core 43 is disposed between the third cladding layer 41 and the fourth cladding layer 42. The refractive index of the second core 43 is higher than the refractive index of the third cladding layer 41 and the refractive index of the fourth cladding layer 42. The second optical waveguide 5b is formed by a laminate including the third cladding layer 41, the fourth cladding layer 42, and the second core 43. Each of the first cladding layer 41, the second cladding layer 42, and the second core 43 contains, for example, a predetermined photosensitive resin.

[0039] The optical-electrical conversion module 1a includes, for example, a second metal layer 45. The second metal layer 45 is disposed in contact with the third clad layer 41. The second metal layer 45 has a through hole 45h, which is filled with the third clad layer 41. The second metal layer 45 includes, for example, stainless steel and an alloy such as 42 alloy. The optical axis A2 extends into the through hole 45h. The second metal layer 45 and the third clad layer 41 are disposed to form a flat surface on the opposite side of the second core 43 in their thickness direction.

[0040] The photoelectric conversion module 1a includes, for example, a second insulating layer 61, a second electrical wiring 62, and a second coverlay 63. The second insulating layer 61 is disposed on the flat surface formed by the second metal layer 45 and the third cladding layer 41. The second insulating layer 61 contains, for example, a light-transmitting resin such as photosensitive polyimide. The second electrical wiring 62 is disposed on the second insulating layer 61 and is electrical wiring for transmitting an electrical signal to cause the light-emitting element 20 to emit light or for necessary grounding. The second coverlay 63 is disposed on the second insulating layer 61 or the second electrical wiring 62. The second coverlay 63 has electrical insulating properties and light-transmitting properties and contains, for example, a resin such as photosensitive polyimide.

[0041] The photoelectric conversion module 1a includes, for example, an IC chip 22. The IC chip 22 is, for example, a driver IC for the light emitting element 20, and controls the light emission of the light emitting element 20.

[0042] The light emitting element 20 and the IC chip 22 are mounted on a laminate including, for example, a second insulating layer 61, a second electrical wiring 62, and a second coverlay 63. The second electrical wiring 62 includes a portion that is not covered with the second coverlay 63, and this portion electrically connects the light emitting element 20 and the IC chip 22 to the second electrical wiring 62.

[0043] An example of a manufacturing method for the photoelectric conversion module 1a will be described. An insulating photosensitive resin is applied to a metal substrate, which is the material for the first metal layer 35, and a first insulating layer 51 having a predetermined pattern is formed by photolithography. Next, a first electrical wiring 52 is formed using a wiring formation method such as a semi-additive method or a subtractive method. Next, an insulating photosensitive resin is applied to the first insulating layer 51 and the first electrical wiring 52, and portions of the first electrical wiring 52 necessary for electrical connection are exposed by photolithography. In this manner, a first coverlay 53 is formed. Next, through-holes 35h are formed in the metal substrate by etching. Next, a photosensitive resin, which is the material for the first cladding layer 31, is applied to the side of the metal substrate opposite the first insulating layer 51 to form a coating. This coating is cured by light irradiation to form the first cladding layer 31. Next, a first core 33 is formed in a predetermined pattern by photolithography. Next, a photosensitive resin, which is the material of the second cladding layer 32, is applied so as to cover the first cladding layer 31 and the first core 33, to form a coating film. The coating film is cured by light irradiation to form the second cladding layer 32. As a result, a laminate including the first cladding layer 31, the second cladding layer 32, and the first core 33 is obtained. Laser processing is performed on this laminate to form the first light reflecting surface 15. A laser such as an excimer laser is used for the laser processing. In the laser processing, the laser light source is moved in a planar direction perpendicular to the thickness direction of the laminate. The laser output and the amount of movement of the laser in the planar direction in the laser processing are adjusted so that the first angle θ1 is within a predetermined range.

