JP7852307B2 - Waveguide substrate, optical module, and method for manufacturing the optical module - Google Patents

Description

This invention relates to waveguide substrates and the like.

In recent years, optical communication has become increasingly popular in information processing equipment to achieve higher capacity and higher speeds. Various optical modules have been developed for this purpose. One type of optical module utilizes a wiring board equipped with optical waveguides (hereinafter referred to as a waveguide substrate). In optical modules using waveguide substrates, precise alignment of the waveguides and optical elements is necessary. Recently, with the miniaturization and high integration of optical modules, the demands for alignment accuracy have become stricter. Furthermore, waveguide substrates have dimensional variations due to the manufacturing process. Therefore, it is necessary to correct for these dimensional variations and accurately align the optical elements to the waveguide substrate.

A technique for accurately aligning a waveguide with an optical element is disclosed, for example, in Patent Document 1. The optical element device in Patent Document 1 uses a substantially sheet-shaped optical waveguide extending in the longitudinal direction. The optical waveguide comprises an undercladding, a core and a dummy core, and an overcladding, arranged sequentially toward the other side in the thickness direction. Multiple cores are arranged, and they are spaced apart from each other in the width direction. Each core has a mirror for an optical path conversion member on one end face in the longitudinal direction. Dummy cores are provided parallel to the cores on the other side in the thickness direction of the undercladding. The dummy cores are positioned on both outer sides in the width direction of the core. The dummy cores have a dummy mirror serving as an alignment mark on one end face in the longitudinal direction. The dummy mirrors are positioned on both outer sides in the width direction of the mirror on the core.

When aligning an optical element to a waveguide substrate, inspection light is input from the other end of the dummy core in the longitudinal direction, and the inspection light is emitted from the alignment mark (dummy mirror) in one direction in the thickness direction. While recognizing this inspection light with a camera, the irradiation opening of the optical element is aligned with the mirror and positioned accordingly. Patent Document 1 states that this configuration suppresses a decrease in the positional accuracy of the optical element relative to the mirror.

Related technology is also disclosed in Patent Document 2.

Japanese Patent Publication No. 2020-016757 Japanese Patent Publication No. 2007-017559

The technology described in Patent Document 1 had the problem of requiring a wide waveguide substrate. This is because the dummy core and dummy mirror are provided on both the outer sides in the width direction of the communication core and mirror.

This invention has been made in view of the above-mentioned problems, and aims to provide a waveguide substrate, etc., that suppresses a decrease in the accuracy of alignment of optical elements to the waveguide substrate without increasing the width of the waveguide substrate.

To solve the above problems, the waveguide substrate of the present invention comprises a sheet-like cladding, a core surrounded by the cladding and extending in a first direction, a first region provided on one end of the cladding in the first direction for mounting a first optical element, a second region provided on the other end of the cladding in the first direction for mounting a second optical element, a first mirror that reflects light propagating through the core between the first and second regions in the first region in a direction perpendicular to the first main surface of the cladding, and on one end of the first mirror in the first direction It comprises a second mirror, positioned adjacent to the first region, which reflects light propagating from the core within the first region along one end of the first mirror in the first direction in a direction perpendicular to the first main surface of the cladding within the first region; and a third mirror, which reflects light incident on the cladding from between one end of the first region of the first main surface in the first direction and one end of the cladding in the first direction, towards the second mirror within the core.

Furthermore, the optical module of the present invention comprises the waveguide substrate described above, the first optical element aligned with the first mirror and mounted in the first region, and the second optical element aligned with the fourth mirror and mounted in the second region.

Furthermore, the present invention relates to a method for manufacturing an optical module, wherein the optical module is manufactured by mounting an optical element on a waveguide substrate, and the waveguide substrate comprises a sheet-like cladding, a core surrounded by the cladding and extending in a first direction, a first region provided on one end of the cladding in the first direction for mounting a first optical element, a second region provided on the other end of the cladding in the first direction for mounting a second optical element, a first mirror that reflects light propagated through the core between the first and second regions in the first region in a direction perpendicular to the first main surface of the cladding, and a third element arranged adjacent to one end of the first mirror in the first direction. The device comprises a second mirror that reflects light propagating from the core within the first region along one end of the first mirror in the first direction in a direction perpendicular to the first main surface of the cladding within the first region, and a third mirror that reflects light incident on the cladding from between one end of the first region of the first main surface in the first direction and one end of the cladding in the first direction towards the second mirror within the core. Alignment light, which is light for aligning the first optical element, is incident on the third mirror from the first main surface, and the first optical element is aligned to the first region based on the position of the alignment light emitted from the second mirror.

