JP2010281988A - Optical module and optical waveguide structure - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To achieve two-way communication to increase the number of channels without increasing the number of optical fibers to be connected to an optical waveguide structure, and to reduce a loss upon optically connecting an optical fiber to a light receiving element and a light emitting element. <P>SOLUTION: An optical module 5 is provided, including an optical waveguide structure 4 having a curved optical waveguide 3 that optically connects an optical fiber 10 to a light receiving element 1 and a light emitting element 2. The curved optical waveguide 3 has a waveguide core 6 having a tapered form in the width or thickness, which increases toward an end face 6A where the waveguide is connected to the light receiving element 1 and the light emitting element 2. The optical module is provided with: the light receiving element 1 optically connected to the outer portion of the waveguide core 6; and the light emitting element 2 optically connected to the inner portion of the waveguide core 6. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an optical module and an optical waveguide structure used for optical communication, for example.

In recent years, development of multi-channel optical transceivers (for example, wavelength division multi-channel optical transceivers) including surface optical elements such as surface-emitting lasers (light-emitting elements) and photodiodes (photo-detectors; light-receiving elements) has been underway.
For example, when using a surface optical device such as a surface emitting laser or a photodiode in an optical module such as a multi-channel optical transceiver, the light incident surface (light receiving surface) or light emitting surface (light emitting surface) of the surface optical device is mounted. Parallel to the substrate. For this reason, light is incident or emitted perpendicularly to the mounting substrate.

On the other hand, it is necessary to reduce the size and thickness of such an optical module.
In order to reduce the size and thickness, it is desirable to arrange the optical fiber (optical fiber array) in parallel with the mounting substrate. In this case, the end face of the optical fiber and the light incident surface or light emitting surface of the surface optical element are in a substantially right-angle positional relationship.
For this reason, the optical fiber array and the surface light are bent by approximately 90 degrees of the light path (optical path) incident or emitted perpendicular to the light incident surface or the light emitting surface of the surface optical element mounted on the substrate. It is necessary to optically connect the element.

Therefore, in order to sharply bend the light path in a narrow space in an apparatus such as an optical transceiver, for example, an optical waveguide structure having an optical waveguide (curved optical waveguide) on a substantially perpendicular curved surface is used. On the other hand, there is a technique in which light incident or emitted is guided along a curved surface and coupled to an optical fiber array (first technique).
In such an optical waveguide structure, a liquid core material is dropped into a narrow groove formed in advance on a curved surface, a film is pasted thereon, and a soft material such as silicon rubber is used and pressed with a certain pressure. It is manufactured by thinly extending the liquid core material by applying and curing it by ultraviolet irradiation.

Also, curved optical waveguides are provided on both the front and back surfaces of the optical waveguide structure, the light receiving element and the optical fiber are connected by the curved optical waveguide on one side, and the light emitting element and the optical fiber are connected by the curved optical waveguide on the other side. There is also a technique as described above (second technique).
In addition, in order to enable two-way communication with a single optical fiber, a transmission light linear waveguide connected to the light emitting element at a position facing the core region of the single optical fiber, and a light receiving element. There is also a technique of separately providing a linear waveguide for received light to be connected (third technique).

JP 2005-115346 A JP 2006-91684 A JP-A-11-308179

By the way, when the number of channels is increased in the first technique described above to increase the number of channels, it is conceivable to provide curved optical waveguides on both the front and back surfaces of the optical waveguide structure, for example, as in the second technique described above.
However, when the curved optical waveguides are provided on both the front and back surfaces of the optical waveguide structure as in the second technique described above, the number of optical fibers increases as the number of channels increases, and the optical fiber wiring space increases. Will end up. This also applies to an optical waveguide structure having a curved optical waveguide on a plane.

In this case, it is conceivable to perform bidirectional communication using a single optical fiber as in the third technique described above.
However, in the third technique described above, the transmission light linear waveguide and the reception light linear waveguide are separately provided at positions facing the core region of one optical fiber. Leaks without being coupled to the received light waveguide, resulting in a large loss.

  Therefore, bidirectional communication is performed to increase the number of channels without increasing the number of optical fibers connected to the optical waveguide structure. In this case, one optical fiber, a light receiving element, and a light emitting element I want to reduce the loss when I connect the optically.

  Therefore, the optical module includes an optical waveguide structure having a curved optical waveguide that optically connects the optical fiber, the light receiving element, and the light emitting element, and the curved optical waveguide is connected to the light receiving element and the light emitting element. A light receiving element optically connected to the outer part of the waveguide core and optically connected to the inner part of the waveguide core. It is necessary to provide a light emitting element that has been manufactured.

  The optical waveguide structure includes a curved optical waveguide that optically connects an optical fiber, a light receiving element, and a light emitting element, and the curved optical waveguide has a width or a width toward an end face on a side connected to the light receiving element and the light emitting element. A waveguide core having a thickness that increases in a tapered shape; a first lens or a first mirror that guides light emitted from an outer portion of the waveguide core to the light receiving element; and light emitted from the light emitting element. It is a requirement to include a second lens or a second mirror that leads to the inner part of the core.

  Therefore, according to the present optical module and the optical waveguide structure, since bidirectional communication is performed, there is an advantage that the number of channels can be increased without increasing the number of optical fibers connected to the optical waveguide structure. . In addition, when bidirectional communication is performed, there is an advantage that loss when optically connecting one optical fiber, a light receiving element, and a light emitting element can be reduced.

