JP7192270B2 - Optical waveguides, optical modules and electronics - Google Patents

Description

The present invention relates to optical waveguides, optical modules and electronic devices.

In the optical waveguide, light introduced from one end of the core portion is conveyed to the other end while being reflected at the boundary with the clad portion. A light-emitting element such as a semiconductor laser is arranged on the incident side of the optical waveguide, and a light-receiving element such as a photodiode is arranged on the outgoing side. Light incident from the light-emitting element propagates through the optical waveguide, is received by the light-receiving element, and performs optical communication based on the flickering pattern of the received light or its intensity pattern.

In such optical communication, the characteristics of the light-emitting element may change due to factors such as the external environment and aging, and the intensity of light incident on the optical waveguide may change accordingly. Such a change in light intensity causes deterioration in the stability of optical communication.

Therefore, in Patent Document 1, a light emitting element, a main waveguide core for propagating light emitted from the light emitting element, a monitor waveguide core branched from the main waveguide core, and a light emitted from the monitor waveguide core and a hole serving as a reflecting surface for changing the propagation direction of light propagating through the main waveguide core. Since this optical waveguide module has a monitoring waveguide core branched from a main waveguide core, it is possible to perceive the temporal change in the light emission intensity of the light emitting element. This makes it possible to control the driving of the light-emitting element so that the light emission intensity becomes constant, for example.

JP 2007-057760 A

However, in the optical waveguide module described in Patent Document 1, Fresnel reflection at the interface (reflection portion) between the main waveguide core (main line core portion) and the air holes is used to change the propagation direction of light within the plane of the optical waveguide. are converting. For this reason, it is necessary to secure a large space for arranging holes and waveguide cores (branch line core portions) for monitoring, which makes it difficult to reduce the size of the optical waveguide module. In particular, in order to miniaturize the optical waveguide module, it is necessary to miniaturize the air holes as well. In addition, the width of the main waveguide core must be widened to some extent for the provision of the holes, and there is also the problem that it is difficult to increase the arrangement density when the main waveguide cores are arranged in parallel.

Furthermore, since it is not easy to improve the surface accuracy of minute reflecting surfaces, there is a problem that excessive loss is large in optical path conversion using Fresnel reflection.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a miniaturized optical waveguide with a small excess loss, and a highly reliable optical module and electronic equipment having such an optical waveguide.

Such objects are achieved by the present invention of the following (1) to (9).
(1) a first optical path changing core portion having a first reflecting portion inside;
a main line core portion extending from the first optical path-changing core portion and optically connected to the first reflecting portion and having a width smaller than both the first optical path-changing core portion and the first reflecting portion ;
Extending from the first optical path-changing core portion and optically connected to the first reflecting portion, having a smaller width than both the first optical path-changing core portion and the first reflecting portion , and the main line core a branch line core portion spaced apart from the portion;
a second optical path changing core portion having a second reflecting portion inside;
having a core layer formed with a branched pattern comprising
The length of the main line core portion is longer than the length of the branch line core portion,
In a plan view of the core layer, the branch pattern is such that the entire width of the extension line of the main line core portion and part of the width of the extension line of the branch line core portion intersect the first reflecting portion. is formed and
Light from the light-emitting element enters the main line core portion and the branch line core portion through the first reflecting portion, and light from the branch line core portion enters the light receiving element through the second reflecting portion. An optical waveguide characterized by being used as follows.

(2) The optical waveguide according to (1) above, wherein the main line core portion has a width of 20 to 80 μm.
(3) The optical waveguide according to (1) or (2) above , wherein the main material of the core layer is a resin material .

(4) The optical waveguide according to any one of (1) to (3) above, wherein the branch line core portion has a length of 800 to 10000 μm.

(5) A straight line connecting the center point of the width of the main line core portion at the boundary with the optical path-changing core portion and the center point of the width at a position 50 μm from the optical path-changing core portion is defined as a virtual straight line,
When the aggregate of the center points of the width of the branch line core portion is defined as the branch line central axis,
When the branch line core portion moves away from the optical path changing core portion along its extending direction, the acute angle side of the angle formed by the tangent to the central axis of the branch line and the imaginary straight line in plan view of the core layer is A first curved portion that gradually decreases in size, and a second curved portion that gradually increases in angle formed by a tangent to the central axis of the branch line and the imaginary straight line in a plan view of the core layer. and a two-shaped curved portion.

(6) comprising a first recess and a second recess penetrating the core layer in the thickness direction ;
The first reflecting portion is a part of the inner surface of the first concave portion,
The optical waveguide according to any one of (1) to (5) above, wherein the second reflecting portion is part of the inner surface of the second concave portion.

(7) The optical waveguide according to any one of (1) to (6) above, wherein the core layer includes a plurality of branch patterns arranged along a direction crossing the extending direction of the main line core portion.

(8) the optical waveguide according to any one of (1) to (7);
a light emitting element optically connected to the reflecting section;
a light receiving element optically connected to the branch line core portion;
An optical module characterized by comprising:

(9) An electronic device comprising the optical waveguide according to any one of (1) to (7) above.

According to the present invention, it is possible to obtain a compact optical waveguide with a small excess loss.
Moreover, according to the present invention, a highly reliable optical module and electronic equipment can be obtained.

1 is a cross-sectional view showing an embodiment of an optical module of the present invention; FIG. 2 is a plan view showing a portion of the optical module shown in FIG. 1 excluding a housing and a receptacle; FIG. 3 is a plan view of the optical waveguide shown in FIG. 2; FIG. 4 is a partially enlarged perspective view of the optical waveguide shown in FIG. 3; FIG. It is a figure which expands and shows the branch line core part shown in FIG. FIG. 6 is a diagram schematically emphasizing a second shape curved portion shown in FIG. 5; FIG. 6 is a diagram schematically emphasizing a first shape curved portion shown in FIG. 5;

BEST MODE FOR CARRYING OUT THE INVENTION An optical waveguide, an optical module, and an electronic device according to the present invention will be described below in detail based on preferred embodiments shown in the accompanying drawings.

