WO2006103850A1

WO2006103850A1 - Waveguide element and laser generator

Info

Publication number: WO2006103850A1
Application number: PCT/JP2006/303240
Authority: WO
Inventors: Shigeo Kittaka; Tatsuhiro Nakazawa
Original assignee: Nippon Sheet Glass Company, Limited
Priority date: 2005-03-25
Filing date: 2006-02-23
Publication date: 2006-10-05
Also published as: JPWO2006103850A1

Abstract

A waveguide element (1) comprising a resonance photonic crystal waveguide (3) composed of a photonic crystal having a refractive index periodicity in one direction and having a core for propagating in a non-refractive-index-periodicity direction an electromagnetic wave existing on Brillouin zone boundary, and resonance mechanisms (4, 5). The resonance photonic crystal waveguide (3) satisfies the condition, a/λ0<1/(2nS), when the refractive index of a homogenous medium in contact with side surface of the core in parallel to the refractive-index-periodicity direction of the core is nS, the refractive index periodicity of the core a, and the wavelength in vacuum of an electromagnetic wave propagating through the core λ0. Accordingly, the waveguide element is easy to produce due to its simple structure and high in design freedom, and can be integrated.

Description

Specification

Waveguide element and laser generator

Technical field

The present invention relates to a waveguide element and a laser generator using a one-dimensional photonic crystal.

Background art

[0002] Various optical elements having a structure in which a waveguide is disposed on a substrate, that is, waveguide elements, have already been put into practical use. In particular, recently, a defect waveguide using a two-dimensional photonic crystal (a two-dimensional photonic crystal defect waveguide) has attracted attention, and its research and development has been actively conducted.

. Hereinafter, the structure of the defect waveguide will be described. First, a two-dimensional photonic crystal having a refractive index periodic structure is constructed by arranging regular vacancies in a thin film layer using, for example, Si having a high refractive index. This two-dimensional photonic crystal is configured to form a complete photonic band gap in the operating frequency range in a direction having refractive index periodicity (hereinafter referred to as “refractive index periodic direction” t). Is done. Furthermore, a defect waveguide is formed by providing a linear defect (line defect) in the two-dimensional photonic crystal. Light can propagate through the defect portion of the defect waveguide, and cannot propagate through the area where no defect is provided. This defect waveguide has a feature that it can be bent at a steep angle (steep angle). Therefore, by using this defect waveguide as a wiring, the degree of freedom in designing the optical circuit is increased, and the optical circuit can be miniaturized or integrated. By using this defect waveguide as a part of the optical element, the optical element can be miniaturized.

[0003] Furthermore, it is possible to cause a group velocity abnormality in the light propagating in the defect waveguide. Therefore, when this defect waveguide is used as a part of the optical element, the nonlinear effect can be increased to improve the characteristics of the optical element or to reduce the size.

[0004] Further, the defect waveguide has a feature that it can completely confine light.

[0005] Based on the above, various optics that take advantage of the properties of two-dimensional photonic crystal defect waveguides Devices have been proposed (see, for example, Patent Documents 1 to 5 and Non-Patent Documents 1 to 10). These are described below.

[0006] First, Patent Documents 1 and 2 describe an optical element including a defect waveguide configured by providing a line defect in a two-dimensional photonic crystal and a resonator configured by providing a point defect. It is disclosed. Furthermore, Non-Patent Document 1 discloses an optical element that achieves high efficiency by providing multistage resonators due to point defects.

[0007] Further, Patent Document 3 discloses an optical element including a resonator configured by providing a line defect in a ring shape in a two-dimensional photonic crystal.

[0008] Further, Non-Patent Document 2 discloses an optical element in which two wavelengths are separated by a multimode force bra in which the width of a two-dimensional photonic crystal defect waveguide is partially increased. Patent Document 4 discloses an all-optical flip-flop element using a multimode force bra.

[0009] Patent Document 5, Non-Patent Documents 3 and 4 disclose light-emitting elements in which quantum dots are incorporated in defects of a photonic crystal.