It is typical sectional drawing which shows the structure of the optical module and optical waveguide structure concerning 1st Embodiment. It is a typical sectional view showing composition of the 1st modification of an optical module concerning a 1st embodiment, and an optical waveguide structure. It is typical sectional drawing which shows the structure of the 2nd modification of the optical module concerning 1st Embodiment, and an optical waveguide structure. It is typical sectional drawing which shows the structure of the 3rd modification of the optical module concerning 1st Embodiment, and an optical waveguide structure. It is a typical perspective view which shows the structure of the 4th modification of the optical module and optical waveguide structure concerning 1st Embodiment. It is a typical perspective view which shows the structure of the optical module and optical waveguide structure concerning 2nd Embodiment. It is a schematic diagram which shows the specific structural example of the optical waveguide structure concerning 2nd Embodiment. It is a typical perspective view which shows the structure of the modification of the optical module concerning 2nd Embodiment. 1 is a schematic cross-sectional view showing a configuration of a sample of an optical waveguide structure according to Example 1. FIG. 6 is a schematic cross-sectional view for explaining a method for producing a sample of an optical waveguide structure according to Example 1. FIG. 6 is a schematic cross-sectional view showing a configuration of a sample of an optical waveguide structure according to Example 2. FIG.

Hereinafter, the optical module and the optical waveguide structure according to the present embodiment will be described with reference to the drawings.
[First Embodiment]
The optical module and the optical waveguide structure according to the first embodiment will be described with reference to FIG.

The optical module according to the present embodiment, for example, converts an input electrical signal into an optical signal and transmits the optical signal via an optical fiber (optical transmitter), and electrically converts the optical signal input via the optical fiber. An optical transceiver having a function (optical receiver) for converting into a signal and receiving the signal.
As shown in FIG. 1, the present optical module includes a surface light-receiving element (surface-type optical element) 1 having an incident surface (light-receiving surface) on the surface and a surface light-emitting element (surface-emitting element) having an emission surface (light-emitting surface) on the surface. A planar optical element) 2 and an optical waveguide structure 4 having an optical waveguide (curved optical waveguide) 3 on a curved surface in order to sharply bend the light path. That is, the optical module 5 is formed by mounting the surface light-receiving element 1, the surface light-emitting element 2, and the optical waveguide structure 3 on a printed board (circuit board) (not shown).

In FIG. 1, one optical module 5 (including the surface light receiving element 1, the surface light emitting element 2, and the optical waveguide structure 4) and another optical module 5A (the surface light receiving element 1, the surface light emitting element). 2, including an optical waveguide structure 4).
Here, the surface light-receiving element 1 is a photodiode (PD: Photo detector).

The surface light emitting element 2 is a surface emitting laser (VCSEL (Vertical-Cavity Surface-Emitting Laser)).
The optical waveguide structure 4 is a curved optical waveguide component (for example, a polymer optical waveguide whose main material is a polymer) formed so that light propagates in the curved waveguide core 6.
Here, as shown in FIG. 1, the optical waveguide structure 4 includes a clad structure 8 (lower clad) having a groove 7 formed on a curved surface, a waveguide core 6 formed in the groove 7, and a waveguide. And a clad film 9 (upper clad) covering the waveguide core 6.

Specifically, as shown in FIG. 1, the clad structure 8 has a groove 7 (curved groove; waveguide groove; narrow groove) extending from one end to the other end of the curved surface on the curved surface of the structure surface. Is a curved surface structure.
Here, the clad structure 8 is a transparent structure formed of a transparent member made of a transparent clad material, and has a refractive index n1. For example, a molded product (resin molded product) using an olefin polymer (for example, polyolefin).

  As shown in FIG. 1, the waveguide core 6 is formed by embedding a groove 7 formed in a curved surface layer portion of the cladding structure 8 with a transparent core material. For this reason, the waveguide core 6 is formed in a curved shape along the curved surface of the cladding structure 8. The waveguide core 6 has a refractive index n2 larger than the refractive index n1 of the cladding structure 8 (n2> n1). In this embodiment, since the waveguide core 6 is formed by applying a liquid core material (liquid adhesive) and curing it, a material having a refractive index n2 after curing (a refractive index of n2). A transparent solid).

As shown in FIG. 1, the clad film 9 is laminated so as to cover the waveguide core 6 formed in the groove 7 on the curved surface of the clad structure 8. The clad film 9 has a refractive index n3 smaller than the refractive index n2 of the waveguide core 6 (n3 <n2).
In particular, in the present embodiment, as shown in FIG. 1, the waveguide core 6 of the curved optical waveguide 3 has a thickness toward the end face 6 </ b> A on the side connected to the surface light-receiving element 1 and the surface light-emitting element 2. The taper is thick.

  Specifically, the waveguide core 6 of the curved optical waveguide 3 has a first region in which the thickness increases in a tapered shape toward the end face 6A on the side connected to the surface light-receiving element 1 and the surface light-emitting element 2. A linear region) and a second region (arc-shaped region) that is continuous with the first region and has a constant width and thickness. Here, the waveguide core 6 is formed by embedding the groove 7 formed in the cladding structure 8 with a core material. For this reason, in the first region, the depth of the groove 7 is tapered toward the end face 6A on the side connected to the surface light-receiving element 1 and the surface light-emitting element 2. In the second region, the width and depth of the groove 7 are constant.

  In the present embodiment, as shown in FIG. 1, the waveguide core 6 of the curved optical waveguide 3 includes two end faces 6A connected to the surface light-receiving element 1 and the surface light-emitting element 2 at different angles. It consists of surfaces 6a and 6b. That is, the end surface of the outer portion of the waveguide core 6 of the curved optical waveguide 3 is a first inclined surface 6a that is inclined at a first angle. The light guided in a distributed manner is emitted toward the light receiving element 1. On the other hand, the end surface of the inner portion of the waveguide core 6 of the curved optical waveguide 3 is a second inclined surface 6b that is inclined at a second angle. It is made to enter (photocouple) the part. The outer portion of the waveguide core 6 refers to the radially outer portion of the arc-shaped portion of the waveguide core 6 and the portion connected thereto, and the inner portion of the waveguide core 6 refers to the circle of the waveguide core 6. It refers to the radially inner part of the arc-shaped part and the part connected thereto.

