JP5338652B2 - Optical coupler - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical coupler which achieves stable and high optical coupling efficiency. <P>SOLUTION: The optical coupler 1 optically couples a first optical waveguide 20 and a second optical waveguide 30 and includes a deflection means 11, a supporting means 12 and a grating 13. The deflection means 11 is provided at the opposite side of the substrate 14 of the grating 13 and changes the advancing direction of incident light. The supporting means 12 supports the first optical waveguide 20 connected oppositely to the grating 13 via the deflection means 11. The supporting means 12 is provided at the side of the deflection means 11 and has a height not smaller than that of the deflection means 11. The grating 13 is provided on the substrate 14. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to an optical coupler, and more particularly to an optical coupler including a grating.

  Optical coupling technology using optical waveguides is used in various situations. Among optical coupling technologies, in the input / output optical coupling, if the mode diameter of the input / output light is too large, the input / output light may touch the support substrate that does not contribute to the wave guide, resulting in light loss. .

  On the other hand, in the case of optical coupling using a surface input / output type grating optical coupler (hereinafter referred to as a grating coupler), the input / output light is applied to the support substrate even if the mode diameter of the input / output light is increased. There is no problem that the ratio of touching increases.

  Taking advantage of such a grating coupler, it is considered to butt-connect the grating coupler and the optical fiber (butt joint). As a specific application example, Non-Patent Document 1 discloses that an output of a semiconductor laser emitted from an end face of a chip (substrate) is output to the surface side of the chip via a grating coupler, and an optical fiber connected to the chip A technique for optical coupling is disclosed. Non-Patent Document 2 discloses a technique for optically coupling light from an optical fiber connected to a chip with a thin wire waveguide or a ridge waveguide in the surface direction of the chip (direction parallel to the surface). .

  Normally, under conditions where light is input and output in a direction perpendicular to the substrate, the light incident on the slab waveguide or the grating coupler is diffracted not only on the front surface side of the substrate but also on the back surface side. The optical coupling efficiency is deteriorated. In order to solve this problem, Non-Patent Document 1 also discloses a technique for inputting and outputting light in a slightly oblique direction from the normal direction of the substrate.

  On the other hand, Patent Documents 1 and 2 disclose a technique of installing a prism on a grating coupler. If this technique is used, the incident light can be deflected by a predetermined angle and incident on the grating coupler by entering the light through the prism.

JP-A-6-150425 Japanese Patent Laid-Open No. 9-105669

Niklas Eriksson, Mats Hagberg, and Anders Larsson, "Highly Directional Grating Outcouplers with Tailorable Radiation Characteristics," IEEE Journal of Quantum Electronics, vol. 32, no. 6, pp. 1038-1047, June 1996. Dirk Taillaert, Wim Bogaerts, Peter Bienstman, Thomas F. Krauss, Peter Van Daele, Ingrid Moerman, Steven Verstuyft, Kurt De Mesel, and Roel Baets, "An Out-of-Plane Grating Coupler for Efficient Butt-Coupling Between Compact Planar Waveguides and Single-Mode Fibers, "IEEE Journal of Quantum Electronics, vol. 38, no. 7, pp. 949-955, July 2002.

  However, when matching an optical fiber with a grating coupler, the optical fiber must be as close as possible to the optical coupler in order to obtain high optical coupling efficiency. Then, the optical fiber may come too close to the prism installed on the grating. As a result, there has been a problem that the optical fiber slides on the inclined prism surface to cause a positional shift, or the optical fiber comes into contact with the protrusion on the prism and breaks.

  The present invention has been made to solve such a problem, and an object of the present invention is to provide an optical coupler capable of stably realizing high optical coupling efficiency.

  An optical coupler according to the present invention is an optical coupler that optically couples a first optical waveguide and a second optical waveguide, and is provided on a substrate and connected to the second optical waveguide. And a deflecting unit that is provided on the opposite side of the grating from the substrate and that changes a traveling direction of incident light, and the first optical waveguide connected to the grating via the deflecting unit. Supporting means, and the supporting means is provided on a side of the deflecting means and has a height equal to or higher than the height of the deflecting means.

  The present invention can provide an optical coupler that can stably realize high optical coupling efficiency.

1 is a diagram illustrating a configuration example of an optical coupler according to a first embodiment. 1 is a diagram illustrating a configuration example of an optical coupler according to a first embodiment. FIG. 5 is a diagram illustrating a configuration example of an optical coupler according to a second embodiment. It is a figure which shows the structural example of the optical coupler concerning Embodiment 3. FIG. It is a figure which shows the structural example of the optical coupler concerning Embodiment 4. FIG. 6 is a diagram for explaining a manufacturing process of the optical coupler according to the third and fourth embodiments. FIG. 6 is a diagram for explaining a manufacturing process of the optical coupler according to the third and fourth embodiments. FIG. 6 is a diagram for explaining a manufacturing process of the optical coupler according to the third and fourth embodiments. FIG.