<Optical module>
First, embodiments of the optical module of the present invention and embodiments of the optical waveguide of the present invention will be described.

FIG. 1 is a cross-sectional view showing an embodiment of an optical module of the present invention. 2 is a plan view showing a portion of the optical module shown in FIG. 1, excluding a housing and a receptacle.

The optical module 100 (optical module according to the embodiment) shown in FIG. It has a light receiving element 32 , a control element 4 , a lens array 5 , a receptacle 61 and a housing 7 . In such an optical module 100, the light emitted from the light emitting element 31 is introduced into the optical waveguide 1, and is internally divided into light for communication and light for monitoring. The light for monitoring is received by the light receiving element 32, and while monitoring the light intensity, sufficient light intensity is ensured for the light for communication, thereby enabling high-quality optical communication.

Among these, the electric board 2 shown in FIG.

A light-emitting element 31, a light-receiving element 32, and a control element 4 are mounted on the upper surface of the electric substrate 2 shown in FIG. These elements and the conductive layer 22 are electrically connected via bonding wires (not shown). Note that this connection structure is not limited to bonding wires, and may be replaced by other structures such as flip-chip bonding.

Examples of the light emitting element 31 include a surface emitting laser (VCSEL), a light emitting diode (LED), an organic EL element, and the like.

Moreover, as the light receiving element 32, for example, a photodiode (PD, APD), a phototransistor, or the like can be used.

Also, the control element 4 may be, for example, a driver IC, a transimpedance amplifier (TIA), a limiting amplifier (LA), or a combination IC combining these elements.

In addition to the elements described above, the electric board 2 is equipped with a CPU (central processing unit), MPU (microprocessor unit), LSI, IC, RAM, ROM, capacitors, coils, resistors, diodes, and the like. good too.

A contact 23 electrically connected to the conductive layer 22 is provided at the left end of the electric substrate 2 shown in FIG. The portion provided with the contact 23 is inserted into and engaged with an electrical connector 82 attached to the right end of the electrical wiring 81 shown in FIG. Thus, electrical connection is established between the electrical board 2 and the electrical wiring 81 via the electrical connector 82 . As a result, the optical module 100 is electrically connected to the outside.

On the other hand, the optical waveguide 1 shown in FIGS. 1 and 2 has a sheet shape, and a core portion 14 formed inside serves as an optical waveguide.

An MT type optical connector 62 is attached to the right end of the optical waveguide 1 . This MT type optical connector 62 is inserted into the receptacle 61 from its left side. That is, an MT type receiving portion 611 is formed on the left side of the receptacle 61 and the MT type optical connector 62 is inserted into the MT type receiving portion 611 .

Further, the optical waveguide 1 is formed with a reflecting portion 16a (first reflecting portion) . The optical path P1 extending horizontally in FIG. 1 is converted into an optical path P2 extending vertically in FIG. The optical path P2 optically connects the optical waveguide 1 with the light emitting element 31 and the light receiving element 32, respectively. The optical paths P1 and P2 shown in FIG. 1 are examples of paths along which light propagates.

A lens array 5 is provided between the optical waveguide 1 and the electric substrate 2 . The lens array 5 shown in FIG. 1 includes a bottom portion 51 and a wall portion 52 erected downward from the edge of the bottom portion 51 . The bottom surface of the wall portion 52 is bonded to the top surface of the electric substrate 2 , and the optical waveguide 1 is bonded to the top surface of the bottom portion 51 . Thereby, a cavity 53 surrounded by the bottom portion 51, the wall portion 52 and the electric substrate 2 is formed. Further, the light emitting element 31, the light receiving element 32, and the control element 4 described above are accommodated in this cavity 53. As shown in FIG. As a result, the light emitting element 31, the light receiving element 32, and the control element 4 can be protected from the external environment, adhesion of foreign matter, and the like.

The lens array 5 is light transmissive and allows the optical path P2 to pass therethrough. A lens 54 is formed on the bottom portion 51 . This lens 54 is, for example, a convex lens, and can focus the light propagating along the optical path P2 to a target position.

In addition to the lens 54, the lens array 5 may be provided with a diffraction grating, a polarizer, a prism, a filter, and the like.

An MPO type receiving portion 612 is formed on the right side of the receptacle 61 . An MPO type optical connector 92 attached to the left end of the optical fiber 91 is inserted and fitted into the MPO type receiving portion 612 . Thereby, the optical fiber 91 and the optical waveguide 1 are optically connected. As a result, the optical module 100 is optically connected to the outside.

The housing 7 is a box-shaped member that accommodates each part except for the electric wiring 81 , the electric connector 82 , the optical fiber 91 and the MPO type optical connector 92 . By housing the optical module 100 in such a housing 7, each part can be protected from the external environment, and the reliability and portability of the optical module 100 can be enhanced.

A through hole is provided in a part of the housing 7, and a portion of the electric board 2 provided with the contact 23 protrudes therefrom. Thereby, the electrical connector 82 can be easily attached to the contact 23 . Similarly, an MPO type receiving portion 612 of the receptacle 61 is exposed through a through hole provided in a portion of the housing 7 . As a result, the optical fiber 91 can be easily connected to the optical module 100 simply by inserting the MPO type optical connector 92 into the MPO type receiving portion 612 .

Examples of materials constituting the housing 7 include metal materials such as stainless steel, aluminum alloys, and titanium alloys, as well as various resin materials and various ceramic materials.
<Optical waveguide>
Next, the optical waveguide 1 will be explained.

3 is a plan view of the optical waveguide shown in FIG. 2. FIG. 4 is a partially enlarged perspective view of the optical waveguide shown in FIG.

As described above, the optical waveguide 1 has a sheet shape, and allows the light emitted from the bottom to the top in FIG. 3 to enter the core portion 14 for communication.

The optical waveguide 1 according to the present embodiment is a laminate in which a lower protective layer 17, a clad layer 11, a core layer 13, a clad layer 12, and an upper protective layer 18 are laminated in this order from the bottom of FIG. 10. In the core layer 13, an elongated core portion 14 extending in the vertical direction in FIG. A cladding portion 15 is formed.