  In the present embodiment, the optical waveguide structure 4 includes the first lens 11 that guides the light emitted from the outer portion of the first region of the waveguide core 6 of the curved optical waveguide 3 to the surface light receiving element 1, and the surface. And a second lens 12 that guides light emitted from the light emitting element 2 to the inner portion of the first region of the waveguide core 6 of the curved optical waveguide 3. Here, the first lens 11 is provided between the outer portion of the first region of the waveguide core 6 of the curved optical waveguide 3 and the surface light receiving element 1, and the first lens 11 of the waveguide core 6 of the curved optical waveguide 3 is provided. A second lens 12 is provided between the inner portion of one region and the surface light emitting element 2. The first lens 11 and the second lens 12 are formed so as to be aligned in the thickness direction of the waveguide core 6 of the curved optical waveguide 3. Further, the first lens 11 and the second lens 12 are integrally formed with the optical waveguide structure 4.

  In the present embodiment, the surface light-receiving element 1 is optically connected to the outer portion of the first region of the waveguide core 6 of the curved optical waveguide 3. In addition, the surface light emitting element 2 is optically connected to an inner portion of the first region of the waveguide core 6 of the curved optical waveguide 3. Here, the surface light-receiving element 1 and the surface light-emitting element 2 are arranged on a substrate (not shown) so as to be aligned in the thickness direction of the waveguide core 6 of the curved optical waveguide 3 (depth direction of the groove 7). ing.

  That is, in this embodiment, one surface light receiving element 1 and one surface type are provided on one end surface (lower end surface in FIG. 1) of one curved optical waveguide 3 provided in the optical waveguide structure 4. The light emitting element 2 is optically connected via the first lens 11 and the second lens 12. Further, one optical fiber 10 is provided on the other end face orthogonal to the one end face (the right end face of the left optical waveguide structure 4 and the left end face of the right optical waveguide structure 4 in FIG. 1). Are optically connected via the third lens 13. In this way, one optical fiber 10 and one light receiving element 1 and one light emitting element 2 are optically connected by one curved optical waveguide 3.

  Therefore, the light emitted from the surface light emitting element 2 is guided through the curved optical waveguide 3 and coupled to the optical fiber 10, and the light incident from the optical fiber 10 is also guided through the same curved optical waveguide 3. Then, it is coupled to the surface light receiving element 1. That is, the curved optical waveguide 3 functions as a reception-side optical waveguide (reception channel) that connects the optical fiber 10 and the light-receiving element 1, and also transmits a transmission-side optical waveguide (transmission channel) that connects the optical fiber 10 and the light-emitting element 2. ).

  Thus, in the present embodiment, bidirectional communication is possible by one curved optical waveguide 3 and one optical fiber 10. As a result, the number of channels can be substantially doubled without increasing the number of optical fibers 10 connected to the optical waveguide structure 4, leading to a reduction in wiring space. In addition, since it is configured as described above, it is possible to reduce loss when optically connecting one optical fiber 10 to one light receiving element 1 and one light emitting element 2 when performing bidirectional communication. can do.

With the above-described configuration, bidirectional communication becomes possible and loss can be reduced for the following reason.
First, since one optical fiber 10 and one light receiving element 1 and one light emitting element 2 are optically connected by the curved optical waveguide 3, the light from the optical fiber 10 is curved at the curved portion of the curved optical waveguide 3. It is distributed outside (outside in the radial direction of the 1/4 arc). Therefore, the light receiving element 1 is disposed at a position facing (relatively) the outer portion of the waveguide core 6 of the curved optical waveguide 3, and the light emitting element 2 is disposed at a position facing (relatively) the inner portion of the waveguide core 6. is doing. In this way, in consideration of the phenomenon that light tends to be moved outward at the bent portion in the curved optical waveguide 3, the light receiving element 1 is arranged at a position on the extended line of the outer portion of the waveguide core 6 of the curved optical waveguide 3, The light emitting element 2 is arranged at a position on the extension line of the inner portion of the waveguide core 6. Thereby, the light distributed in the outer part of the waveguide core 6 of the curved optical waveguide 3 can be received by the light receiving element 1 with low loss.

  Further, the end of the waveguide core 6 of the curved optical waveguide 3 (the end on the light receiving element 1 and the light emitting element 2 side; the end) is widened in the direction in which the light receiving element 1 and the light emitting element 2 are arranged. Thus, the light emitted from the outer portion of the waveguide core 6 of the curved optical waveguide 3 can be received by the light receiving element 1 with low loss, and the light from the light emitting element 2 can be received by the waveguide core of the curved optical waveguide 3. 6 can be incident on the inner part of the lens 6 with low loss. Further, the light emission distributed in the outer portion of the waveguide core 6 of the curved optical waveguide 3 and arranged so that the light emitted from the curved optical waveguide 3 is arranged in the thickness direction of the waveguide core 6 of the curved optical waveguide 3. The leakage to the element 2 side is prevented.

  The end face 6A of the curved optical waveguide 3 on the side connected to the surface light receiving element 1 and the surface light emitting element 2 of the waveguide core 6 is composed of two surfaces 6a and 6b having different angles. That is, the light guided to the outer portion of the waveguide core 6 of the curved optical waveguide 3 by the first inclined surface 6 a of the outer portion of the waveguide core 6 of the curved optical waveguide 3 is emitted toward the light receiving element 1. The light from the light emitting element 2 is incident on the inner portion of the waveguide core 6 by the second inclined surface 6 b of the inner portion of the waveguide core 6 of the curved optical waveguide 3. Thereby, the light distributed from the outer side of the waveguide core 6 of the curved optical waveguide 3 is arranged so that the light emitted from the curved optical waveguide 3 is arranged in the thickness direction of the waveguide core 6 of the curved optical waveguide 3. The leakage to the light emitting element 2 side is prevented.