[0010] Further, Patent Document 6, Non-Patent Documents 5, 6, 7, 8, 9 and 10 disclose an optical switch using a non-linear action using a two-dimensional photonic crystal defect waveguide.

As described above, the two-dimensional photonic crystal defect waveguide is used in various optical elements.

Patent Document 1: Japanese Patent Application Laid-Open No. 2004-119671

Patent Document 2: JP 2004-212416 A

Patent Document 3: Japanese Patent Laid-Open No. 2004-170478

Patent Document 4: Japanese Patent No. 3578737

Patent Document 5: Japanese Patent Application Laid-Open No. 2004-296560

Patent Document 6: Japanese Unexamined Patent Application Publication No. 2004-93787

Non-Patent Document 1: 3p— ZC— 6, Proceedings of the 65th JSAP Autumn Meeting 2004, September 1, 2004, p. 934

Non-Patent Document 2: OPTICS EXPRESS (USA) October 31, 2004 No.12 卷 23 p. 5625 Non-Patent Document 3: 3a—ZC—10, Proceedings of the 65th JSAP Autumn Meeting 2004, September 1, 2004, p. 931

Non-Patent Document 4: 3a- ZC-11, Proceedings of the 65th JSAP Autumn Meeting 2004, September 1, 2004, p. 931

Non-Patent Document 5: 4a— ZC— 10, Proceedings of the 65th JSAP Autumn Meeting 2004, September 1, 2004, p. 941

Non-Patent Document 6: 4p— ZC— 2, Proceedings of the 65th JSAP Autumn Meeting 2004, September 1, 2004, p. 942

Non-Patent Document 7: 4p— ZC— 3, Proceedings of the 65th JSAP Autumn Meeting 2004, September 1, 2004, p. 942

Non-Patent Document 8: 4p— ZC— 5, Proceedings of the 65th JSAP Autumn Meeting 2004, September 1, 2004, p. 943

Non-Patent Document 9: 4p— ZC— 6, Proceedings of the 65th JSAP Autumn Meeting 2004, September 1, 2004, p. 943

Non-Patent Document 10: 4p— ZC— 7, Proceedings of the 65th JSAP Autumn Meeting 2004, September 1, 2004, p. 944

Disclosure of the invention

Problems to be solved by the invention

However, the two-dimensional photonic crystal defect waveguide has the following problems.

[0013] First, the first problem will be described. In the refractive index periodic direction (plane direction), the light is completely confined by the photonic band gap. In the direction where the refractive index is constant (vertical direction), the light confinement is incomplete and propagation. The loss is large. In this waveguide, in order to prevent light leakage in the vertical direction, a so-called “air bridge structure” has been devised in which the upper and lower claddings are air layers. The structure is complicated and has high manufacturing costs.

[0014] Next, the second problem will be described. In order to complete the photonic band gap in the planar direction (refractive index periodic direction), the materials forming the refractive index periodic structure It is necessary to increase the refractive index difference. Therefore, in general, a photonic crystal made of a high refractive index material (for example, Si having a refractive index of 3.48) and air is produced. However, in this case, the refractive index of the defect portion forming the core of the waveguide becomes very large, so that the cross section of the core becomes very small to satisfy the single mode condition (typically 1 m x 1 m or less). And the difference between the cross section of the core of the waveguide and the cross section of the single mode fiber (about the diameter of the core) coupled to the waveguide becomes large, making it difficult to efficiently couple them. Also, at the interface where the refractive index difference is large, leaking light is more likely to occur due to a weak defect, and the propagation loss of the waveguide increases.