The effect of the present invention is to provide a waveguide substrate, etc., that suppresses a decrease in the accuracy of alignment of optical elements to the waveguide substrate without increasing the width of the waveguide substrate.

This is a schematic plan view showing a waveguide substrate of the first embodiment. This is a schematic cross-sectional view showing a waveguide substrate of the first embodiment. This is a schematic cross-sectional view of the waveguide substrate of the first embodiment at a different location. This is a schematic cross-sectional view showing a modified example of the waveguide substrate of the first embodiment. This is a schematic cross-sectional view showing an example of a manufacturing method for an optical module according to the first embodiment. This is a schematic cross-sectional diagram showing the relationship between the alignment light and the signal light in the first embodiment. This is a schematic cross-sectional view showing an optical module of the first embodiment. This is a schematic cross-sectional view showing a first modified example of the optical module of the first embodiment. This is a schematic cross-sectional view showing a second modified example of the optical module of the first embodiment. This is a schematic cross-sectional view showing the first state of a third modified example of the optical module of the first embodiment. This is a schematic cross-sectional view showing the second state of a third modified example of the waveguide substrate of the first embodiment. This is a schematic cross-sectional view showing a waveguide substrate of the second embodiment.

The embodiments of the present invention will be described in detail below with reference to the drawings. However, while the embodiments described below include technically preferred limitations for carrying out the present invention, they do not limit the scope of the invention. Similar components in each drawing are given the same number, and their descriptions may be omitted.

(First embodiment)
Figure 1 is a schematic plan view showing the waveguide substrate 10 of the first embodiment. Figure 2 is a schematic cross-sectional view showing the waveguide substrate of the first embodiment. Figure 2 is a schematic cross-sectional view at line A-A' in Figure 1. Figure 3 is a schematic cross-sectional view of the waveguide substrate of the first embodiment at a different location. Figure 2 is a schematic cross-sectional view at line B-B' in Figure 1.

The waveguide substrate 10 comprises a cladding 1, a core 2, a first mirror 3, a second mirror 4, a third mirror 5, a fourth mirror 6, a fifth mirror 7, and a sixth mirror 8. The cladding 1 is also provided with a first region 1a and a second region 1b.

The cladding 1 is sheet-like. The core 2 is surrounded by the cladding. The core 2 extends in a first direction. Similar to well-known waveguides that guide light, the core 2 is the path for light, and the cladding 1 is the layer that confines the light within the core 2. The refractive index of the core 2 is higher than that of the cladding 1. Therefore, when light enters the core 2, it undergoes total internal reflection at the boundary between the core 2 and the cladding 1, and propagates in the direction of the core 2's extension (the first direction). The waveguide substrate 10 is typically shaped such that the first direction (the direction of light transmission) is longer, and the width direction (perpendicular to the first direction) is shorter. In other words, the waveguide substrate 10 is generally shaped such that it is longer in the left-right direction and shorter in the up-down direction as shown in Figure 1. Figure 1 is a schematic representation of the waveguide substrate 10, and the ratio of the first direction to the width direction is not limited to the ratio shown in Figure 1.

The first region 1a is provided on one end of the cladding 1 in the first direction. The first region 1a is the region for mounting the first optical element. Here, "one end" refers to the end of the cladding 1 in the first direction, which in Figure 1 is the left end of the cladding 1. The direction closer to this end of the cladding 1 is referred to as the "one end side." The "other end" refers to the end of the cladding 1 opposite to the one end, which in Figure 1 is the right end of the cladding 1. The direction closer to this other end of the cladding 1 is referred to as the "other end side."

The second region 1b is located on the other end of the cladding 1 in the first direction. The second region 1b is the region for mounting the second optical element.

The first mirror 3 reflects the light propagating through the core 2 between the first region 1a and the second region 1b within the first region 1a, in a direction perpendicular to the first main surface 1c of the cladding 1.