In this way, using the light beam separating function of the curved optical waveguide 3 (the function of separating the light from the light emitting element 2 and the light from the optical fiber 10 at the curved portion), the single optical waveguide 3 and the single optical waveguide 3 are separated. Bidirectional communication using one optical fiber 10 is possible.
Therefore, according to the optical waveguide structure and the optical module according to the present embodiment, the number of channels can be increased without increasing the number of optical fibers 10 connected to the optical waveguide structure 4 in order to perform bidirectional communication. There is an advantage that can be. In addition, when performing bidirectional communication, there is also an advantage that loss when optically connecting one optical fiber 10 to the light receiving element 1 and the light emitting element 2 can be reduced.

The present invention is not limited to the configuration described in the first embodiment described above, and various modifications can be made without departing from the spirit of the present invention.
For example, in the first embodiment described above, the waveguide core 6 of the curved optical waveguide 3 has two surfaces 6a and 6b whose end surfaces 6A on the side connected to the surface light receiving element 1 and the surface light emitting element 2 have different angles. However, it is not limited to this. For example, as shown in FIG. 2, in the waveguide core 6 of the curved optical waveguide 3, the end face 6 </ b> B on the side connected to the surface light-receiving element 1 and the surface light-emitting element 2 may be a flat surface (vertical surface). In FIG. 2, the same components as those in the first embodiment (see FIG. 1) are denoted by the same reference numerals.

In the first embodiment described above, the light receiving element 1 and the light emitting element 2 are arranged side by side at a position facing one end face of the optical waveguide structure 4, but the present invention is not limited to this.
For example, as shown in FIGS. 3 and 4, the light-emitting element 2 is disposed at a position facing one end face (the lower end face in FIGS. 3 and 4) of the optical waveguide structure 4, and the other end face (FIG. 3). 3. In FIG. 4, the light receiving element 1 may be arranged at a position facing the left end face of the left optical waveguide structure 4 and the right end face of the right optical waveguide structure 4).

  In this case, for example, as shown in FIG. 3, the angle of the first inclined surface 6d, which is the outer portion of the end face 6C of the waveguide core 6 of the curved optical waveguide 3, is set to the outer portion of the waveguide core 6 of the curved optical waveguide 3. The angle may be such that the guided light is totally reflected. In this case, since there are fewer restrictions on the arrangement of the light emitting elements 2 than in the case of the first embodiment described above, the angle of the second inclined surface 6e, which is the inner portion of the end surface 6C of the waveguide core 6 of the curved optical waveguide 3, is increased. There are fewer restrictions.

For example, as shown in FIG. 4, the angle of the first inclined surface 6f, which is the outer portion of the end surface 6D of the waveguide core 6 of the curved optical waveguide 3, and the refractive index difference between both sides across the first inclined surface 6f [ The refractive index difference between the refractive index n _{1 of the} core and the refractive index n _{2 of the} cladding (n ₁ > n ₂ )] is the light guided to the outer portion of the waveguide core 6 of the curved optical waveguide 3. You may set so that it may totally reflect. In this case, since there are fewer restrictions on the arrangement of the light emitting elements 2 than in the case of the first embodiment described above, the angle of the second inclined surface 6g, which is the inner portion of the end surface 6D of the waveguide core 6 of the curved optical waveguide 3, is increased. There are fewer restrictions.

  For example, as shown in FIGS. 3 and 4, the first lens 11 provided between the outer portion of the waveguide core 6 of the curved optical waveguide 3 and the surface light receiving element 1 is not limited to the optical waveguide structure 4. 3 (FIG. 3 and FIG. 4, the left end surface of the left optical waveguide structure 4 and the right end surface of the right optical waveguide structure 4). On the other hand, the second lens 12 provided between the inner portion of the waveguide core 6 of the curved optical waveguide 3 and the surface light emitting element 2 is one end surface of the optical waveguide structure 4 (in FIG. 3 and FIG. Side end face).

  Accordingly, the first inclined surfaces 6d and 6f, which are the outer portions of the end faces 6C and 6D of the waveguide core 6 of the curved optical waveguide 3, are distributed and guided to the outer portion of the waveguide core 6 of the curved optical waveguide 3. The reflected light is totally reflected. The first lens provided on the other end surface of the optical waveguide structure 4 (the left end surface of the left optical waveguide structure 4 and the right end surface of the right optical waveguide structure 4 in FIGS. 3 and 4). 11 is emitted toward the light receiving element 1 disposed at a position facing the other end face.

In the above-described embodiment, the optical waveguide structure 4 is provided with one curved optical waveguide 3, and one curved optical waveguide 3 allows one optical fiber 10, one light receiving element 1, and one light emitting element 2. Are described as an example, but the present invention is not limited to this.
For example, as shown in FIG. 5, a plurality of curved optical waveguides 3 and a plurality of optical fibers 10 are used, and bidirectional communication is performed by each curved optical waveguide 3 and each optical fiber 10, thereby realizing multi-channel. You can also

In this case, an optical waveguide structure 4A including a plurality of curved optical waveguides 3, an optical fiber array 10A including a plurality of optical fibers 10, a light receiving element array (array-shaped light receiving element) 1A including a plurality of light receiving elements 1, and a plurality of light emitting elements. A light emitting element array (array light emitting element) 2A including the elements 2 is used.
Specifically, it may be configured as follows.

For example, as shown in FIG. 5, an optical module 5X includes an optical waveguide structure 4A having a plurality of (here, four) curved optical waveguides 3 on a curved surface, a surface light receiving element array 1A, and a surface light emitting element array. 2A is a multi-channel optical transceiver.
Here, the surface light-receiving element array 1A includes a plurality (four in this case) of surface light-receiving elements 1 each having a light-receiving surface on the surface. Here, the surface light-receiving element array 1 </ b> A is a PD array chip including a plurality of photodiodes 1.