Embodiment 1
Embodiments of the present invention will be described below with reference to the drawings. An optical coupler according to this embodiment is shown in FIG. FIG. 1 is a cross-sectional view of a state in which a first optical waveguide 20 is connected to the optical coupler 1. The optical coupler 1 includes a deflection unit 11, a support unit 12, a grating 13, and a substrate 14. The optical coupler 1 is a device for optically coupling the first optical waveguide 20 (for example, an optical fiber) and the second optical waveguide 30 via the grating 13. The second optical waveguide 30 is connected to the grating 13 and is sandwiched between the upper clad 15 and the lower clad 16.

  The deflecting unit 11 is, for example, a prism made of a polymer, and changes the traveling direction of the light incident on the deflecting unit 11 by refracting or reflecting the passing light. The angle formed by the surface 111 of the deflecting means 11 facing the grating 13 and the surface 112 opposite to the surface is preferably 10 ° to 80 ° in order to increase the diffraction efficiency of the grating 13. . Further, the surface 111 and the surface 112 of the deflecting unit 11 may have a curved surface. By making it a curved surface, it is possible to simultaneously impart a condensing effect (lens effect) to the deflecting means 11.

  The support unit 12 is a support structure disposed on the side of the deflection unit 11, and has a height (length in a direction perpendicular to the substrate 14) that is larger than that of the deflection unit 11. Further, the support unit 12 may be disposed in a part of the periphery of the deflecting unit 11 or may be disposed so as to cover the entire periphery of the deflecting unit 11.

  The grating 13 diffracts incident light from the optical waveguide 20 and light from the second optical waveguide 30 arranged in the surface direction of the substrate 14. In other words, the grating 13 optically couples light incident from the surface direction of the substrate 14 with the first optical waveguide 20, or couples light incident from the first optical waveguide 20 in the surface direction of the substrate 14. Or optical coupling with the second optical waveguide 30. The direction of diffraction is determined by the period of the grating 13 and the polarization direction of the diffracted light. Note that the grating 13 may be one-dimensional, or may be a two-dimensional grating as long as optical coupling for entering or emitting light in two directions is performed.

  Subsequently, optical coupling between the first optical waveguide 20 and the second optical waveguide 30 will be described. The first optical waveguide 20 is connected to the optical coupler 1 so as to face the grating 13 through the deflecting means 11. In other words, the first optical waveguide 20 is butt-connected to the optical coupler 1 in alignment with the deflecting means 11 so that the light 10 emitted from the first optical waveguide 20 enters the deflecting means 11. The At this time, the height of the support means 12 is higher than the height of the deflection means 11. Therefore, the first optical waveguide 20 does not contact the deflection unit 11. As a result, it is possible to avoid displacement and breakage of the first optical waveguide 20.

  Further, as shown in FIG. 1, by causing the support means 12 not to touch the core 200 of the first optical waveguide 20, damage due to the contact between the support means 12 and the core 200 can be avoided. Note that a portion between the first optical waveguide 20 and the deflecting unit 11 is filled with a gas such as vacuum or air, or a medium having a refractive index smaller than that of the deflecting unit.

  When the first optical waveguide 20 is connected to the optical coupler 1, the light 10 emitted from the first optical waveguide 20 is deflected by the deflecting unit 11. Therefore, the light 10 is incident on the grating 13 with a certain angle from the vertical direction with respect to the grating 13.

  The light 10 incident on the grating 13 is diffracted and emitted to the second optical waveguide 30 inside the substrate 14. Thus, the first optical waveguide 20 and the second optical waveguide 30 are optically coupled. The light 10 may be coupled in the direction opposite to the arrow direction in FIG. That is, even if the light 10 is incident on the grating 13 from the second optical waveguide 30 and the light 10 is diffracted by the grating 13 in the surface direction, the first optical waveguide 20 and the second optical waveguide are optically coupled. Good.

  As an operation of the grating 13, the angle at which the light incident from the optical waveguide 20 is diffracted may greatly depend on the wavelength. Similarly, even when light is incident in the reverse direction, the diffraction angle of light in the surface direction of the substrate 14 may change depending on the wavelength of the input light 10. Therefore, if only the grating is used in the configuration of the optical coupler, efficient optical coupling between the first optical waveguide 20 and the first optical waveguide 20 arranged at a fixed angle is limited to a limited wavelength band. It has been done.

  However, according to the configuration of the present invention, the deflection angle of the deflection means 11 can have a wavelength dependency opposite to that of the grating 13, and the angle dependency of the grating 13 can be canceled out. In this way, it is possible to always input and output light in the normal direction of the substrate 14 regardless of the wavelength while maintaining high optical coupling efficiency. As a result, when the first optical waveguide 20 is connected to the optical coupler 1, it is not necessary to incline with a predetermined angle in order to improve the optical coupling efficiency, and the substrate 14 always has a wide wavelength band. Can be connected vertically.