Next, the third problem will be described. In the two-dimensional photonic crystal, there is a problem that the arrangement becomes a restriction in designing the waveguide element. Here, for example, a description will be given of design constraints when a two-dimensional photonic crystal is formed by arranging triangular holes in a uniform medium. First, there are two types of light bending angles: 60 ° and 120 °. The width of the waveguide is N times the period (N is a natural number), such as “without one row” or “without two rows”. In addition, the size and shape of point defects is N holes, and the distance between point defects in the waveguide is N times the period. Such a configuration is a natural and preferable force in a two-dimensional photonic crystal. Therefore, design parameters, such as the resonance frequency of the resonator, take discrete values and select a desired value. I couldn't. In order to solve this problem, for example, an in-plane heterostructure two-dimensional photonic crystal as disclosed in Non-Patent Document 1 may be used. However, the design cost and the manufacturing cost increase. There was a point.

[0016] The present invention has been made to solve the above-described problems in the prior art, and can be easily manufactured because of its simple configuration, and can be integrated with a high degree of design freedom. An object of the present invention is to provide a waveguide element and a laser generator.

Means for solving the problem

In order to achieve the above object, a first configuration of the waveguide element according to the present invention is configured by a photonic crystal having a refractive index periodicity in one direction, and does not have the refractive index periodicity. A waveguide device comprising a resonant photonic crystal waveguide having a core for propagating electromagnetic waves existing on the Brillouin zone boundary, wherein the resonant photonic crystal waveguide The path propagates through the core with n as the refractive index of the homogeneous medium in contact with the side of the core parallel to the direction having the refractive index periodicity of the core, a as the refractive index period of the core.

S

When the wavelength of electromagnetic waves in vacuum is estimated,

0

a / λ <l / (2n)

0 S

It satisfies the following conditions.

[0018] A second configuration of the waveguide element according to the present invention is a waveguide element including a slab-like photonic crystal waveguide, an incident-side photonic crystal waveguide, and a plurality of output-side photonic crystal waveguides. The slab-like photonic crystal waveguide extends in a direction parallel to a plane perpendicular to a direction having a refractive index periodicity, and the incident-side photonic crystal waveguide is the slab-like photonic crystal The plurality of output-side photonic crystal waveguides are connected to a surface of the slab-like photonic crystal waveguide that faces the surface to which the incident-side photonic crystal waveguide is connected. The slab photonic crystal waveguide, the incident side photonic crystal waveguide, and the plurality of output side photonic crystal waveguides each have a refractive index periodicity in one direction. The photonic crystal has a core that propagates electromagnetic waves that exist on the Brillouin zone boundary in the direction without the refractive index periodicity, and is parallel to the direction having the refractive index periodicity. The refractive index of the homogeneous medium in contact with the side of the core is n, the refractive index period of the core is a,

S

If the wavelength of the electromagnetic wave propagating in the vacuum is 0,

a / λ <l / (2n)

0 S

It satisfies the following conditions.

In addition, the configuration of the laser generator according to the present invention is configured by a photonic crystal having a refractive index periodicity in one direction, and an electromagnetic wave existing on the Brillouin zone boundary in a direction not having the refractive index periodicity. A laser generator comprising an excitation photonic crystal waveguide having a core for propagating light, and an excitation mechanism for exciting the excitation photonic crystal waveguide to oscillate laser light, the excitation photonic crystal waveguide The refractive index of the homogeneous medium in contact with the side surface of the core parallel to the direction of the refractive index periodicity of the core is n, the refractive index period of the core is a, and the electromagnetic wave propagating in the core In vacuum

S

When the wavelength is estimated, a / λ <l / (2n)

0 s

The above core is satisfied, and the core has a light emitting action.

The invention's effect

[0020] According to the present invention, it is possible to provide a waveguide element and a laser generator that can be easily manufactured because of a simple configuration and that can be integrated with a high degree of design freedom. . Brief Description of Drawings

FIG. 1 is a cross-sectional view showing a configuration of a one-dimensional photonic crystal in an embodiment of the present invention.

FIG. 2 is a band diagram of the photonic crystal shown in FIG.

FIG. 3 is a band diagram when incident light is obliquely incident on the incident side end face of the one-dimensional photonic crystal in the embodiment of the present invention.

FIG. 4 is a band diagram of the one-dimensional photonic crystal when the propagation directions of the propagation light of the first band and the second band are both in the Z-axis direction in the embodiment of the present invention.