The surface light emitting element array 2A includes a plurality of (here, four) surface light emitting elements 2 each having an emission surface on the surface. Here, it is a VCSEL array chip including a plurality of surface emitting lasers 2.
The optical waveguide structure 4A is the same as that of the above-described first embodiment or modification (for example, see FIGS. 1 to 4) except that a plurality of grooves, waveguide cores, curved optical waveguides, and lenses are provided. That is, the optical waveguide structure 4A is formed on a curved surface, and includes a clad structure (lower clad) 8 having a plurality of grooves 7, a waveguide core 6 formed in each groove 7, and a plurality of waveguide cores 6 And a clad film (upper clad) 9 is provided.

Here, the clad structure 8 is configured as a curved structure having a plurality of grooves 7 provided in parallel and extending from one end of the curved surface to the other end on the curved surface of the structure surface.
The plurality of waveguide cores 6 are formed by embedding each groove 7 formed in the curved surface layer portion of the cladding structure 8 with a transparent core material.
The clad film 9 is laminated so as to cover the waveguide core 6 formed in each groove 7 on the curved surface of the clad structure 8.

  In this case, each curved optical waveguide 3 of the optical waveguide structure 4A functions as a reception-side optical waveguide (reception channel) that connects the optical fiber 10 included in the optical fiber array 10A and the light receiving element 1, and an optical fiber array. It also functions as a transmission-side optical waveguide (transmission channel) that connects the optical fiber 10 and the light emitting element 2 included in 10A. Here, a plurality of curved optical waveguides 3 performing bidirectional communication are provided in parallel.

  The optical waveguide structure 4A includes a first lens array 11A including a plurality of the first lenses 11 of the first embodiment described above, and a second lens array 12A including a plurality of the second lenses 12 of the first embodiment described above. And a third lens array 13A including a plurality of the third lenses 13 of the first embodiment described above. That is, each of the plurality of first lenses 11, the plurality of second lenses 12, and the plurality of third lenses 13 is arranged along the direction in which the plurality of curved optical waveguides 3 provided in the optical waveguide structure 4A are arranged. ing.

  The optical waveguide structure 4A is mounted on the printed circuit board 14 through one end face, and on the one end face, the surface light-receiving element array 1A and the surface light-emitting element array 2A are provided with the first lens array. 11A and the second lens array 12A are optically connected. That is, the surface light-receiving element array 1A and the surface light-emitting element array 2A are arranged in parallel along the direction in which the plurality of curved optical waveguides 3 provided in the optical waveguide structure 4A are arranged, and the first lens array 11A and the first lens array 11A Optically connected via the two-lens array 12A. An optical fiber array 10A composed of a plurality (four in this case) of optical fibers 10 having the same fiber diameter is provided on the other end surface orthogonal to one end surface of the optical waveguide structure 4A. Optically connected via Here, the optical fiber array 10A is a ribbon fiber. Here, an optical fiber array 10A with an optical connector is used.

The details of the other configurations are the same as those in the case of the above-described first embodiment or modification (see, for example, FIGS. 1 to 4).
As described above, the optical waveguide structure 4A is used as a multi-channel optical waveguide adapter for connecting the surface light-emitting element array 2A and the surface light-receiving element array 1A to the optical fiber array 10A in a multi-channel optical transceiver that performs bidirectional communication. It is done.
[Second Embodiment]
An optical module and an optical waveguide structure according to the second embodiment will be described with reference to FIGS.

In the present embodiment, a configuration of an optical waveguide structure including a curved optical waveguide, and a bidirectional configuration using a plurality of curved optical waveguides and a plurality of optical fibers, compared to the above-described first embodiment (see FIG. 1). It is different in that multi-channeling is realized by performing communication.
That is, in the first embodiment described above, an optical waveguide structure having a curved optical waveguide formed on a curved surface (the plane on which the optical waveguide is formed is a curved surface along the traveling direction of the optical waveguide). Is used.

In the first embodiment described above, the optical waveguide structure is provided with one curved optical waveguide, and one optical fiber, one light receiving element, and one light emitting element are optically connected by one curved optical waveguide. Is connected to the two-way communication.
On the other hand, in this embodiment, as shown in FIG. 6, an optical waveguide structure 20 having a curved optical waveguide (bending waveguide) 21 formed on a plane is used. In FIG. 6, the same components as those in the first embodiment and the modified example (for example, see FIGS. 1 and 5) are denoted by the same reference numerals.

In particular, in the present embodiment, as shown in FIG. 6, the optical waveguide structure 20 is provided with a plurality (here, four) of curved optical waveguides 21, and the waveguide core 24 of each curved optical waveguide 21 is disposed on the surface. The width is increased in a tapered shape toward the end face 24A on the side connected to the type light receiving element 1 and the surface type light emitting element 2.
In the present embodiment, the length of the inner portion is made longer than the outer portion of the waveguide core 24 of the curved optical waveguide 21. That is, the waveguide core 24 of the curved optical waveguide 21 is a first region (arc-shaped region) whose width increases in a tapered shape toward the end surface 24A on the side connected to the surface light-receiving element 1 and the surface light-emitting element 2. And a second region (straight region) having a constant width and thickness, connected to the inner portion of the first region.