The second mirror 4 is positioned adjacent to one end of the first mirror 3 in the first direction. The second mirror 4 reflects light propagating from the core 2 within the first region 1a along one end of the first mirror 3 in the first direction, in a direction perpendicular to the first main surface 1c of the cladding 1 within the first region 1a.

The third mirror 5 reflects the light incident on the cladding 1. This reflected light is directed towards the second mirror 4 within the core 2. The location where light is incident on the cladding 1 is between one end of the first region 1a of the first main surface 1c in the first direction and one end of the cladding 1 in the first direction.

The fourth mirror 6 reflects the light propagated through the core 2 between the first region 1a and the second region 1b in a direction perpendicular to the first main surface 1c of the cladding 1 within the second region 1b.

The fifth mirror 7 is positioned adjacent to the other end of the fourth mirror 6. The fifth mirror 7 reflects light propagating from the second region of the core 2 towards the other end into the first region 1a. The direction of the reflected light is positioned adjacent to the other end of the fourth mirror 6 in the first direction. The fifth mirror 7 reflects light propagating from the core 2 within the second region 1b towards the other end of the fourth mirror 6 in the first direction, in a direction perpendicular to the first main surface 1c of the cladding 1 within the second region 1b.

The sixth mirror 8 reflects the light incident on the cladding 1. This reflected light is directed towards the fifth mirror 7 within the core 2. The location where light is incident on the cladding 1 is between the other end of the second region 1b of the first main surface 1c in the first direction and the other end of the cladding 1 in the first direction.

Next, the alignment of the first optical element 20 on the waveguide substrate 10 will be explained. Figure 2 shows an example where signal light S is emitted from the second optical element 30 and received by the first optical element 20. The signal light S is emitted from the second optical element 30, reflected by the fourth mirror 6, propagates through the core 2 between the second region 1b and the first region 1a, is reflected by the first mirror 3, and is received by the first optical element 20. To form this optical path, it is necessary to align the first optical element 20 with respect to the first mirror 3 and the second optical element 30 with respect to the fourth mirror 6 during mounting. Alignment light P is used for these alignments.

As shown in Figure 2, the alignment light P for aligning the first optical element 20 is incident on the first main surface 1c of the cladding 1 from the region between the first region 1a and one end. More specifically, the alignment light P is incident on the region including the third mirror.

Alignment light P, incident on the cladding 1 from the first main surface 1c, is reflected by the third mirror 5. Next, the alignment light P propagates through the core 2. Then, it is reflected by the second mirror 4. Finally, the alignment light P is emitted from the first main surface 1c within the first region. The position of the second mirror 4 can be determined based on the image of this emitted alignment light P. The positional relationship between the first mirror 3 and the second mirror 4 is known. Therefore, the position of the first mirror 3 can be determined. The first mirror 3 is in the optical path of the signal light S. Therefore, by aligning the first optical element 20 with the position of the first mirror 3 as a reference, the first optical element 20 is aligned to the target optical path. Similarly, by incidenting alignment light P from the first main surface 1c from the other end of the second region 1b and reflecting it by the sixth mirror, the second optical element 30 is aligned.

Next, we will describe specific configuration examples of each part of the waveguide substrate 10. The waveguide substrate 10 shown in Figure 1 has four cores 2. Each core 2 has a first mirror 3, a second mirror 4, a third mirror 5, a fourth mirror 6, a fifth mirror 7, and a sixth mirror 8 formed on it.

Core 2 is the optical path for transmitting light. The constituent materials of Core 2 include organic materials such as epoxy resins, high-purity polyimide resins, polyamide resins, polyether resins, and silicone resins. Inorganic materials such as quartz glass, borosilicate glass, and silicon are also used as constituent materials for Core 2.

Cladding 1 has a lower refractive index than core 2. This difference in refractive index causes total internal reflection of light at the interface between core 2 and cladding 1, confining the light to core 2. For example, cladding 1 can be made from a material similar to core 2, but with its refractive index adjusted to be lower.

The first through sixth mirrors change the optical path of light propagating through core 2 by 90°. In other words, these mirrors transform the optical path. For this reason, these mirrors are sometimes called optical path transforming means.

Next, a modified example of the waveguide substrate 10 will be described. Figure 4 is a schematic cross-sectional view showing a waveguide substrate 10a, which is a modified example of the waveguide substrate 10 of the first embodiment. Similar to the waveguide substrate 10 in Figures 1-3, the waveguide substrate 10a includes a cladding 1, a core 2, a first mirror 3, a second mirror 4, a third mirror 5, a fourth mirror 6, a fifth mirror 7, and a sixth mirror 8.