FIG. 5 is a band diagram showing the band diagram on the Brillouin zone boundary in FIG. 4 limited to the Z-axis direction.

[Fig. 6] Fig. 6 is a schematic diagram showing an electric field when traveling in the one-dimensional photonic crystal in an embodiment of the present invention while being inclined with respect to the direction of the propagating light force and the third axis.

FIG. 7A is a cross-sectional view showing a configuration of a photonic crystal waveguide having a cladding and a core of a one-dimensional photonic crystal in an embodiment of the present invention.

FIG. 7B is a perspective view showing a configuration of a photonic crystal waveguide having a cladding and a core of a one-dimensional photonic crystal in an embodiment of the present invention.

FIG. 8 is a perspective view showing a configuration of a waveguide element in accordance with the first exemplary embodiment of the present invention.

FIG. 9 is a plan view showing the configuration of the waveguide element according to the first embodiment of the present invention.

FIG. 10 is a perspective view showing a configuration of a waveguide element in accordance with the second exemplary embodiment of the present invention.

FIG. 11 is a plan view showing the configuration of the waveguide element according to the third embodiment of the present invention. is there.

FIG. 12 is a plan view showing a configuration of a waveguide element in the fourth exemplary embodiment of the present invention.

FIG. 13 is a perspective view showing a configuration of a waveguide element in accordance with the fifth exemplary embodiment of the present invention.

FIG. 14 is a perspective view showing a configuration of a waveguide element according to the sixth embodiment of the present invention.

FIG. 15 is a perspective view showing a configuration of a waveguide element according to the seventh embodiment of the present invention.

FIG. 16A is a plan view showing a configuration of a waveguide element and an optical path in Embodiment 8 of the present invention, and shows a state in which signal light is emitted in the middle as an output waveguide force. .

FIG. 16B is a plan view showing the configuration of the waveguide element and the optical path in the eighth embodiment of the present invention, and shows a state in which the signal light is emitted from the end of the output waveguide force.

FIG. 17 is a perspective view showing a configuration of a laser generator according to the tenth embodiment of the present invention.

FIG. 18 is a perspective view showing a configuration of a laser generator in an eleventh embodiment of the present invention.

FIG. 19 is a perspective view showing a configuration of a laser generator according to the twelfth embodiment of the present invention.

FIG. 20 is a perspective view showing a configuration of a laser generator in the thirteenth embodiment of the present invention.

FIG. 21 is a perspective view showing a configuration of a waveguide element according to the fourteenth embodiment of the present invention.

FIG. 22 is a perspective view showing a configuration of a waveguide element having two resonance portions according to the fourteenth embodiment of the present invention.

FIG. 23 shows the structure of a waveguide element that is a branching element in Embodiment 14 of the present invention. It is a perspective view which shows composition.

FIG. 24 is a perspective view showing a configuration of a waveguide element according to the fifteenth embodiment of the present invention.

FIG. 25 is a perspective view showing a configuration of a waveguide element according to the sixteenth embodiment of the present invention.

FIG. 26 is a perspective view showing the configuration of the waveguide element according to the seventeenth embodiment of the present invention.

BEST MODE FOR CARRYING OUT THE INVENTION

[0022] A first configuration of the waveguide element of the present invention includes a resonant photonic crystal waveguide configured to resonate, which is configured by a one-dimensional photonic crystal waveguide. For this reason, the resonant photonic crystal waveguide can resonate evanescent waves of all directional forces perpendicular to the direction having the refractive index periodicity of the core. The resonant photonic crystal waveguide is

It is possible to freely design the size, shape, electromagnetic wave bending angle, etc., which has a high degree of design freedom. As a result, it is possible to realize a waveguide element that can be integrated and has a higher function. In addition, the one-dimensional photonic crystal waveguide is a multilayer structure and can be easily manufactured.

[0023] The first configuration of the waveguide element of the present invention preferably further includes a resonance mechanism that causes resonance in the resonant photonic crystal waveguide.