In this way, the end face position of the curved optical waveguide 21 on the side connected to the light receiving element 1 and the light emitting element 2 of the waveguide core 24 is shifted between the outer part and the inner part of the waveguide core 24.
This is to secure an installation space for the light receiving element array 1A and the light emitting element array 2A that are optically connected to the optical waveguide structure 20.
The outer portion of the waveguide core 24 refers to the radially outer portion of the arc-shaped portion of the waveguide core 24, and the inner portion of the waveguide core 24 refers to the radial direction of the arc-shaped portion of the waveguide core 24. The inner part of

In this embodiment, the optical waveguide structure 20 includes mirrors 26 </ b> A and 26 </ b> B on the end face 24 </ b> A on the side connected to the light receiving element 1 and the light emitting element 2 of the waveguide core 24 of the curved optical waveguide 21. Here, the end face 24A of the waveguide core 24 is cut at 45 degrees to form mirrors (45-degree cut mirrors) 26A and 26B.
Specifically, the optical waveguide structure 20 includes a first mirror 26A on the outer portion 24a of the end face 24A of the waveguide core 24 of the curved optical waveguide 21, and the inner side of the end face 24A of the waveguide core 24 of the curved optical waveguide 21. The part 24b includes a second mirror 26B. In this case, the first mirror 26A and the second mirror 26B are formed at positions shifted in the width direction of the waveguide core 24 of the curved optical waveguide 21.

  As described above, the optical waveguide structure 20 is emitted from the first light-emitting element 2 and the first mirror 26 </ b> A that guides the light guided through the outer portion of the waveguide core 24 of the curved optical waveguide 21 to the surface light-receiving element 1. And a second mirror 26B for guiding the light to the inner portion of the waveguide core 24 of the curved optical waveguide 21. That is, in the optical waveguide structure 20, the first mirror 26 </ b> A is provided between the outer portion 24 a of the end face 24 </ b> A of the waveguide core 24 of the curved optical waveguide 21 and the surface light receiving element 1. A second mirror 26 </ b> B is provided between the inner portion 24 b of the end face 24 </ b> A of the waveguide core 24 of the curved optical waveguide 21 and the surface light emitting element 2.

Specifically, for example, as shown in FIG. 7, the optical waveguide structure 20 is formed on a flat substrate (a surface of a flat plate) and includes a clad structure 23 including a plurality of curved grooves 22, and each groove 22. What is necessary is just to provide the waveguide core 24 formed in this, and the clad film 25 which covers the some waveguide core 24. In FIG. 7, the mirror is not shown for convenience of explanation.
Here, the clad structure 23 is a planar structure having a plurality of curved grooves 22 (waveguide grooves; narrow grooves) on the plane of the structure surface.

The waveguide core 24 is formed by filling a curved groove 22 formed in the planar surface layer portion of the cladding structure 23 with a core material (core resin). For this reason, the waveguide core 24 is formed in a curved shape along the surface of the cladding structure 23. That is, the curved optical waveguide 21 has a waveguide core 24 formed on a plane.
The clad film 25 is laminated so as to cover the waveguide core 24 formed in the groove 22 on the plane of the clad structure 23.

By the way, in this embodiment, as shown in FIG. 6, both the optical fiber 10 and the light receiving element 1 and the light emitting element 2 are optically connected by each of the plurality of curved optical waveguides 21 of the optical waveguide structure 20. It is intended to communicate in the direction.
In this case, in addition to the optical waveguide structure 20 including the plurality of curved optical waveguides 21 described above, an optical fiber array 10A including a plurality of optical fibers 10, a light receiving element array 1A including a plurality of light receiving elements 1, and a plurality of light emitting elements. 2A is used.

In this case, as shown in FIG. 6, the optical module 30 includes an optical waveguide structure 20 having a plurality of curved optical waveguides 21 on a plane, a planar light receiving element array 1A, and a planar light emitting element array 2A. It is a multi-channel optical transceiver.
Here, the surface light receiving element array 1A includes a plurality of surface light receiving elements 1 each having a light receiving surface on the surface. Here, the surface light receiving element array 1 </ b> A is a PD array chip including a plurality (four in this case) of photodiodes 1.

The surface light emitting element array 2A includes a plurality of surface light emitting elements 2 having an emission surface on the surface. Here, the surface light emitting element array 2 </ b> A is a VCSEL array chip including a plurality (four in this case) of surface emitting lasers 2.
In this embodiment, each of the plurality of surface light receiving elements 1 included in the surface light receiving element array 1A is optically disposed on each of the outer portions 24a of the end face 24A of the waveguide core 24 of the plurality of curved optical waveguides 21. Connected.

The plurality of surface light emitting elements 2 included in the surface light emitting element array 2A are optically connected to the inner portions 24b of the end faces 24A of the waveguide cores 24 of the plurality of curved optical waveguides 21, respectively. Yes.
Here, the planar light receiving element array 1A and the planar light emitting element array 2A are arranged in parallel along the direction in which the plurality of curved optical waveguides 21 provided in the optical waveguide structure 20 are arranged, and the first mirror 26A and the first mirror 26A Optically connected via two mirrors 26B. Further, the surface light-receiving element array 1A and the surface light-emitting element array 2A are arranged so as to be shifted in the direction in which the waveguide core 24 of the curved optical waveguide 21 extends. Further, the surface light-receiving element 1 and the surface light-emitting element 2 are arranged so as to be shifted in the width direction of the waveguide core 24 of the curved optical waveguide 21 (the groove width direction).

  As described above, in the present embodiment, the surface light receiving element 1 and the surface light emitting element 2 are respectively provided on the one end surface 24A of each curved optical waveguide 21 provided in the optical waveguide structure 20 with the first mirror 26A and the first mirror 26A. Two optically connected via a mirror 26B. The optical fiber 10 is optically connected to the other end face 24B of each curved optical waveguide 21. In this way, the optical fiber 10, the surface light receiving element 1, and the surface light emitting element 2 are optically connected to each other by the plurality of curved optical waveguides 21 formed on the same plane.