On the other hand, the optical waveguide 1 shown in FIGS. 3 and 4 includes the reflecting portion 16a for converting between the optical path P1 and the optical path P2 shown in FIG. 1, as described above. As shown in FIG. 4, the reflecting portion 16a is a part of the inner surface of a concave portion 160 that opens in the upper surface of the laminate 10 and penetrates the core layer 13. As shown in FIG. In other words, the reflecting portion 16a is a portion of the interface between the hollow recess 160 and the core portion 14 . Therefore, in the reflecting portion 16a, the light path P1 and the light path P2 can be mutually converted by Fresnel reflection based on the refractive index difference. Specifically, the optical path P1 extending in the horizontal direction in FIG. 1 and the optical path P2 extending in the vertical direction in FIG. 1 are mutually converted.

Each part of the optical waveguide 1 will be described in further detail below.
-Core layer-
Core portion 14 formed in core layer 13 shown in FIG. The refractive index of the core portion 14 is higher than that of the side clad portion 15 and the clad layers 11 and 12 . Thereby, light can be confined in the core portion 14 and propagated.

In the core layer 13, the refractive index distribution in the plane orthogonal to the optical path P1 may be any distribution, for example, a so-called step index (SI) type distribution in which the refractive index changes discontinuously. , a so-called graded index (GI) type distribution in which the refractive index changes continuously.

In addition, the cross-sectional shape of the core portion 14 perpendicular to the optical path P1 is not particularly limited, and other than the quadrangle shown in the figure, it may be a circle such as a perfect circle, an ellipse, an oval, a triangle, a quadrangle, a pentagon, a hexagon, or the like. Polygons and other irregular shapes may also be used.

Further, when the core layer 13 is viewed from the thickness direction, the core portion 14 is branched into two at a widened portion 141 which will be described later. Thereby, the optical signal can be divided into two. This branch structure will be detailed later.

Although the average thickness of the core layer 13 is not particularly limited, it is preferably about 1 to 200 μm, more preferably about 5 to 100 μm, even more preferably about 10 to 70 μm. As a result, it is possible to reduce the thickness of the optical waveguide 1 while suppressing a decrease in the transmission efficiency of the optical waveguide 1 .

Examples of the constituent material (main material) of the core layer 13 include acrylic resin, methacrylic resin, polycarbonate, polystyrene, cyclic ether resin such as epoxy resin and oxetane resin, polyamide, polyimide, polybenzoxazole, Polysilane, polysilazane, silicone resin, fluorine resin, polyurethane, polyolefin resin, polybutadiene, polyisoprene, polychloroprene, polyester such as polyethylene terephthalate (PET) and polybutylene terephthalate (PBT), polyethylene succinate, polysulfone, poly Various resin materials such as ethers and cyclic olefin resins such as benzocyclobutene resins and norbornene resins can be used. Composite materials, in which resin materials having different compositions are combined, are also used.

-Clad layer-
The average thickness of each of the clad layers 11 and 12 is preferably about 1 to 200 μm, more preferably about 3 to 100 μm, even more preferably about 5 to 60 μm. As a result, the functions of the clad layers 11 and 12 are ensured while preventing the optical waveguide 1 from becoming thicker than necessary.

As the constituent material of the clad layers 11 and 12, for example, the same material as the constituent material of the core layer 13 can be used. At least one selected from the group consisting of polyimide resins, fluorine resins, and polyolefin resins is preferable, and (meth)acrylic resins or epoxy resins are more preferable.

Note that the clad layers 11 and 12 may be provided as required, and may be omitted. At this time, for example, if the core layer 13 is exposed to the outside air (air), the outside air functions as the clad layers 11 and 12 .

- Protective layer -
In the optical waveguide 1 shown in FIG. 4, the lower protective layer 17 and the upper protective layer 18 protect the core layer 13 and the clad layers 11 and 12, thereby suppressing deterioration of the transmission efficiency of the core portion 14 due to the external environment and the like. can do.

Materials constituting the lower protective layer 17 and the upper protective layer 18 include, for example, polyolefins such as polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyethylene and polypropylene, and materials containing various resins such as polyimide and polyamide. mentioned.

Although the average thickness of the lower protective layer 17 and the upper protective layer 18 is not particularly limited, it is preferably about 5 to 500 μm, more preferably about 10 to 400 μm.

Also, the lower protective layer 17 and the upper protective layer 18 may have the same configuration or different configurations.

The lower protective layer 17 and the upper protective layer 18 may be provided as required, and at least one of them may be omitted.

- concave part -
The recess 160 is provided at the end in the extending direction of the core portion 14 . Reflecting portion 16 a provided on the inner surface of recess 160 is a surface that is inclined with respect to optical path P 1 of core portion 14 . The conversion angle of the optical path P1 can be adjusted according to the inclination angle of the reflecting portion 16a.

The concave portion 160 shown in FIG. 4 has a triangular shape with a downward vertex when viewed from a direction perpendicular to the optical path P1 in the plane of the core layer 13 . As shown in FIG. 4, the reflective portion 16a is a flat surface formed continuously from the clad layer 11 through the core layer 13 and the clad layer 12 to the upper protective layer 18 . Note that the shape of the recess 160 is not limited to the shape shown in FIG. 4, and may be any shape.

The angle of inclination of the reflecting portion 16a is not particularly limited, but when the lower surface of the optical waveguide 1 shown in FIG. It is preferably about 40 to 50°, more preferably about 40 to 50°. By setting the inclination angle within the above range, the optical path P1 of the core portion 14 can be efficiently converted at the reflecting portion 16a, and the loss associated with the optical path conversion can be suppressed.

The position of the deepest part of the concave portion 160 , that is, the position of the vertex of the triangle is not particularly limited, but is preferably at least closer to the clad layer 11 than the core layer 13 .