In addition, the waveguide substrate 10a has a coating layer 40 on the first main surface of the cladding 1. Furthermore, the waveguide substrate 10a has a coating layer 41 on the second main surface of the cladding 1. The coating layer 40 is translucent. The coating layer 41 may be translucent or opaque. The coating layers 40 and 41 are composed of, for example, polyimide or PET (polyethylene terephthalate).

Furthermore, a first terminal 50 for mounting the first optical element 20 is provided in the first region 1a of the coating layer 40. Similarly, a second terminal 51 for mounting the second optical element 30 is provided in the second region 1b of the coating layer 40. Although not shown in the figures, circuits other than the first terminal 50 and the second terminal 51 may be formed on the coating layer 40. The first terminal 50 and the second terminal 51 are formed of, for example, copper, aluminum, nickel, gold, etc.

Next, a method for manufacturing an optical module in which the first optical element 20 and the second optical element 30 are mounted on a waveguide substrate 10a will be described. Figure 5 is a schematic cross-sectional view showing an example of a manufacturing method for the optical module 100 of the first embodiment. In the example in Figure 5, a waveguide substrate 10a is used.

First, alignment light P is incident on the first main surface 1c from the region between the first region 1a and one end. Next, the alignment light P is reflected by the third mirror 5. Then, the alignment light P passes through the core 2. Next, the alignment light P is reflected by the second mirror 4. Finally, the alignment light P is emitted from the first main surface 1c within the first region 1a. This emitted alignment light P is photographed by the camera 60, and the position of the second mirror 4 is determined. The positional relationship between the first mirror 3 and the second mirror 4 is known. Therefore, the position of the first mirror 3 is determined by the above operation. Based on this position of the first mirror 3, the alignment of the first optical element 20 is performed.

Furthermore, in at least one of the multiple cores 2, the first terminal 50 does not need to be formed at the position corresponding to the second mirror 4. This makes it easier to observe the alignment light P. Similarly, in at least one of the multiple cores 2, the second terminal 51 does not need to be formed at the position corresponding to the fifth mirror 7.

Figure 6 is a schematic cross-sectional diagram showing the relationship between the alignment light P and the signal light S in the first embodiment. In Figure 6, the first direction is the x-axis, and the width direction of the cladding 1 perpendicular to the x-axis is the y-axis. Also, the first mirror 3 and the second mirror 4 are assumed to be aligned in the x-direction. As shown in Figure 6, the alignment light P is emitted from the location at coordinates (x1, y1). These coordinates (x1, y1) are obtained from the image captured by the camera 60. As shown in Figure 6, in this example, the distance between the emission point of the alignment light P and the emission point of the signal light S is d. From the above, the coordinates (x1 + d, y1) of the location from which the signal light S is emitted are calculated. By using these coordinates as a reference, the first optical element can be aligned.

Figure 7 is a schematic cross-sectional view of the optical module 100 according to the first embodiment. The first optical element 20 and the second optical element 30, aligned using the method shown in Figure 5, are mounted on the waveguide substrate 10a. In the example in Figure 5, the terminals of the first optical element 20 are joined to the first terminal 50 of the first region 1a, and the terminals of the second optical element 30 are joined to the second terminal 51 of the second region 1b. In the above description, the first optical element 20 was a light-receiving element and the second optical element 30 was a light-emitting element; however, the relationship between the light-emitting and light-receiving elements may be reversed. Furthermore, a laser diode can be used as the light-emitting element, for example. A photodiode can be used as the light-receiving element, for example.

Next, a method for preventing stray light from entering the optical module 100 will be described. Figure 8 is a schematic cross-sectional view showing a first modified example of the optical module 100 in one embodiment. After the mounting of the first optical element 20 and the second optical element 30 is complete, the alignment light P is no longer needed. Furthermore, light entering from the optical path of the alignment light P becomes noise (stray light) in the signal light S. Therefore, it is necessary to block the light entering the optical path of the alignment light P. The configuration in Figure 8 is an example of a configuration for blocking stray light. Light-shielding members 70 are provided at the corresponding positions of the third mirror 5 and the sixth mirror 8 on the coating layer 40. These light-shielding members 70 block the entry of stray light.