[0044] An insulating photosensitive resin is applied to a metal substrate, which is the material for the second metal layer 45, and a second insulating layer 61 having a predetermined pattern is formed by photolithography. Next, a second electrical wiring 62 is formed using a wiring formation method such as a semi-additive method or a subtractive method. Next, an insulating photosensitive resin is applied to the second insulating layer 61 and the second electrical wiring 62, and the portion of the second electrical wiring 62 necessary for electrical connection is exposed by photolithography. In this manner, a second coverlay 63 is formed. Next, through-holes 45h are formed in the metal substrate by etching. Next, a photosensitive resin, which is the material for the third clad layer 41, is applied to the side of the metal substrate opposite the second insulating layer 61 to form a coating. This coating is cured by light irradiation to form the fourth clad layer 41. Next, a second core 43 is formed in a predetermined pattern by photolithography. Next, a photosensitive resin, which is the material for the second clad layer 32, is applied to cover the third clad layer 41 and the second core 43 to form a coating. This coating film is cured by light irradiation to form the fourth cladding layer 42. This results in a laminate including the third cladding layer 41, the fourth cladding layer 42, and the second core 43. This laminate is laser processed to form the second light reflecting surface 25. A laser such as an excimer laser is used for the laser processing. In the laser processing, the laser light source is moved in a planar direction perpendicular to the thickness direction of the laminate. The laser output and the amount of movement of the laser in the planar direction in the laser processing are adjusted so that the second angle θ2 falls within a predetermined range.

[0045] Next, the light-receiving element 10 and the IC chip 12 are mounted on the exposed portion of the first electrical wiring 52. In addition, the light-emitting element 20 and the IC chip 22 are mounted on the exposed portion of the second electrical wiring 62. Furthermore, the connectors 3a, 3b, 3c, and 3d are attached. Next, one end of the optical fiber 2 is attached to the connector 3d, and the other end of the optical fiber 2 is attached to the connector 3c. For example, an optical-electrical conversion module 1a can be obtained in this manner.

[0046] The optical-electrical conversion module 1a can be modified in various respects. For example, the optical-electrical conversion module 1a may be modified to become the optical-electrical conversion module 1b shown in FIG. 2. The optical-electrical conversion module 1b has the same configuration as the optical-electrical conversion module 1a, except for parts that will be particularly described. The components of the optical-electrical conversion module 1b that are the same as or correspond to the components of the optical-electrical conversion module 1a are designated by the same reference numerals, and detailed description thereof will be omitted. The description of the optical-electrical conversion module 1a also applies to the optical-electrical conversion module 1b, unless technically inconsistent.

[0047] As shown in FIG. 2, in the opto-electrical conversion module 1b, the light receiving element 10, the light emitting element 20, the first light reflecting surface 15, the second light reflecting surface 25, and the optical waveguide 5 are arranged on a common opto-electrical hybrid substrate.

[0048] In the optoelectric conversion module 1b, the optical waveguide 5 does not include an optical fiber, and a first light reflecting surface 15 is formed at one end of a laminate including a first cladding layer 31, a second cladding layer 32, and a first core 33. In addition, a second light reflecting surface 25 is formed at the other end of the laminate.

[0049] The present invention will be described in more detail below with reference to examples. However, the present invention is not limited to the following examples. First, the evaluation methods used in the examples will be described.

[0050] Samples of photoelectric conversion modules were produced according to the above-described method for producing the photoelectric conversion module 1a. In producing each sample, core materials corresponding to the first core 31 and the second core 33 of the photoelectric conversion module 1a were prepared by mixing the following components in the following amounts: 30 parts by mass of trifunctional epoxy resin (VG-3101L, manufactured by Printec Co., Ltd.), 30 parts by mass of bifunctional epoxy resin A (JER-1002, manufactured by Mitsubishi Chemical Corporation), 20 parts by mass of bifunctional epoxy resin B (Oxol PG100, manufactured by Osaka Gas Chemicals Co., Ltd.), 50 parts by mass of rubber-modified epoxy resin (YX-7180H40, manufactured by Mitsubishi Chemical Corporation), 2 parts by mass of photoacid generator (CPI-101A, manufactured by San-Apro Co., Ltd.), and 23 parts by mass of ethyl lactate (solvent, manufactured by Resonac Co., Ltd.).

[0051] In producing each sample, materials for the portions corresponding to the first cladding layer 31, the second cladding layer 32, the third cladding layer 41, and the fourth cladding layer 42 of the photoelectric conversion module 1a were prepared by mixing the following components in the following amounts: 20 parts by mass of trifunctional epoxy resin (VG-3101L manufactured by Printec), 30 parts by mass of bifunctional epoxy resin A (JER-1002 manufactured by Mitsubishi Chemical Corporation), 30 parts by mass of bifunctional epoxy resin B (Oxol PG100 manufactured by Osaka Gas Chemicals Co., Ltd.), 30 parts by mass of multifunctional epoxy resin (EHPE-3150 manufactured by Daicel Corporation), 2 parts by mass of photoacid generator (CPI-101A manufactured by San-Apro Co., Ltd.), and 23 parts by mass of ethyl lactate (solvent manufactured by Resonac Corporation).