Further, the core layer 13 according to the present embodiment is provided with a widened portion 141 ( first optical path changing core portion) which is provided at a position corresponding to the concave portion 160 and is wider than the core portion 14 . That is, as shown in FIG. 3, when the core layer 13 is viewed from above, the widened portion 141 has a rectangular shape that includes the concave portion 160, and is adjacent to the upper end of the core portion 14 in FIG. there is The refractive index of the widened portion 141 is higher than that of the side clad portion 15 and the clad layers 11 and 12, like the core portion . By providing such a widened portion 141 , the material of the reflecting portion 16 a exposed in the cross section of the core layer 13 has a higher refractive index than the side clad portion 15 and the clad layers 11 and 12 . Therefore, the refractive index difference in the reflecting portion 16a can be increased, thereby increasing the reflectance and reducing the reflection loss.

Further, as shown in FIG. 3, the optical waveguide 1 according to the present embodiment is provided below a branch line core portion 194 to be described later, and the reflection portion 16b (second reflective part) . The reflecting portion 16b is a part of the inner surface of a recess 161 that opens in the upper surface of the laminate 10 shown in FIG. 4 and penetrates the core layer 13 . In other words, the reflecting portion 16b is a part of the interface between the hollow recess 161 and the core portion 14 . Therefore, in the reflecting portion 16b, the optical path P1 and the optical path P2 can be mutually converted by Fresnel reflection based on the refractive index difference. Specifically, the optical path P1 extending in the horizontal direction in FIG. 1 and the optical path P2 extending in the vertical direction in FIG. 1 are mutually converted.

Further, the core layer 13 according to the present embodiment is provided with a widened portion 142 (second optical path changing core portion) which is provided at a position corresponding to the concave portion 161 and is wider than the core portion 14 . That is, as shown in FIG. 3, when the core layer 13 is viewed from above, the widened portion 142 has a rectangular shape that includes the concave portion 161, and is adjacent to the lower end of the core portion 14 in FIG. there is The refractive index of the widened portion 142 is higher than that of the side clad portion 15 and the clad layers 11 and 12, like the core portion . By providing such a widened portion 142, the material exposed in the cross section of the core layer 13 in the reflective portion 16b is less than the material constituting the core portion 14, that is, the side clad portion 15 and the clad layers 11 and 12. It becomes a material with a high refractive index. Therefore, the refractive index difference in the reflecting portion 16b can be increased, thereby increasing the reflectance and reducing the reflection loss.

Although air occupies the interiors of the recesses 160 and 161 in the present embodiment, they may be occupied with a material having a lower refractive index than the core portion 14 instead.

A curved waveguide that bends the optical path in the thickness direction of the core layer 13 may be provided instead of the concave portions 160 and 161 .

-Branch pattern-
The optical waveguide 1 shown in FIG. 3 has the core layer 13 in which the plurality of core portions 14 including the branch structure and the widened portions 141 and 142 are formed as described above. That is, the core layer 13 has a plurality of core portions 14 formed in the branch pattern 19 and widened portions 141 and 142 .

The branch pattern 19 includes a widened portion 141 ( first optical path conversion core portion) having a reflecting portion 16a therein, and a widened portion 141 extending from the widened portion 141 and optically connected to the reflective portion 16a. and a branch line core portion 194 extending from the widened portion 141 and optically connected to the reflecting portion 16a, having a width smaller than that of the widened portion 141 and spaced apart from the main line core portion 193. and a widened portion 142 adjacent to the branch line core portion 194 .

Among them, the widened portion 141 includes the reflecting portion 16a therein, as described above. "Internally provided" refers to a state in which the reflecting portion 16a is included inside the widened portion 141 when the core layer 13 is viewed from above. By providing the reflective portion 16a inside in this way, it is possible to ensure a large area where the material having a higher refractive index than the side clad portion 15 and the clad layers 11 and 12 is exposed in the reflective portion 16a. As a result, it is possible to secure a larger region with a small reflection loss in the reflecting portion 16a.

By forming such a branch pattern 19, the light incident on the reflecting portion 16a is divided into two, and emitted from the main line core portion 193 and the branch line core portion 194, respectively. Therefore, for example, light for communication can be taken out from the main line core portion 193 and light for monitoring can be taken out from the branch line core portion 194 . This monitor light is used for inspecting the quality of the light incident from, for example, the reflecting portion 16a without affecting the communication light. Therefore, the soundness of the light emitting element 31 can be monitored by detecting the light intensity of the monitor light, for example.

Optically connected means a state in which two symmetrically connected portions are connected to each other by the material forming the core portion 14, that is, the material having a relatively high refractive index.

Further, although the linearity of the main wire core portion 193 extending from the widened portion 141 is not particularly limited, it is preferable that the main wire core portion 193 is straight within at least a predetermined length range from the widened portion 141 . Thereby, the incidence efficiency of the light incident on the main line core portion 193 from the reflecting portion 16a can be particularly enhanced. As a result, excessive loss can be suppressed. At this time, the predetermined length is, for example, 50 μm. A portion of the main wire core portion 193 that extends linearly from the widened portion 141 is hereinafter referred to as a reference portion 191 .

Further, when the boundary between the main line core portion 193 and the widened portion 141 is defined as an incident end portion 1931, the center point of the width of the incident end portion 1931 is defined as a light incident point 1931a. Further, the central point of the width of the main line core portion 193 at a position of 50 μm from the incident end portion 1931 is defined as a reference portion output point 1931b. At this time, a straight line connecting the light incident point 1931a and the reference portion outgoing point 1931b is called a virtual straight line VL.

The term "excess loss" as used herein refers to a loss of the light intensity incident on the optical waveguide 1 other than the light intensity emitted from the main line core portion 193 and the branch line core portion 194 .
Here, the branch pattern 19 according to this embodiment satisfies the following three conditions.

[1] The main line core portion 193 and the branch line core portion 194 each extend from the widened portion 141 ( first optical path changing core portion) and are optically connected to the reflecting portion 16a.

[2] The width of the main line core portion 193 and the width of the branch line core portion 194 are each smaller than the width of the widened portion 141 ( first optical path changing core portion).

[3] The main line core portion 193 and the branch line core portion 194 are separated from each other [1] to [3] will be sequentially described below.