Figure 9 is a schematic cross-sectional view showing a second modified example of the optical module of the first embodiment. In the optical module 100b of the example in Figure 9, a non-transparent component 71 is mounted instead of the light-shielding member 70 in Figure 8. Even with this configuration, the optical module 100b can prevent the entry of stray light, similar to the optical module 100a.

Figure 10 is a schematic cross-sectional view showing the first state of a third modified example of the optical module of the first embodiment. In the optical module 100c of Figure 10, a first discontinuity 11 is provided in the core 2 between the second mirror 4 and the third mirror 5. This first discontinuity 11 is formed after the mounting of the first optical element 20 and the second optical element 30. However, if the alignment light P can propagate through the core 2 beyond the first discontinuity 11, the first discontinuity 11 may be formed before the mounting of the first optical element 20 and the second optical element 30. Similarly to the first discontinuity 11, a second discontinuity 12 is provided in the core 2 between the fifth mirror 7 and the sixth mirror 8.

Figure 11 is a schematic cross-sectional view showing the second state of a third modified example of the waveguide substrate of the first embodiment. In the second state, the first discontinuity 11 is filled with light-shielding material 72, and the second discontinuity 12 is also filled with light-shielding material 72. The light-shielding material 72 blocks the optical path from the third mirror 5 to the second mirror 4. Similarly, the light-shielding material 72 blocks the optical path from the sixth mirror 8 to the fifth mirror 7. In this way, the optical module 100c can prevent stray light from entering the first optical element 20 and the second optical element 30.

The waveguide substrate 10 and other components of this embodiment have been described above.

The waveguide substrate 10 of this embodiment includes a cladding 1, a core 2, a first mirror 3, a second mirror 4, and a third mirror 5. The cladding 1 is provided with a first region 1a and a second region 1b. The cladding 1 is in the form of a sheet. The core 2 is surrounded by the cladding. The core 2 extends in a first direction. The first region 1a is provided on one end of the cladding 1 in the first direction. The first region 1a is a region for mounting a first optical element. The second region 1b is provided on the other end of the cladding 1 in the first direction. The second region 1b is a region for mounting a second optical element. The first mirror 3 reflects light propagating through the core 2 between the first region 1a and the second region 1b back into the first region 1a. The direction of the reflected light is perpendicular to the first main surface 1c of the cladding 1. The second mirror 4 is positioned adjacent to the one end of the first mirror 3. Within the first region 1a, the second mirror 4 reflects light perpendicular to the first main surface 1c. This light propagates from the first region 1a of the core 2 towards the one end. The third mirror 5 reflects light within the core 2. The incident light to the third mirror 5 is light that entered the cladding 1 from one end of the first region 1a. The incident light is reflected towards the second mirror 4.

In the above configuration, alignment light P incident from the first main surface 1c passes through the third mirror 5, core 2, and second mirror 4, and is emitted to the first region 1a. The position of this emitted light is captured by a camera, allowing the position of the second mirror to be determined. Then, the position of the first mirror 3 can be determined from the positional relationship between the first mirror 3 and the second mirror 4. The first mirror 3 is in the optical path of the first optical element 20. Therefore, by aligning the first optical element 20 to the determined position of the first mirror 3, the first optical element 20 can be accurately aligned to the waveguide substrate 10. Furthermore, this method does not increase the width of the waveguide substrate 10, unlike the method described in Patent Document 1.

In another embodiment, the waveguide substrate 10 includes a fourth mirror 6, a fifth mirror 7, and a sixth mirror 8. The fourth mirror 6 reflects light propagated through the core 2 between the first region 1a and the second region 1b in a direction perpendicular to the first main surface 1c of the cladding 1 within the second region 1b. The fifth mirror 7 is positioned adjacent to the other end of the fourth mirror 6 in the first direction. The fifth mirror 7 also reflects light propagated from the core 2 in the second region 1b along the other end of the fourth mirror 6 in the first direction in a direction perpendicular to the first main surface 1c of the cladding 1 within the second region 1b. The sixth mirror 8 reflects light within the core 2. The incident light on the sixth mirror 8 is light incident on the cladding 1 from the other end of the second region 1b. The incident light is reflected toward the second mirror 4.