[0052] In producing each sample, a laminate corresponding to a laminate including the first cladding layer 31, the second cladding layer 32, and the first core 33, formed using the above materials, was subjected to laser processing to form a light-receiving-side light-reflecting surface having a first angle θ1. A laminate corresponding to a laminate including the third cladding layer 41, the fourth cladding layer 42, and the second core 43, formed using the above materials, was subjected to laser processing to form a light-emitting-side light-reflecting surface having a second angle θ2. The first angle θ1 and the second angle θ2 for each sample are shown in Table 1. The magnitudes of the first angle θ1 and the second angle θ2 were adjusted by adjusting the laser output and the amount of movement of the laser in the planar direction during laser processing of these laminates.

[0053] The magnitudes of the first angle θ1 and the second angle θ2 were measured using an inspection device (optical tester) manufactured by Synergy Opto. In this measurement, the focus of a microscope mounted on the optical tester was moved relative to the sample, and position information (height and planar position) was obtained at the point where the focus matched. Next, the position information was used to calculate the mirror angles (i.e., the magnitudes of the first angle θ1 and the second angle θ2).

[0054] In fabricating each sample, a photodiode manufactured by Coherent was used as an element corresponding to the light receiving element 10, and a VCSEL manufactured by Coherent was used as an element corresponding to the light emitting element 20.

[0055] <Evaluation of optical loss on the light-emitting side> In each sample, the connector corresponding to connector 3a was connected to a DC power supply and an AC signal source, and the VCSEL was made to emit light. In this state, an optical power meter manufactured by ADC was placed as close as possible to the connector corresponding to connector 3c, and the output M 3C Separately, the original output N V The light loss on the light-emitting side, L, was measured based on the following formula (1): E The optical loss L [dB] was determined. The results are shown in Table 1. E [dB]=-10×log(M 3C / N V ) Formula (1)

[0056] <Evaluation of optical loss on the light-emitting side> In each sample, a pair of connectors corresponding to connectors 3c and 3d were connected to each other, the connector corresponding to connector 3a was connected to a power supply, and the connector corresponding to connector 3b was connected to a power supply. In addition, the current output terminal of the photodiode was connected to a digital multimeter manufactured by Texio Technology. In this state, the VCSEL was made to emit light, and the current output J of the photodiode was measured. P The optical loss L on the light receiving side was measured based on the following formula (2): R The optical loss L [dB] was determined. The results are shown in Table 1. In equation (2), α is the photoelectric conversion coefficient of the photodiode, which is 0.6. The results are shown in Table 1. R [dB]=-10×log(J P ×α / M 3C ) Formula (2)

[0057] As shown in Table 1, when the first angle θ1 and the second angle θ2 are different from each other, the light loss L is smaller than when the first angle θ1 and the second angle θ2 are both 45.0°. E and optical loss L R This suggests that the sum of the two becomes smaller, and the loss of the optical signal can be reduced.

[0058]

[0059] (Discussion) As shown in Samples No. 1 to 14, the light loss LE and optical loss L R The sum of (L in Table 1) E +L R It was found that the optical loss L (corresponding to 4.47 dB or less) was relatively low (for example, 4.47 dB or less). This shows that it is important for the first angle θ1 and the second angle θ2 to have different values ​​in order to reduce the loss of the optical signal in the optical-electrical conversion module. Furthermore, as shown in Sample No. 16, even if the values ​​of θ1 and θ2 are both 45°, which is considered by those skilled in the art to be appropriate angles from the viewpoint of light reflection, the optical loss L E and optical loss L R Therefore, even if the values ​​of the first angle θ1 and the second angle θ2 are both set to 45°, the optical loss L E and optical loss L R Furthermore, when the values ​​of the first angle θ1 and the second angle θ2 both exceed 45° (Sample No. 17) or are 42° or less (Sample No. 18), the light loss L E and optical loss L R The sum of these values ​​exceeded 5.0 dB. The inventors believe that this is because light is not being reflected appropriately from each light-reflecting surface.