[1] The main line core portion 193 and the branch line core portion 194 each extend from the widened portion 141 ( first optical path-changing core portion) and are optically connected to the reflecting portion 16a. As described above, the portion adjacent to the upper end of the core portion 14 in FIG. 3 includes the reflecting portion 16a inside. The main line core portion 193 and the branch line core portion 194 each extend downward in FIG. 3 from the widened portion 141 . Therefore, the widened portion 141 and the main line core portion 193 and the widened portion 141 and the branch line core portion 194 are connected by areas having a high refractive index. Therefore, the reflection portion 16a and the main line core portion 193 and the reflection portion 16a and the branch line core portion 194 are optically connected.

According to such a branch pattern 19, the reflecting portion 16a can be optically connected to both the main line core portion 193 and the branch line core portion 194 while suppressing loss. Therefore, the light incident on the reflecting portion 16a can be efficiently distributed to the main line core portion 193 and the branch line core portion 194, and the optical waveguide 1 with small excess loss can be realized.

[2] The width of the main line core portion 193 and the width of the branch line core portion 194 are each smaller than the width of the widened portion 141 ( first optical path changing core portion). , respectively, are smaller than the width of the widened portion 141 , so that when turned inside out, the width of the widened portion 141 is larger than the width of the main line core portion 193 and the width of the branch line core portion 194 . Therefore, as shown in FIG. 3, the widened portion 141 can be adjacent to both the incident end portion 1931 of the main line core portion 193 and the incident end portion 1943 of the branch line core portion 194 with a margin. Further, along with this, the width of the reflecting portion 16 a provided inside the widened portion 141 can be sufficiently widened, so that the light reflected by the reflecting portion 16 a is reflected by the main line core portion 193 and the branch line core portion 194 . It can be efficiently introduced to both.

The width of the widened portion 141 is preferably 150-500%, more preferably 200-400%, of the width of the incident end portion 1931 . Thereby, the widened portion 141 has a width sufficient to be adjacent to both the main line core portion 193 and the branch line core portion 194 . In particular, since the widened portion 141 is a portion that includes the reflective portion 16a, by setting the width of the widened portion 141 within the above range, the width of the reflective portion 16a can be secured sufficiently wide. As a result, for example, even when the center of the width of the reflecting portion 16a is aligned with the virtual straight line VL, the edge of the width of the reflecting portion 16a can be aligned with the incident end portion 1943 of the branch line core portion 194 . In other words, since the center of the width of the reflecting portion 16a tends to have a relatively high surface accuracy, by aligning this area with the incident end portion 1931 of the main line core portion 193, light with uniform propagation modes can be transmitted to the main line core. It can be incident on the portion 193 . As a result, high-quality optical communication with high transmission efficiency and less occurrence of blunting of pulses can be realized.

On the other hand, since the edge of the width of the reflecting portion 16a tends to have relatively low surface accuracy, the light reflected at the edge of the width of the reflecting portion 16a may include many high-order modes. Therefore, when the light reflected in this region is used as light for communication, there is a problem that the quality of optical communication tends to deteriorate.

On the other hand, there is no particular problem in using the light reflected at the edge of the width of the reflecting portion 16a as the light for monitoring. Therefore, by aligning the end of the width of the reflecting portion 16a with the incident end portion 1943 of the branch line core portion 194, it is possible to effectively utilize the light that could not be utilized conventionally. As a result, the light intensity of the monitor light can be ensured without significantly reducing the light intensity of the communication light.

In addition, the width of the widened portion 141 may exceed the upper limit value. will leave. As a result, excessive loss increases, and it may become difficult to increase the arrangement density of branch patterns 19 .

Further, when the width of the main line core portion 193 and the width of the branch line core portion 194 are each equal to or greater than the width of the widened portion 141 ( first optical path changing core portion), the main line core portion 193 and the branch line core portion 194 from the reflecting portion 16a When introducing light, there is a possibility that the light cannot be introduced to both.

Although the width of the main wire core portion 193 is not particularly limited, it is preferably 20 to 80 μm, more preferably 25 to 75 μm. As a result, when a plurality of branch patterns 19 are arranged in parallel, the density can be increased and the size can be reduced. Also, it is possible to prevent the transmission efficiency from being lowered.

That is, when the width of the main line core portion 193 is less than the lower limit value, the transmission efficiency of the main line core portion 193 may decrease. On the other hand, if the width of the main wire core portions 193 exceeds the upper limit, there is a possibility that the arrangement density of the main wire core portions 193 cannot be sufficiently increased.

The width of the main line core portion 193 refers to the length in the direction orthogonal to the virtual straight line VL.

The width of the main line core portion 193 is preferably 80 to 120%, more preferably 90 to 110%, of the width of the incident end portion 1931 of the main line core portion 193 over its entire length. As a result, the width of the main line core portion 193 is substantially constant as a whole, so that excess loss is small and high-quality optical communication can be realized.

Also, the width of the branch line core portion 194 may be the same as or narrower than the width of the main line core portion 193 , but is preferably wider than the width of the main line core portion 193 . As a result, the light intensity of the monitor light can be sufficiently ensured without reducing the light intensity of the communication light. As a result, the light intensity of the communication light emitted from the main line core portion 193 and the light intensity of the monitor light emitted from the branch line core portion 194 are well balanced.

Specifically, the width of the branch line core portion 194 is preferably more than 100%, more preferably 101 to 200%, and more preferably 110 to 150% of the width of the incident end portion 1931 of the main line core portion 193. It is more preferable to have If the width of the branch line core portion 194 is less than the lower limit value, there is a possibility that the effect of widening the width of the branch line core portion 194 cannot be fully enjoyed. On the other hand, when the width of the branch line core portion 194 exceeds the upper limit value, the width of the branch line core portion 194 becomes excessively wide, so there is a possibility that the arrangement density of the branch patterns 19 cannot be sufficiently increased.

[3] The main line core portion 193 and the branch line core portion 194 are separated from each other The main line core portion 193 and the branch line core portion 194 are separated from each other A state in which the side clad portion 15 is interposed therebetween.