In the above configuration, the position of the fifth mirror 7 can be determined by photographing the position of the emitted light reflected by the fifth mirror 7 with a camera. Then, the position of the fourth mirror 6 can be determined from the positional relationship between the fourth mirror 6 and the fifth mirror 7. The fourth mirror 6 is in the optical path of the second optical element 30. Therefore, by aligning the second optical element 30 with the position of the fourth mirror 6, the second optical element 30 can be accurately positioned on the waveguide substrate 10. Furthermore, this method does not increase the width of the waveguide substrate 10, unlike in Patent Document 1.

In another embodiment, the waveguide substrate 10 has a first discontinuity 11 where the core 2 is discontinuous between the second mirror 4 and the third mirror 5. Furthermore, the waveguide substrate 10 has a second discontinuity 12 where the core 2 is discontinuous between the fifth mirror 7 and the sixth mirror 8. In this configuration, after the alignment of the first optical element 20 and the second optical element 30 is completed, the first discontinuity 11 and the second discontinuity 12 are filled with a light-shielding material 72. The action of this light-shielding material 72 prevents stray light passing through the third mirror 5 and the sixth mirror 8 from entering the core 2.

In another embodiment, a translucent coating layer 40 is formed on the first main surface 1c of the cladding 1 of the waveguide substrate 10a. A first terminal 50 for mounting a first optical element is formed in a first region 1a of the coating layer 40. A second terminal 51 for mounting a second optical element is formed in a second region 1b of the coating layer 40. By providing the first terminal 50 and the second terminal 51, the first optical element 20 and the second optical element 30 can be joined to the waveguide substrate 10a.

Furthermore, the optical module 100 of this embodiment includes either a waveguide substrate 10 or a waveguide substrate 10a, a first optical element 20, and a second optical element 30. The first optical element 20 is aligned with the first mirror 3 and mounted in the first region. The second optical element 30 is aligned with the fourth mirror 6 and mounted in the second region 1b. This configuration optically couples the first optical element 20 and the second optical element 30.

Furthermore, the manufacturing method of the optical module in this embodiment is a method for manufacturing an optical module in which optical elements are mounted on a waveguide substrate 10. The waveguide substrate 10 has a cladding 1, a core 2, a first mirror 3, a second mirror 4, and a third mirror 5. The cladding 1 is provided with a first region 1a and a second region 1b. The cladding 1 is in the form of a sheet. The core 2 is surrounded by the cladding. The core 2 extends in a first direction. The first region 1a is provided on one end of the cladding 1 in the first direction. The first region 1a is a region for mounting a first optical element. The second region 1b is provided on the other end of the cladding 1 in the first direction. The second region 1b is a region for mounting a second optical element. The first mirror 3 reflects light propagating through the core 2 between the first region 1a and the second region 1b back into the first region 1a. The direction of the reflected light is perpendicular to the first main surface 1c of the cladding 1. The second mirror 4 reflects light within the first region 1a in a direction perpendicular to the first main surface 1c. This light propagated from the first region 1a of the core 2 towards the aforementioned end. The direction of the reflected light is perpendicular to the first main surface 1c of the cladding 1. The third mirror 5 reflects light within the core 2. The incident light for the third mirror 5 is light that entered the cladding 1 from one end of the first region 1a. The incident light is reflected towards the second mirror 4. The manufacturing method of the optical module involves injecting alignment light P, which is light used to align the first optical element 20, from the first main surface 1c to the third mirror 5. Furthermore, the first optical element 20 is aligned to the first region 1a based on the position of the alignment light P emitted from the second mirror 4. This configuration allows the manufacturing method of the optical module in this embodiment to align the first optical element 20 and the second optical element 30 to the target position.

Furthermore, according to one embodiment, in the manufacturing method of the optical module of this embodiment, a light-shielding member 70 that prevents light from entering the second mirror 4 is attached after the mounting of the first optical element 20 is completed. With this configuration, the manufacturing method of the optical module of this embodiment can prevent stray light from entering the first optical element 20 and the second optical element 30.

In another embodiment, the manufacturing method of the optical module of this embodiment involves placing the light-shielding member 70 between the second mirror 4 and the third mirror 5. This configuration allows the manufacturing method of the optical module of this embodiment to prevent stray light from entering the first optical element 20 and the second optical element 30.