In this case, the resonance mechanism is substantially perpendicular to the optical axis of the resonant photonic crystal waveguide, and the refractive index of the core of the resonant photonic crystal waveguide is periodic. An evanescent wave is coupled to the core of the resonant photonic crystal waveguide from a direction substantially perpendicular to the direction having the optical axis, and the optical axis of the resonant photonic crystal waveguide is within the resonant photonic crystal waveguide. It is preferable that resonance is generated in a direction substantially perpendicular to the core and substantially perpendicular to the direction having the refractive index periodicity of the core of the resonant photonic crystal waveguide. According to this preferred example, a waveguide for propagating electromagnetic waves that cause resonance can be disposed on the substrate. For this reason, since the waveguide may be a photonic crystal waveguide, the fabrication of the waveguide element is facilitated. [0025] In this case, the resonance mechanism further includes the refractive index periodicity of the core of the resonant photonic crystal waveguide and substantially perpendicular to the optical axis of the resonant photonic crystal waveguide. Two waveguides having an optical axis substantially perpendicular to the direction in which they are disposed, spaced apart from the resonant photonic crystal waveguide and sandwiching the resonant photonic crystal waveguide, Each of the two waveguides is composed of a photonic crystal having a refractive index periodicity in one direction, and a photonic crystal having a core for propagating an electromagnetic wave existing on the Brillouin zone boundary in a direction not having the refractive index periodicity. The photonic crystal waveguide is parallel to a direction having the refractive index periodicity of the core of the photonic crystal waveguide. N is the refractive index of the homogeneous medium in contact with the side surface of the photonic crystal waveguide, and the refractive index period of the core of the photonic crystal waveguide is

S1

A in a vacuum of electromagnetic waves propagating in the core of the photonic crystal waveguide

1

If the wavelength is 01,

a / λ <1 / (2η)

1 01 SI

It is preferable to satisfy the following condition. According to this preferred example, it is possible to realize a waveguide element capable of causing resonance in the resonant photonic crystal waveguide.

[0026] In this case, the resonance mechanism preferably couples an evanescent wave to the core of the resonant photonic crystal waveguide in the same directional force as the optical axis of the resonant photonic crystal waveguide. . According to this preferred example, the signal light propagating in the resonant photonic crystal waveguide and the control light resonating in the resonant photonic crystal waveguide can be propagated using the same waveguide. This will reduce the size of the waveguide element.

[0027] In this case, the resonance mechanism further has the same optical axis as the optical axis of the resonant photonic crystal waveguide, and is separated from the resonant photonic crystal waveguide so as to be separated from the resonant photonic crystal waveguide. The two waveguides are arranged by sandwiching a crystal waveguide, and each of the two waveguides is composed of a photonic crystal having a refractive index periodicity in one direction, and the refractive index periodicity is A photonic crystal waveguide having a core that propagates electromagnetic waves existing on the Brillouin zone boundary in the ヽ direction, wherein the photonic crystal waveguide is the refractive index period of the core of the photonic crystal waveguide Parallel to the direction The refractive index n of the homogeneous medium in contact with the side surface of the core of the tonic crystal waveguide is n

S1 The refractive index period of the core of the photonic crystal waveguide is a, the photonic crystal waveguide

1

When the wavelength of the electromagnetic wave propagating in the core is in vacuum,

01

a / λ <1 / (2η)

1 01 SI

In this case, the resonant photonic crystal waveguide sandwiches the core from the direction having the refractive index periodicity of the core, and is the same as the direction of the core having the refractive index periodicity. A clad having a refractive index periodicity in the direction of the resonance photonic crystal waveguide from the direction of the refractive index periodicity of the core of the resonant photonic crystal waveguide. It is preferable to couple a light wave to the core to cause resonance in the resonant photonic crystal waveguide in a direction having the refractive index periodicity of the core of the resonant photonic crystal waveguide. According to this preferred example, it is possible to realize a waveguide element capable of causing resonance in the resonant photonic crystal waveguide.