Since the main line core portion 193 and the branch line core portion 194 are separated from each other, leakage of light propagating through the main line core portion 193 to the branch line core portion 194 is suppressed. Thereby, it is possible to suppress the decrease in the light intensity of the light for communication. Further, even when light leaks from the main line core portion 193 to the side clad portion 15 or light enters the side clad portion 15 from the reflection portion 16a, the leaked light can be taken into the branch line core portion 194. . As a result, it is possible to suppress the leakage light from entering the main line core portion 193 and prevent the quality of optical communication from deteriorating. That is, by confining the leaked light in the branch line core portion 194, the influence of the leaked light on optical communication can be minimized.

A distance S between the main line core portion 193 and the branch line core portion 194 is not particularly limited, but is preferably 2 to 30 μm, more preferably 4 to 10 μm. By setting the separation distance S within the above range, the light intensity of light leaking from the main line core portion 193 to the branch line core portion 194 can be minimized while increasing the arrangement density of the branch patterns 19 . As a result, it is possible to achieve both miniaturization of the optical waveguide 1 and high quality of optical communication.

If the separation distance S is less than the lower limit value, the light intensity of light leaking from the main line core portion 193 to the branch line core portion 194 may increase. On the other hand, if the separation distance S exceeds the upper limit value, the light intensity of the light leaking to the side clad portion 15 increases, and there is a possibility that the excess loss increases.

By satisfying the above three conditions, the optical waveguide 1 has a small excess loss and is miniaturized.

Further, the optical module 100 has the optical waveguide 1, the electric substrate 2, and the light emitting element 31 and the light receiving element 32 optically connected to the optical waveguide 1, as described above. In such an optical module 100, light for monitoring is received by the light receiving element 32 in the optical waveguide 1, and while monitoring the light intensity, sufficient light intensity is secured for light for communication, and high quality light is obtained. Communication is enabled. In other words, since the light for communication can be enhanced while securing sufficient light intensity for the light for monitoring, the balance between these can be maintained well, and since the excess loss in the optical waveguide 1 is small, high quality can be achieved. While enabling optical communication, it also has the added value of being able to constantly monitor the soundness of the light emitting element 31 . Also, the optical module 100 can be miniaturized and can be mounted on various electronic devices. Therefore, such an optical module 100 has high reliability.

In addition, the control element 4 monitors the light intensity of the light for monitoring by the light receiving element 32, and, for example, when the light intensity falls below a threshold value, issues a warning or stops driving the light emitting element 31. You may It is also possible to predict the deterioration state of the light-emitting element 31 based on the fluctuation of the light intensity, and to encourage the replacement of the light-emitting element 31 before failure occurs.

Also, the length L1 of the branch line core portion 194 is preferably 800 to 10000 μm, more preferably 900 to 8000 μm, even more preferably 1000 to 7000 μm. By setting the length L1 within the above range, the size of the optical waveguide 1 and the optical module 100 can be reduced. If the length L1 is less than the lower limit, the widened portion 142 provided adjacent to the output end portion 1944 of the branch line core portion 194 must bend the main line core portion 193 and the branch line core portion 194 with a larger curvature. It may be difficult to secure the necessary space for When the optical waveguide 1 is bent with a large curvature, the bending loss increases in the main line core portion 193 and the branch line core portion 194, and the excess loss of the optical waveguide 1 may increase.

The length L1 of the branch line core portion 194 refers to the length of the branch line core portion 194 along the imaginary straight line VL.

Also, the length L2 of the main line core portion 193 may be shorter than the length L1 of the branch line core portion 194, but is preferably longer. This prevents the MT optical connector 62 from interfering with the reflecting portion 16b when the MT optical connector 62 is attached to the output end portion 1932 of the main line core portion 193 .

Although the length L2 is not particularly limited, it is preferably 1000 μm to 100 mm, more preferably 1500 μm to 50 mm. Thereby, the optical waveguide 1 and the optical module 100 can be sufficiently miniaturized.

Further, the branch line core portion 194 shown in FIG. 3 includes a first shape curved portion 1941 and a second shape curved portion 1942 as two portions that bend in different directions.

FIG. 5 is an enlarged view of the branch line core portion 194 shown in FIG. Moreover, FIG. 6 is a diagram schematically emphasizing the second shape curved portion 1942 shown in FIG. 5, and FIG. 7 schematically emphasizing the first shape curved portion 1941 shown in FIG. It is a diagram. 5 to 7, the linear curvature of the branch line core portion 194 is emphasized compared to FIG.

The branch line core portion 194 shown in FIG. 3 includes a second shape curved portion 1942 extending from the widened portion 141 and a first shape curved portion 1941 extending therefrom, as shown emphasized in FIG. I'm in.

Here, a set of center points of the width of the branch line core portion 194 is defined as a branch line central axis C2. At this time, when the branch line core portion 194 shown in FIG. 3 moves away from the widened portion 141 along its extending direction, in a plan view of the core layer 13, as shown in FIG. of the angles formed by the tangents TL21, TL22, TL23 and the imaginary straight line VL, the angles β1, β2, β3 on the acute side gradually increase, and , and a first shape curve portion 1941 that curves so that angles α1, α2, and α3 on the acute side of the angles formed by the tangent lines TL11, TL12, and TL13 of the branch center axis C2 and the imaginary straight line VL gradually decrease. include.

Of these, in the second shape curved portion 1942 shown in FIG. 6, tangent lines TL21, TL22, and TL23 are drawn at three mutually separated points on the branch line central axis C2. The tangent lines TL21, TL22, and TL23 are arranged in this order from the widened portion 141 side. Among the angles formed by the tangent line TL21 and the imaginary straight line VL, the angle on the acute side is defined as β1. When the acute angle is β3, the relationship β1<β2<β3 is satisfied.

By including such a second shape curved portion 1942 , the branch line core portion 194 can be gradually separated from the main line core portion 193 . Thereby, the bending loss in the branch line core portion 194 can be suppressed. In addition, it is possible to secure a space for providing a reflecting portion 16b having a sufficient size as the reflecting portion 16b connecting the output end portion 1944 of the branch line core portion 194. FIG. As a result, it is possible to sufficiently suppress the reflection loss in the reflecting portion 16b.