[0060] a first light reflecting surface that reflects light that has passed through a light waveguide toward the light receiving element; and a second light reflecting surface that reflects light emitted from the light emitting element toward the light waveguide, wherein a first angle and a second angle are different from each other, the first angle is an acute angle formed by a first intersection line and a first straight line, the second angle is an acute angle formed by a second intersection line and a second straight line, the first intersection line is an intersection line between a first incident surface and the first light reflecting surface, with the first intersection line being an incident point at a first intersection point where an optical axis of the light receiving element intersects with the first light reflecting surface, the first straight line is a straight line that passes through the first intersection point on the first incident surface and is perpendicular to the optical axis of the light receiving element, and the second intersection line is an intersection line between a second incident surface and the second light reflecting surface, with the second intersection line being an incident point at a second intersection point where an optical axis of the light emitting element intersects with the second light reflecting surface, the second straight line is a straight line that passes through the second intersection point on the second incident surface and is perpendicular to the optical axis of the light emitting element.

[0061] A second aspect of the present invention provides the photoelectric conversion module of the first aspect, wherein the first angle is equal to or greater than 42.0° and equal to or less than 45.0°, and the second angle is equal to or greater than 42.0° and equal to or less than 45.5°.

[0062] A third aspect of the present invention provides the photoelectric conversion module of the second aspect, wherein the first angle is equal to or greater than 42.5° and equal to or less than 44.5°, and the second angle is equal to or greater than 43.0° and equal to or less than 45.5°.

[0063] A fourth aspect of the present invention provides the photoelectric conversion module of the second aspect, wherein the first angle is equal to or greater than 43.5° and equal to or less than 44.5°, and the second angle is equal to or greater than 43.0° and equal to or less than 45.0°.

[0064] A fifth aspect of the present invention provides the photoelectric conversion module of the second aspect, wherein the first angle is equal to or greater than 43.5° and equal to or less than 44.5°, and the second angle is equal to or greater than 44.0° and equal to or less than 45.0°.

[0065] A sixth aspect of the present invention provides the photoelectric conversion module according to any one of the second to fifth aspects, wherein the sum of the first angle and the second angle is equal to or greater than 84.5° and less than 90°.

[0066] A seventh aspect of the present invention provides the photoelectric conversion module of the sixth aspect, wherein the sum is equal to or greater than 86.5° and equal to or less than 89.5°.

[0067] An eighth aspect of the present invention provides the photoelectric conversion module of the sixth aspect, wherein the sum is equal to or greater than 87.5° and equal to or less than 89.0°.

[0068] A ninth aspect of the present invention provides an optoelectric conversion module according to any one of the second to eighth aspects, wherein the first angle and the second angle satisfy the following condition (Ia) or (Ib): (Ia) the second angle is less than 44.5° and the first angle is greater than the second angle; or (Ib) the second angle is 44.5° or greater and the first angle is smaller than the second angle.

[0069] A tenth aspect of the present invention provides the photoelectric conversion module of the ninth aspect, wherein the first angle and the second angle satisfy the condition (Ia) above, and the first angle is 44.5° or less.

[0070] An eleventh aspect of the present invention provides the photoelectric conversion module of the ninth aspect, wherein the first angle and the second angle satisfy the condition (Ib) above, and the first angle is 42.0° or greater.

[0071] A twelfth aspect of the present invention provides the photoelectric conversion module of the ninth aspect, wherein the first angle and the second angle satisfy the condition (Ib) above, and the second angle is 45.5° or less.

[0072] A thirteenth aspect of the present invention provides the photoelectric conversion module of the ninth aspect, wherein the first angle and the second angle satisfy the condition (Ib) above, and the second angle is less than 45.0°.

[0073] A fourteenth aspect of the present invention provides the photoelectric conversion module of any one of the first to thirteenth aspects, wherein a difference between the first angle and the second angle is 1.5° or less.

[0074] A fifteenth aspect of the present invention provides the photoelectric conversion module according to any one of the first to thirteenth aspects, wherein the difference between the first angle and the second angle is 1.0° or less.

[0075] A sixteenth aspect of the present invention provides the photoelectric conversion module according to any one of the first to thirteenth aspects, wherein the difference between the first angle and the second angle is 0.5° or less.

[0076] A seventeenth aspect of the present invention provides an optical-electrical conversion module according to any one of the first to sixteenth aspects, further comprising an optical fiber having one end and the other end, the optical waveguide including a first optical waveguide and a second optical waveguide, the one end of the optical fiber being connected to the first optical waveguide, and the other end of the optical fiber being connected to the second optical waveguide.