As described above, the waveguide substrate 10 of this embodiment allows for a narrower width of the waveguide substrate 10 compared to the technology described in Patent Document 1. Furthermore, compared to the technology described in Patent Document 2, it is possible to provide a waveguide substrate 10 that allows for more accurate positioning of the first optical element 20 and the second optical element 30.

(Second embodiment)
Figure 11 is a schematic cross-sectional view showing a waveguide substrate of the second embodiment. The waveguide substrate 10 includes a cladding 1, a core 2, a first mirror 3, a second mirror 4, and a third mirror 5. The cladding 1 is provided with a first region 1a and a second region 1b. Here, the cladding 1, core 2, first mirror 3, second mirror 4, and third mirror 5 of the first embodiment are examples of the cladding 1, core 2, first mirror 3, second mirror 4, and third mirror 5 of this embodiment, respectively. Also, the first region 1a and second region 1b of the first embodiment are examples of the first region 1a and second region 1b of this embodiment.

Cladding 1 is sheet-like. Core 2 is surrounded by the cladding. Core 2 extends in a first direction.

The first region 1a is provided on one end of the cladding 1 in the first direction. The first region 1a is a region for mounting the first optical element.

The second region 1b is located on the other end of the cladding 1 in the first direction. The second region 1b is the region for mounting the second optical element.

The first mirror 3 reflects the light propagating through the core 2 between the first region 1a and the second region 1b within the first region 1a, in a direction perpendicular to the first main surface 1c of the cladding 1.

The second mirror 4 is positioned adjacent to one end of the first mirror 3 in the first direction. The second mirror 4 reflects light propagating from the core 2 within the first region 1a along one end of the first mirror 3 in the first direction, in a direction perpendicular to the first main surface 1c of the cladding 1 within the first region 1a.

The third mirror 5 reflects the light incident on the cladding 1. This reflected light is directed towards the second mirror 4 within the core 2. The location where light is incident on the cladding 1 is between one end of the first region 1a of the first main surface 1c in the first direction and one end of the cladding 1 in the first direction.

The waveguide substrate and other components of this embodiment have been described above.

The waveguide substrate 10 comprises a cladding 1, a core 2, a first mirror 3, a second mirror 4, and a third mirror 5. The cladding 1 is provided with a first region 1a and a second region 1b. The cladding 1 is sheet-like. The core 2 is surrounded by the cladding and extends in a first direction. The first region 1a is provided on one end of the cladding 1 in the first direction. The first region 1a is a region for mounting a first optical element. The second region 1b is provided on the other end of the cladding 1 in the first direction. The second region 1b is a region for mounting a second optical element. The first mirror 3 reflects light propagating through the core 2 between the first region 1a and the second region 1b in the first region 1a in a direction perpendicular to the first main surface 1c of the cladding 1. The second mirror 4 is positioned adjacent to one end of the first mirror 3 in the first direction. The second mirror 4 reflects light propagating from the core 2 in the first region 1a along one end of the first mirror 3 in the first direction, in a direction perpendicular to the first main surface 1c of the cladding 1 within the first region 1a. The third mirror 5 reflects light within the core 2. The incident light for the third mirror 5 is light that entered the cladding 1 from one end of the first region 1a. The incident light is reflected towards the second mirror 4.

In the above configuration, light incident on the cladding 1 from one end of the first region of the first main surface 1c in the first direction passes through the third mirror 5, core 2, and second mirror 4, and exits to the first region. By photographing the position of this exiting light with a camera, the position of the second mirror 4 can be determined. Then, the position of the first mirror 3 can be determined from the positional relationship between the first mirror 3 and the second mirror 4. The first mirror 3 is in the optical path of the first optical element 20. Therefore, by aligning the first optical element 20 to the determined position of the first mirror, the first optical element 20 can be accurately positioned on the waveguide substrate 10. Furthermore, this method does not increase the width of the waveguide substrate 10, as described in Patent Document 1. Also, compared to the technology in Patent Document 2, this method provides a waveguide substrate 10 that allows for more accurate positioning of the first optical element 20 and the second optical element 30.

The first and second embodiments have been described above as exemplary examples of the present invention. However, the present invention is not limited to the above embodiments. That is, the present invention can be applied in various forms that can be understood by those skilled in the art, within the scope of the present invention.