  For this reason, the light emitted from each surface light emitting element 2 is guided through the curved optical waveguide 21 and coupled to the optical fiber 10, and the light incident from each optical fiber 10 is also the same curve. The optical waveguide 21 is guided and coupled to the surface light receiving element 1. That is, each curved optical waveguide 21 functions as a reception-side optical waveguide (reception channel) that connects the optical fiber 10 and the surface light-receiving element 1, and at the transmission side that connects the optical fiber 10 and the surface-type light-emitting element 2. It also functions as an optical waveguide (transmission channel).

As described above, in the present embodiment, bidirectional communication is possible by each of the plurality of curved optical waveguides 21 and the plurality of optical fibers 10. In addition, the curved optical waveguide 21 is optically connected to the light receiving element 1 and the light emitting element 2 using the mirrors 26A and 26B, and the height of the entire module can be reduced.
Therefore, according to the optical waveguide structure and the optical module according to the present embodiment, in order to perform bidirectional communication, the number of channels can be increased without increasing the number of optical fibers 10 connected to the optical waveguide structure 20. There is an advantage that can be. It also leads to a reduction in wiring space. In addition, when bidirectional communication is performed, there is an advantage that loss in optically connecting the optical fiber 10 to the light receiving element 1 and the light emitting element 2 can be reduced.

The present invention is not limited to the configuration described in the second embodiment described above, and various modifications can be made without departing from the spirit of the present invention.
For example, in the above-described embodiment, the substrate on which the surface light-receiving element 1 and the surface light-emitting element 2 are mounted is disposed below the optical waveguide structure 20, but the present invention is not limited to this. For example, as shown in FIG. 8, a substrate 27 on which the surface light-receiving element 1 and the surface light-emitting element 2 are mounted may be disposed above the optical waveguide structure 20. In FIG. 8, the same components as those in the above-described embodiment (see FIG. 6) are denoted by the same reference numerals.

Hereinafter, it demonstrates still in detail according to an Example. However, the present invention is not limited to the following examples.
[Example 1]
In the first embodiment, as shown in FIG. 9, an optical waveguide structure (polymer optical waveguide) having a curved optical waveguide 3 on a curved surface and an inclined surface 6x on the end surface 6A of the waveguide core 6 of the curved optical waveguide 3 is provided. 4) Samples 4 were prepared, and transmission / reception performance, that is, loss between the optical fiber 10, the light receiving element 1, and the light emitting element 2 was evaluated. The optical waveguide structure 4 has two surfaces with different angles of an inclined surface 6x and a plane (vertical surface) 6y on the end surface 6A.

In the present Example 1, the optical waveguide structure 4 was produced and used by injection molding (mold molding).
That is, first, a mold 40 was manufactured by stacking thin plates so that the portion where the groove 7 for the waveguide core 6 is formed is convex (see FIG. 10). Then, a clad resin was poured into the mold 40 at a high temperature and cooled, and then the mold 40 was removed to produce a clad structure 8 in which a concave groove 7 for the waveguide core 6 was formed. (See FIG. 10). The resin material to be poured was an olefin resin. The refractive index at a wavelength of 850 nm was 1.5.

Further, when the clad structure 8 was produced by injection molding as described above, the outwardly convex hemispherical lenses 11, 12, 13 were integrally formed on both end faces on the extension line of the groove 7. Here, two hemispherical lenses 11 and 12 are formed on the end face on the side connected to the light receiving element 1 and the light emitting element 2 so as to be aligned in the depth direction of the groove 7.
Here, the groove 7 for the waveguide core 6 is formed to have a width of 50 μm and a depth from 50 μm to 80 μm toward the end face 6A on the side connected to the light receiving element 1 and the light emitting element 2. The inclined surface 6x of 45 degrees was formed on the end face 6A. In this way, the light from the light emitting element 2 and the light from the optical fiber 10 can be separated.

Next, the core liquid is dropped into the groove 7 on the curved surface of the clad structure 8 produced as described above, and the upper part of the groove 7 filled with the core liquid is covered with the clad film 9. The core liquid was sealed and the core liquid was cured to form a waveguide structure.
Here, an ultraviolet curable epoxy resin having a refractive index after curing of 1.56 was used for the core liquid (polymer liquid).

For the clad film 9, an olefin resin film (transparent film; olefin film) having a thickness of 40 μm was used. The refractive index at a wavelength of 850 nm was 1.5.
In this manner, a sample of the optical waveguide structure 4 having the curved optical waveguide 3 on the curved surface and capable of bidirectional communication with a single waveguide was produced.
Next, the sample 4 of Example 1 manufactured as described above was evaluated as follows.

Evaluation of transmission performance, that is, optical coupling loss between the light emitting element and the optical fiber was performed as follows.
A light emitting element (surface emitting laser) 2 having a wavelength of 850 nm is used as a light source, and the sample 4 of Example 1 is aligned and placed on the light emitting surface (light emitting diameter: 10 μm) of the surface emitting laser 2 mounted on the substrate. The light that passed through the sample 4 and emerged on the opposite side was received by a self-aligned GI type multimode optical fiber (core diameter 50 μm) 10 and the output was measured with an optical power meter.

The reception performance, that is, the optical coupling loss between the optical fiber and the light receiving element was evaluated as follows.
Light from an external light source having a wavelength of 850 nm is guided to the end face on the optical fiber side of the sample 4 of the first embodiment through the GI type multimode optical fiber (core diameter 50 μm) 10, and passes through the sample 4 to the opposite side. Was received by a self-aligned GI type multimode optical fiber (core diameter 100 μm), and the output was measured with an optical power meter. Here, in order to measure the optical coupling loss more accurately, it is received by an optical fiber having a core having the same diameter as the light receiving surface (light receiving diameter of 100 μm) of the light receiving element (photodetector) 1 mounted on the substrate. The output is measured with an optical power meter.