  Such an operation can be used because the grating 13, the deflecting unit 11, and the optical waveguide 20 are arranged very close to each other due to the effect of the indicating unit 12. If not sufficiently close, the input / output light depending on the wavelength of the grating 13 cannot be emitted or incident on the deflecting unit 11 due to the positional deviation. Similarly, the input / output light depending on the wavelength of the deflecting unit 11 cannot be emitted or incident on the first optical waveguide 20 due to the positional deviation.

  Thus, according to the present embodiment, since the height of the support means 12 is higher than the height of the deflecting means 11, the first optical waveguide 20 is connected to the optical coupler 1 when the first optical waveguide 20 is connected. The end face of the waveguide 20 does not come into contact with the deflecting means 11. Therefore, the first optical waveguide 20 can be sufficiently brought close to the deflecting means 11 and the grating 13, and mutual displacement can be avoided. That is, stable optical coupling efficiency can be realized. Further, damage due to contact between the first optical waveguide 20 and the deflecting means 11 can be prevented.

  Another problem is solved by this embodiment. That is, when the first optical waveguide 20 to be optically coupled as in the prior art is fixed at a certain distance from the deflecting means 11, a measuring instrument for measuring the certain distance or the first optical waveguide 20 is suspended. And a device for fixing is required. As a result, the manufacturing cost of the optical coupler increases, and the structure of the entire optical coupler becomes large and complicated.

  On the other hand, according to the configuration of the optical coupler 1 according to the present invention, it is possible to connect the first optical waveguide 20 on the support unit 12 with a certain distance from the deflecting unit 11 by contacting the first optical waveguide 20. As a result, a measuring instrument for measuring a certain distance and a device for suspending the first optical waveguide 20 are not required, and the manufacturing cost of the optical coupler 1 can be reduced. In addition, the size and complexity of the optical coupler can be suppressed.

  Since a small-sized optical coupler can be realized, it can be disposed close to other input / output structures such as an input / output unit for electric signals. For example, as shown in FIG. 2, the optical coupler 1 shown in FIG. 1 may be further arranged in the vicinity of the bonding wire 17. By doing so, the input and output parts of light and electricity can be arranged with high density.

Embodiment 2
A second embodiment according to the present invention will be described. The optical coupler 2 shown in FIG. 3 further includes guiding means 21 in addition to the configuration of the optical coupler 1. Since other configurations are the same as those of the optical coupler 1, description thereof is omitted.

  The guide means 21 is erected on the support means 12 with a distance substantially equal to the width of the diameter of the first optical waveguide 20. As shown in FIG. 3, the guiding unit 21 is disposed so as to surround the deflecting unit 11, and therefore, the first optical waveguide 20 is inserted into the guiding unit 21 to insert the first optical waveguide at an appropriate position. The waveguide 20 is guided and connected to the optical coupler 2.

  As described above, according to the present embodiment, the positional relationship between the first optical waveguide 20 and the deflecting unit 11 can be easily adjusted with high accuracy simply by inserting the first optical waveguide 20 in accordance with the guiding unit 21. be able to. Therefore, it is possible to reduce the cost and labor for position adjustment in the manufacturing process. In addition, as shown in FIG. 3, the insertion of the 1st optical waveguide 20 becomes easy by widening the part of an insertion port.

  Moreover, it is preferable to manufacture the deflection | deviation means 11, the support means 12, and the guidance means 21 integrally. Since the positional relationship between the deflecting means 11 and the guiding means 21 is fixed at the manufacturing stage, the positional accuracy can be further improved.

Embodiment 3
A third embodiment according to the present invention will be described. The configuration of the optical coupler 3 shown in FIG. 4 is a configuration when applied to an array fiber. That is, this is a configuration in which a plurality of first optical waveguides 20 are bundled and connected to the optical coupler 3. The optical coupler 3 has a configuration in which a plurality of optical couplers 1 are connected. Since other configurations are the same as those of the optical coupler 1, description thereof is omitted.

  The connection between the first optical waveguide 20 and the optical coupler 3 is the same as described in the first embodiment. In FIG. 4, the two first optical waveguides 20 (201, 202) located on the left side enter the light 10 into the optical coupler 3. On the other hand, the light 10 emitted from the optical coupler 3 is incident on the two first optical waveguides 20 (203, 204) located on the right side.