On the other hand, in the first shape curved portion 1941 shown in FIG. 7, tangent lines TL11, TL12, and TL13 are drawn at three mutually separated points on the branch line central axis C2. The tangent lines TL11, TL12, and TL13 are arranged in this order from the widened portion 141 side. Among the angles formed by the tangent line TL11 and the imaginary straight line VL, the angle on the acute side is α1, the angle formed by the tangent line TL12 and the imaginary line VL on the acute side is α2, and Assuming that the angle on the acute side of the formed angle is α3, the relationship of α1>α2>α3 is satisfied.

By including such a first shape curved portion 1941 , the branch line core portion 194 can be gradually brought closer to the main line core portion 193 . As a result, the width of the branch pattern 19 can be optimized by preventing the distance between the two from becoming too wide.

From the above, by including the first shape curved portion 1941 and the second shape curved portion 1942, it is possible to realize the optical waveguide 1 with small excessive loss by suppressing bending loss and reflection loss while achieving miniaturization. .

It is preferable that the curvatures of the first shape curved portion 1941 and the second shape curved portion 1942 are as small as possible only from the viewpoint of bending loss. That is, the radius of curvature should be as large as possible. However, if the radius of curvature is large, the length L1 must be made very long in order to secure a space for arranging the widened portion 142 . If so, it may become difficult to miniaturize the optical waveguide 1 and the optical module 100 .

Therefore, the radius of curvature of the first curved portion 1941 and the second curved portion 1942 is preferably 0.30 to 5.0 mm, more preferably 0.50 to 3.0 mm. More preferably 0 to 2.5 mm. By setting the radius of curvature within the above range, it is possible to sufficiently reduce the size of the optical waveguide 1 while suppressing the bending loss within the allowable range.

The curvature radii of the first shape curved portion 1941 and the second shape curved portion 1942 are obtained as the curvature radius of the branch line central axis C2.

In addition, branch line core portion 194 may include a linearly extending portion as a portion other than first shape curved portion 1941 and second shape curved portion 1942 .

In addition, in the present embodiment, as shown in FIG. 3, the main wire core portion 193 extends linearly along the imaginary straight line VL. At this time, the maximum distance L3 between the virtual straight line VL and the branch line central axis C2 is preferably 50 to 150 μm, more preferably 75 to 125 μm. Thereby, the width of the branch pattern 19 can be sufficiently narrowed. Therefore, for example, when a plurality of branch patterns 19 are arranged in parallel as shown in FIG. 3, the arrangement density can be easily increased. As a result, it is possible to realize the optical waveguide 1 and the optical module 100 that are both compact and multi-channel.

If the maximum distance L3 is less than the lower limit, the space required for the widened portion 142 cannot be secured, and the width of the recessed portion 161 provided therein is also limited. As a result, there is a risk that the reflection loss associated with the optical path change via the reflecting portion 16b will increase. On the other hand, if the maximum distance L3 exceeds the upper limit value, the arrangement density of the branch patterns 19 is lowered, and it may become difficult to achieve both miniaturization and multi-channel. Further, since it is necessary to increase the curvature in the linear shape of the branch line core portion 194, the light intensity of the light for monitoring may decrease.

Further, when the main line core portion 193 extends linearly, there is no bending loss, so the optical intensity of the light for communication can be substantially maximized. Note that the main wire core portion 193 is not limited to the illustrated shape, and may extend in a curved shape, or may include both a linearly extending portion and a curved portion.

In the branch pattern 19 shown in FIG. 3, both the extension line 193E of the main line core portion 193 and the extension line 194E of the branch line core portion 194 intersect the reflecting portion 16a in plan view of the core layer 13 . That is, an extension line 193E formed by extending the main line core portion 193 toward the widened portion 141 side and an extended line 194E formed by extending the branch line core portion 194 toward the widened portion 141 side are the plane of the core layer 13 shown in FIG. Visually, they overlap with the reflecting portions 16a. Thereby, for example, the light reflected by the reflecting portion 16 a can be efficiently introduced into the main line core portion 193 and the branch line core portion 194 . Also, the widened portion 141 itself can be used as a light branching structure. Therefore, it is possible to obtain the optical waveguide 1 having a small excess loss even if it is small.

It is preferable that the extension line 193E intersects the reflecting portion 16a over its entire width. Thereby, the intensity of the light introduced into the main line core portion 193 can be sufficiently ensured. On the other hand, the extension line 194E may cross the reflecting portion 16a over its entire width, but it is preferable that a part of its width crosses the reflecting portion 16a. As a result, the necessary and sufficient intensity of light introduced into the branch line core portion 194 can be ensured, and the amount of light that is wasted even if reflected by the reflecting portion 16a can be reduced. As a result, an optical waveguide 1 with small excess loss is obtained.

Note that the extension lines 193E and 194E do not necessarily have to be arranged as described above depending on the inclination angle of the reflecting portion 16a. Further, the extension lines 193E and 194E are hatched in FIG.

Further, the core layer 13 according to this embodiment includes a plurality of branch patterns 19 arranged along the direction intersecting the virtual straight line VL. As a result, a plurality of mutually independent optical signals can be simultaneously input to each branch pattern 19, so that, for example, multi-channel optical fibers can be connected, enabling large-capacity optical communication. . Although the number of branch patterns 19 formed in the core layer 13 is not particularly limited, it is preferably about 1 to 100. If the number of branch patterns 19 is large, the optical waveguide 1 may be multi-layered as necessary. More specifically, a multilayer structure can be formed by alternately stacking core layers and clad layers on the clad layer 12 shown in FIG.

The distance between the adjacent branch patterns 19, that is, the distance L4 between the virtual straight lines VL of the adjacent branch patterns 19 shown in FIG. is more preferable. Thereby, the arrangement density of the branch patterns 19 can be sufficiently increased while avoiding interference between the branch patterns 19 . As a result, it is possible to achieve both miniaturization and multi-channeling of the optical waveguide 1 . Therefore, it is possible to prevent deterioration in the detection accuracy of the light intensity of the monitor light and deterioration in the quality of optical communication.