Evaluation of how much light emitted from the optical fiber 10 through the sample 4 of Example 1 leaks to the light emitting element 2 side was also performed as follows.
Light from an external light source having a wavelength of 850 nm is guided to the end face on the optical fiber 10 side of the sample 4 of the first embodiment through the GI type multimode optical fiber (core diameter 50 μm) 10, and passes through the sample 4 to be opposite. The light that came out to the side was received by a self-aligned GI type multimode optical fiber (core diameter 100 μm), and the output was measured with an optical power meter.

Here, the distance between the light receiving element 1 and the light emitting element 2 is about 250 μm.
As a result, the optical coupling loss between the light emitting element and the optical fiber in the case where the sample 4 of Example 1 was used was about 4.5 dB. The optical coupling loss between the optical fiber and the light receiving element was about 5.0 dB. Moreover, the leakage loss to the light emitting element 2 side was about 8.5 dB.
As described above, by using the sample 4 of the first embodiment, a large amount of light from the optical fiber 10 is coupled to the light receiving element 1 side, and loss is caused when bidirectional communication is performed by the single waveguide 3. It was confirmed that it could be reduced.
[Example 2]
In the second embodiment, as shown in FIG. 11, an optical waveguide structure (polymer optical waveguide) having a curved optical waveguide 3 on a curved surface, and an end surface 6B of the waveguide core 6 of the curved optical waveguide 3 being flat. 4) Samples 4 were prepared and evaluated for transmission / reception performance, that is, loss between the optical fiber, the light receiving element, and the light emitting element.

Sample 4 of Example 2 was produced in the same manner as in Example 1 except that the end surface 6B was flat (vertical surface) without forming an inclined surface on the end surface.
The evaluation of Sample 4 of Example 2 was also performed in the same manner as in Example 1 described above. However, the distance between the light receiving element 1 and the light emitting element 2 was about 220 μm.
As a result, the optical coupling loss between the light emitting element and the optical fiber in the case where the sample 4 of Example 2 was used was about 4.8 dB. The optical coupling loss between the optical fiber and the light receiving element was about 4.3 dB. The leakage loss to the light emitting element 2 side was about 8.3 dB.

As described above, by using the sample 4 of Example 2, a large amount of light from the optical fiber 10 is coupled to the light receiving element 1 side, and an inclined surface is formed on the end surface of the waveguide core 6 of the curved optical waveguide 3. Even if the end face 6B is made flat (vertical face) without being formed and widened, it has been confirmed that loss can be reduced when bidirectional communication is performed with the single waveguide 3.
Therefore, by using the sample 4 of the first and second embodiments, bidirectional communication with the single optical waveguide 3 becomes possible. In addition, the number of channels per mounting area can be increased. For example, it can be expected that the number of channels will be doubled compared to the case where bidirectional communication is not performed. In addition, the number of wirings can be reduced. For example, if the number of channels is the same, the number of optical fibers to be used can be reduced to half.

DESCRIPTION OF SYMBOLS 1 Surface type light receiving element 1A Surface type light receiving element array 2 Surface type light emitting element 2A Surface type light emitting element array 3 Curved optical waveguide 4, 4A Optical waveguide structure 5, 5A, 5X, 30 Optical module 6 Waveguide core 6A, 6B, 6C, 6D End face 6a, 6d, 6f 1st inclined surface 6b, 6e, 6g 2nd inclined surface 6x inclined surface 6y plane (vertical surface)
7 groove 8 clad structure 9 clad film 10 optical fiber 10A optical fiber array 11 first lens 11A first lens array 12 second lens 12A second lens array 13 third lens 13A third lens array 14 printed circuit board 20 optical waveguide structure Body 21 curved optical waveguide 22 groove 23 clad structure 24 waveguide core 24A end face 24a outer part 24b inner part 25 clad film 26A first mirror 26B second mirror 27 substrate 40 mold

Claims (6)

An optical waveguide structure having a curved optical waveguide that optically connects an optical fiber, a light receiving element, and a light emitting element,
The curved optical waveguide has a waveguide core whose width or thickness increases in a tapered manner toward an end face on the side connected to the light receiving element and the light emitting element,
A light receiving element optically connected to an outer portion of the waveguide core;
An optical module comprising: a light emitting element optically connected to an inner portion of the waveguide core. A curved optical waveguide that optically connects an optical fiber to a light receiving element and a light emitting element,
The curved optical waveguide has a waveguide core whose width or thickness increases in a tapered manner toward an end face on the side connected to the light receiving element and the light emitting element,
A first lens or a first mirror for guiding light emitted from an outer portion of the waveguide core to the light receiving element;
An optical waveguide structure comprising: a second lens or a second mirror that guides light emitted from the light emitting element to an inner portion of the waveguide core. A clad structure having a groove formed on a curved surface;
The waveguide core formed in the groove;
A clad film covering the waveguide core;
The waveguide core has a thickness that is tapered toward the end face on the side connected to the light receiving element and the light emitting element,
A first lens for guiding light emitted from an outer portion of the waveguide core to the light receiving element;
The optical waveguide structure according to claim 2, further comprising a second lens that guides light emitted from the light emitting element to an inner portion of the waveguide core.   4. The optical waveguide structure according to claim 3, wherein the waveguide core includes two surfaces having different angles on the end surfaces connected to the light receiving element and the light emitting element. 5. The curved optical waveguide has the waveguide core formed on a plane,
The waveguide core has a width that is increased in a tapered shape toward an end face on a side connected to the light receiving element and the light emitting element,
A first mirror for guiding light emitted from an outer portion of the waveguide core to the light receiving element;
The optical waveguide structure according to claim 2, further comprising a second mirror that guides light emitted from the light emitting element to an inner portion of the waveguide core.   6. The light guide according to claim 5, wherein an end face position of the waveguide core on a side connected to the light receiving element and the light emitting element is shifted between an outer portion and an inner portion of the waveguide core. Waveguide structure.

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