1. Cladding 2. Core 3. First mirror 4. Second mirror 5. Third mirror 6. Fourth mirror 7. Fifth mirror 8. Sixth mirror 10. Waveguide substrate 20. First optical element 30. Second optical element 40, 41. Coating layer 50. First terminal 51. Second terminal 60. Camera 70. Light-shielding member 100. Optical module

Claims (9)

A sheet-like cladding,
A core surrounded by the cladding and extending in a first direction,
To mount the first optical element, a first region is provided on one end side of the cladding in the first direction,
In order to mount the second optical element, a second region is provided on the other end side of the cladding in the first direction,
A first mirror that reflects light propagating through the core between the first region and the second region in a direction perpendicular to the first main surface of the cladding within the first region,
A second mirror is positioned adjacent to one end of the first mirror in the first direction, and reflects light propagating from the core in the first region through one end of the first mirror in the first direction in a direction perpendicular to the first main surface of the cladding within the first region.
A third mirror in the core reflects light incident on the cladding from between one end of the first region of the first main surface in the first direction and one end of the cladding in the first direction toward the second mirror,
The first light-shielding means prevents light from entering the second mirror,
A waveguide substrate characterized by having the following features. A fourth mirror that reflects light propagating through the core between the first region and the second region in a direction perpendicular to the first main surface of the cladding within the second region,
A fifth mirror is positioned adjacent to the other end of the fourth mirror in the first direction, and reflects light propagating from the core in the second region along the other end of the fourth mirror in the first direction in a direction perpendicular to the first main surface of the cladding within the second region.
A sixth mirror that reflects light incident on the cladding from between the other end of the second region of the first main surface in the first direction and the other end of the cladding in the first direction towards the fifth mirror within the core,
A second light-shielding means for preventing light from entering the fifth mirror,
Waveguide substrate according to claim 1, characterized by having the following features. The first light-shielding means is a light-shielding member provided on the first main surface that prevents light from entering the second mirror,
The second light-shielding means is a light-shielding member provided on the first main surface that prevents light from entering the fifth mirror.
Waveguide substrate according to claim 2. The first light-shielding means is configured to have a first discontinuity between the second mirror and the third mirror where the core is discontinuous, and a light-shielding material filled in the first discontinuity.
The second light-shielding means is configured to have a second discontinuity in the core between the fifth mirror and the sixth mirror, and a light-shielding material filled in the second discontinuity.
Waveguide substrate according to feature 2. A translucent coating layer is formed on the first main surface of the cladding.
A first terminal for mounting the first optical element is formed in the first region of the coating layer.
A second terminal for mounting the second optical element is formed in the second region of the coating layer.
Waveguide substrate according to any one of claims 2 to 4 . A waveguide substrate according to any one of claims 2 to 5 ,
The first optical element mounted in the first region,
The second optical element mounted in the second region,
An optical module characterized by having the following features. A method for manufacturing an optical module in which optical elements are mounted on a waveguide substrate,
The waveguide substrate is
A sheet-like cladding,
A core surrounded by the cladding and extending in a first direction,
To mount the first optical element, a first region is provided on one end side of the cladding in the first direction,
In order to mount the second optical element, a second region is provided on the other end side of the cladding in the first direction,
A first mirror that reflects light propagating through the core between the first region and the second region in a direction perpendicular to the first main surface of the cladding within the first region,
A second mirror is positioned adjacent to one end of the first mirror in the first direction, and reflects light propagating from the core in the first region through one end of the first mirror in the first direction in a direction perpendicular to the first main surface of the cladding within the first region.
A third mirror in the core reflects light incident on the cladding from between one end of the first region of the first main surface in the first direction and one end of the cladding in the first direction toward the second mirror,
It has,
Alignment light, which is light for aligning the first optical element, is incident from the first main surface to the third mirror.
Based on the position of the alignment light emitted from the second mirror, the first optical element is aligned to the first region.
After the mounting of the first optical element is completed, a first light-shielding means is provided to prevent light from entering the second mirror.
A method for manufacturing an optical module, characterized by the following: The first light-shielding means is a light-shielding member provided on the first main surface that prevents light from entering the second mirror.
The method for manufacturing an optical module according to feature 7 . The first light-shielding means is configured to have a first discontinuity between the second mirror and the third mirror where the core is discontinuous, and a light-shielding material filled in the first discontinuity.
The method for manufacturing an optical module according to feature 7 .