  As described above, the present invention can also be applied to the case where the optical coupler 3 according to the present embodiment is optically coupled to the fiber array. Further, as described above, the grating 13 and the second optical waveguide 30 are adjusted by adjusting the angle of the deflecting means 11 so that the incident / exit light 10 of the optical coupler 3 is substantially perpendicular to the substrate 14. The light 10 can be input / output in a direction substantially perpendicular to the substrate 14 regardless of the direction of the light. Therefore, the first optical waveguide 20 can also be connected to the substrate 14 in a substantially vertical direction. As a result, since it is not necessary to consider the direction in which the fiber array is inclined, the first optical waveguide 20 can be closely connected, and the degree of freedom in designing the optical circuit is not limited.

Embodiment 4
A fourth embodiment according to the present invention will be described. The structure of the optical coupler 4 shown in FIG. 5 is a structure in the case of attaching to an interposer. The interposer 40 includes a first optical waveguide 20 and a lens 41. The first optical waveguide 20 (205 to 208) is provided in the interposer 40. The configuration of the optical coupler 4 is the same as the configuration of the optical coupler 3 shown in FIG. The solder ball 50 is used for flip chip bonding.

  The connection between the interposer 40 and the optical coupler 4 will be described. A mirror 210 is provided at the end of each first optical waveguide 20, and the light 10 that has propagated through the first optical waveguides 205 and 206 is reflected by the mirror 210 perpendicularly to the substrate 14, so that the light The light enters the coupler 4. Further, the light 10 emitted from the optical coupler 4 is reflected in parallel to the substrate 14 by the mirror 210 and is incident on the first optical waveguides 207 and 208.

  At this time, as shown in FIG. 5, the interposer 40 and the optical coupler 4 are brought close to each other. In the present invention, the support means 12 and the interposer 40 and the lens 41 are in contact with each other, but there is a certain distance between the deflection means 11 and the interposer 40 and the lens 41. Therefore, the light input / output surfaces of the deflecting unit 11 and the interposer 40 and the lens 41 facing the deflecting unit 11 are not damaged.

  Here, the first optical waveguides 206 and 208 positioned below the interposer 40 have a larger distance from the optical coupler 4 than the first optical waveguides 205 and 207. Therefore, the light 10 reflected by the mirror 210 of the first optical waveguide 206 propagates a long distance and enters the optical coupler 4. As a result, the beam diameter of the light 10 after being reflected by the mirror 210 becomes too large and the light deviating from the incident surface of the deflecting means 11 is lost. In order to prevent such loss, a lens 41 is provided.

  As described above, the configuration of the optical coupler 4 according to the present embodiment is used as an optical coupler even in the case of optical coupling with the first optical waveguide 20 provided in the interposer 40. be able to. Of course, since the support means 12 is provided, stable optical coupling efficiency can be realized, damage can be prevented, and costs can be reduced.

  Here, an example of a manufacturing method of the optical couplers 3 and 4 shown in FIGS. 4 and 5 will be briefly described. 6-8 is a figure which shows the manufacturing process of the optical coupler concerning this invention. First, a polymer is applied on the grating (see FIG. 6). Next, embossing is performed by nanoimprint or the like (see FIG. 7). Then, the polymer remaining in the portion other than the optical coupler is removed by using etch back (see FIG. 8). Through the steps as described above, the optical coupler according to the present invention can be easily manufactured.

  Note that the present invention is not limited to the above-described embodiment, and can be changed as appropriate without departing from the spirit of the present invention.

1-4 optical coupler 10 light 11 deflecting means 12 support means 13 grating 14 substrate 15 upper clad 16 lower clad 17 bonding wire 20 201-208 first optical waveguide 21 guiding means 30 second optical waveguide 40 interposer 41 Lens 50 Solder ball 200 Core 210 Mirror

Claims (6)

An optical coupler that optically couples a first optical waveguide and a second optical waveguide,
A grating provided on the substrate and connected to the second optical waveguide;
A deflecting means that is provided on the opposite side of the grating from the substrate and changes the direction in which the incident light travels;
Support means for supporting the first optical waveguide connected to the grating via the deflection means;
With
Said support means is provided on the side of the deflecting means, have a height above the height of said deflecting means,
The deflecting unit is an optical coupler that causes diffracted light from the grating to enter and exit in a direction substantially perpendicular to the substrate . 2. The optical coupler according to claim 1, further comprising a guiding unit that stands on the supporting unit, into which the first optical waveguide is inserted, and that guides the first optical waveguide to the deflecting unit. 3. The light according to claim 1, wherein an angle formed between a surface of the deflecting unit facing the grating and a surface positioned on the opposite side of the surface facing the grating is an angle of 10 ° to 80 °. Combiner. The grating optical coupler according to any one of claims 1 to 3 having a periodicity of one-dimensional or two-dimensional. It said support means includes an optical coupler according to any one of claims 1 to 4, wherein the deflection means and materials are the same. It said deflecting means is an optical coupler according to any one of claims 1 to 5 which is a polymer.

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