Further, when the light intensity emitted from the main line core portion 193 is defined as the main line output intensity, and the light intensity emitted from the branch line core portion 194 is defined as the branch line output intensity, the ratio of the branch line output intensity to the main line output intensity (branch ratio) is − It is preferably 25 dB or more, more preferably -20 to -10 dB. With such a branching ratio, the light intensity of the communication light emitted from the main line core portion 193 and the light intensity of the monitor light emitted from the branch line core portion 194 are particularly well balanced. In other words, the light intensity of the monitor light can be sufficiently ensured without remarkably degrading the quality of optical communication. As a result, it is possible to continue to monitor the soundness of the light emitting element 31 more accurately while performing good optical communication.

<Electronic equipment>
According to the optical waveguide of the present invention as described above, as described above, the light intensity of the monitor light can be monitored, and the light intensity of the communication light can be sufficiently secured. Therefore, the function of monitoring the soundness of the light emitting element 31 can be easily imparted to the electronic device. Moreover, since the optical waveguide 1 has a small excess loss and is miniaturized, high-quality optical communication is possible, and miniaturization of electronic equipment is facilitated. Therefore, by providing the optical waveguide of the present invention, a highly reliable electronic device (the electronic device of the present invention) can be obtained.

Examples of the electronic device of the present invention include electronic devices such as smart phones, tablet terminals, mobile phones, game machines, router devices, WDM devices, personal computers, televisions, servers, and supercomputers.

Although the optical waveguide, optical module, and electronic device of the present invention have been described above based on the illustrated embodiments, the present invention is not limited to these.

For example, in the above embodiments, a lens is arranged between the optical waveguide and the light emitting/receiving element, but this lens may be provided as required and may be omitted. Also, the housing of the optical module may be omitted.

Also, the shape of the optical connector included in the optical module is not particularly limited, and may be any shape. Also, the optical connector may be provided as necessary, for example, the optical waveguide and the optical fiber may be directly connected, or the optical connector may be connected to the optical fiber via a reflector provided in the optical waveguide. .

Moreover, as the electric substrate, a resin substrate such as a rigid substrate or a flexible substrate is often used, but a ceramic substrate, a glass substrate, or the like may also be used.

1 Optical waveguide 2 Electric substrate 4 Control element 5 Lens array 7 Case 10 Laminate 11 Cladding layer 12 Cladding layer 13 Core layer 14 Core portion 15 Side clad portion 16a Reflecting portion 16b Reflecting portion 17 Lower protective layer 18 Upper protective layer 19 Branch pattern 21 Insulating substrate 22 Conductive layer 23 Contact 31 Light emitting element 32 Light receiving element 51 Bottom 52 Wall 53 Cavity 54 Lens 61 Receptacle 62 MT optical connector 81 Electrical wiring 82 Electrical connector 91 Optical fiber 92 MPO optical connector 100 Optical module 141 Widening Part 142 Widened part 160 Recessed part 161 Recessed part 191 Reference part 193 Main line core part 193E Extension line 194 Branch line core part 194E Extension line 611 MT type receiving part 612 MPO type receiving part 1931 Incidence end 1931a Light incidence point 1931b Reference part emission point 1932 Output End 1941 First shape curved portion 1942 Second shape curved portion 1943 Incident end 1944 Output end C2 Branch line central axis L3 Maximum distance L4 Distance P1 Optical path P2 Optical path S Spacing distance TL11 Tangent line TL12 Tangent line TL13 Tangent line TL21 Tangent line TL22 Tangent line TL23 Tangent line VL virtual straight line

Claims (9)

a first optical path-changing core portion having a first reflecting portion inside;
a main line core portion extending from the first optical path-changing core portion and optically connected to the first reflecting portion and having a width smaller than both the first optical path-changing core portion and the first reflecting portion;
Extending from the first optical path-changing core portion and optically connected to the first reflecting portion, having a smaller width than both the first optical path-changing core portion and the first reflecting portion, and the main line core a branch line core portion spaced apart from the portion;
a second optical path changing core portion having a second reflecting portion inside;
having a core layer formed with a branched pattern comprising
The length of the main line core portion is longer than the length of the branch line core portion,
In a plan view of the core layer, the branch pattern is such that the entire width of the extension line of the main line core portion and part of the width of the extension line of the branch line core portion intersect the first reflecting portion. is formed and
Light from the light-emitting element enters the main line core portion and the branch line core portion through the first reflecting portion, and light from the branch line core portion enters the light receiving element through the second reflecting portion. An optical waveguide characterized by being used as follows. 2. The optical waveguide according to claim 1, wherein the main line core portion has a width of 20 to 80 μm. 3. The optical waveguide according to claim 1, wherein the main material of said core layer is a resin material. 4. The optical waveguide according to any one of claims 1 to 3, wherein the branch line core portion has a length of 800 to 10000 µm. A straight line connecting a center point of the width of the main line core portion at the boundary with the optical path-changing core portion and a center point of the width at a position 50 μm from the optical path-changing core portion is defined as a virtual straight line,
When the aggregate of the center points of the width of the branch line core portion is defined as the branch line central axis,
When the branch line core portion moves away from the optical path changing core portion along its extending direction, the acute angle side of the angle formed by the tangent to the central axis of the branch line and the imaginary straight line in plan view of the core layer is A first curved portion that gradually decreases in size, and a second curved portion that gradually increases in angle formed by a tangent to the central axis of the branch line and the imaginary straight line in a plan view of the core layer. 5. The optical waveguide according to any one of claims 1 to 4, comprising a two-shaped curved portion. A first recess and a second recess penetrating the core layer in the thickness direction ,
The first reflecting portion is a part of the inner surface of the first concave portion,
The optical waveguide according to any one of claims 1 to 5, wherein the second reflecting portion is part of the inner surface of the second concave portion. 7. The optical waveguide according to any one of claims 1 to 6, wherein the core layer has a plurality of branch patterns arranged along a direction crossing the extending direction of the main line core portion. an optical waveguide according to any one of claims 1 to 7;
a light emitting element optically connected to the reflecting section;
a light receiving element optically connected to the branch line core portion;
An optical module characterized by comprising: An electronic device comprising the optical waveguide according to any one of claims 1 to 7.

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