[0077] An eighteenth aspect of the present invention provides an opto-electrical conversion module according to any one of the first to sixteenth aspects, wherein the light receiving element, the light emitting element, the first light reflecting surface, the second light reflecting surface, and the optical waveguide are arranged on a common opto-electrical hybrid substrate.

Claims

1. A light receiving element, a light emitting element, a first light reflecting surface that reflects light that has passed through an optical waveguide toward the light receiving element, and a second light reflecting surface that reflects light emitted from the light emitting element toward the optical waveguide, wherein a first angle and a second angle are different from each other, the first angle is an acute angle formed by a first intersection line and a first straight line, the second angle is an acute angle formed by a second intersection line and a second straight line, the first intersection line is an intersection line between a first incident surface and the first light reflecting surface, with the first intersection point being an intersection point between the optical axis of the light receiving element and the first light reflecting surface as the incident point, the first straight line is a straight line that passes through the first intersection point on the first incident surface and is perpendicular to the optical axis of the light receiving element, and the second intersection line is an intersection line between a second incident surface and the second light reflecting surface, with the second intersection point being an intersection point between the optical axis of the light emitting element and the second light reflecting surface as the incident point, the second straight line is a straight line that passes through the second intersection point on the second incident surface and is perpendicular to the optical axis of the light-emitting element.

2. The optical-electrical conversion module according to claim 1, wherein the first angle is equal to or greater than 42.0° and equal to or less than 45.0°, and the second angle is equal to or greater than 42.0° and equal to or less than 45.5°.

3. The optical-electrical conversion module according to claim 2, wherein the first angle is equal to or greater than 42.5° and equal to or less than 44.5°, and the second angle is equal to or greater than 43.0° and equal to or less than 45.5°.

4. The optical-electrical conversion module according to claim 2, wherein the first angle is equal to or greater than 43.5° and equal to or less than 44.5°, and the second angle is equal to or greater than 43.0° and equal to or less than 45.0°.

5. The optical-electrical conversion module according to claim 2, wherein the first angle is equal to or greater than 43.5° and equal to or less than 44.5°, and the second angle is equal to or greater than 44.0° and equal to or less than 45.0°.

6. The optical-electrical conversion module according to claim 2, wherein the sum of the first angle and the second angle is equal to or greater than 84.5° and less than 90°.

7. The optical-electrical conversion module according to claim 6, wherein the sum is equal to or greater than 86.5° and equal to or less than 89.5°.

8. The optical-electrical conversion module according to claim 6, wherein the sum is equal to or greater than 87.5° and equal to or less than 89.0°.

9. The optical-electrical conversion module according to claim 2, wherein the first angle and the second angle satisfy the following condition (Ia) or (Ib): (Ia) the second angle is less than 44.5° and the first angle is greater than the second angle, or (Ib) the second angle is 44.5° or greater and the first angle is smaller than the second angle.

10. The optical-electrical conversion module according to claim 9, wherein the first angle and the second angle satisfy the condition (Ia), and the first angle is 44.5° or less.

11. The optical-electrical conversion module according to claim 9, wherein the first angle and the second angle satisfy the condition (Ib), and the first angle is 42.0° or greater.

12. The optical-electrical conversion module according to claim 9, wherein the first angle and the second angle satisfy the condition (Ib), and the second angle is 45.5° or less.

13. The optical-electrical conversion module according to claim 9, wherein the first angle and the second angle satisfy the condition (Ib), and the second angle is less than 45.0°.

14. The optical-electrical conversion module according to claim 1, wherein the difference between the first angle and the second angle is 1.5° or less.

15. The optical-electrical conversion module according to claim 1, wherein the difference between the first angle and the second angle is 1.0° or less.

16. The optical-electrical conversion module according to claim 1, wherein the difference between the first angle and the second angle is 0.5° or less.

17. The optical-electrical conversion module according to claim 1, further comprising an optical fiber having one end and the other end, wherein the optical waveguide includes a first optical waveguide and a second optical waveguide, wherein the one end of the optical fiber is connected to the first optical waveguide, and the other end of the optical fiber is connected to the second optical waveguide.

18. The optoelectronic conversion module according to claim 1, wherein the light receiving element, the light emitting element, the first light reflecting surface, the second light reflecting surface, and the optical waveguide are arranged on a common optoelectronic hybrid substrate.

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