[0029] In this case, the resonance mechanism further includes an optical axis along a direction having the refractive index periodicity of the core of the resonance photonic crystal waveguide, and the resonance photonic crystal guide It is preferable to have a light incident portion that is spaced apart from the waveguide. According to this preferred example, it is possible to realize a waveguide element capable of causing resonance in a resonant photonic crystal waveguide.

Furthermore, in this case, it is preferable that the light incident portion includes an optical waveguide and a lens that collects light from the optical waveguide. According to this preferred example, it is possible to realize a waveguide element capable of causing resonance in the resonant photonic crystal waveguide.

[0031] Further, in this case, the light incident portions are arranged in a line along a plane perpendicular to the direction of the refractive index periodicity of the core of the resonant photonic crystal waveguide. Preferably, each of the plurality of light sources emits light independently. According to this preferred example, the output of the control light that causes resonance can be increased. The In addition, since multiple light sources can selectively emit control light, the path of propagating light can be controlled even if the number of waveguides is increased or the shape of the waveguides is complicated. I'll do it.

[0032] Furthermore, the resonant photonic crystal waveguide has a slab-like portion that extends along a plane perpendicular to the direction of the refractive index periodicity of the core of the resonant photonic crystal waveguide. It is preferable. According to this preferred example, by selectively emitting control light from a plurality of light sources, the path of propagation light in the slab-like portion can be controlled to be in a desired direction.

[0033] In this case, it is preferable that the core of the resonant photonic crystal waveguide has a non-linear action. According to this preferable example, it is possible to improve the characteristics as a light control element by causing a large non-linear effect.

In this case, it is preferable that the core of the resonant photonic crystal waveguide has an amplifying function. According to this preferable example, a waveguide element which is an amplifying element can be realized.

[0035] In the first configuration of the waveguide element of the present invention, the resonant photonic crystal waveguide is preferably ring-shaped. As described above, this preferable example includes a ring-shaped resonant photonic crystal waveguide that is configured by a one-dimensional photonic crystal waveguide and that performs resonance. As a result, the resonant length of the resonant photonic crystal waveguide can be lengthened, so that a plurality of frequencies at regular intervals can be resonated. In addition, by using a time delay required for propagation, an optical buffer memory or a waveguide element that is a multiple pulse generating element can be realized.

[0036] Further, in the first configuration of the waveguide element of the present invention, an incident-side photonic crystal waveguide and an exit-side photonic crystal waveguide are further provided, and the incident-side photonic crystal waveguide is disposed inside the waveguide element. Among a plurality of propagating electromagnetic waves having different wavelengths, an electromagnetic wave having a resonance frequency of the resonant photonic crystal waveguide is resonated in the resonant photonic crystal waveguide and is emitted to the output side photonic crystal waveguide. The incident-side photonic crystal waveguide, the resonant photonic crystal waveguide, and the output-side photonic crystal waveguide are disposed so as to propagate, and the incident-side photonic crystal waveguide and the output-side photonic crystal waveguide are disposed. Nick Each of the crystal waveguides is composed of a photonic crystal having a refractive index periodicity in one direction, and a core that propagates an electromagnetic wave that exists on the Brillouin zone boundary in the direction without the refractive index periodicity. A side surface of the core of the photonic crystal waveguide parallel to a direction having the refractive index periodicity of the core of the photonic crystal waveguide. The refractive index of the homogeneous medium in contact with n is n and the refractive index period of the core of the photonic crystal waveguide is a.

S1 1 The wavelength of the electromagnetic wave propagating in the core of the nick crystal waveguide in vacuum.

01

a / λ <l / (2n)

1 01 SI

It is preferable to satisfy the following condition. According to this preferred example, a waveguide element that is a resonant element can be realized.

The first configuration of the waveguide element of the present invention further includes an incident-side photonic crystal waveguide and an output-side photonic crystal waveguide, and includes a plurality of the resonant photonic crystal waveguides. Among the plurality of electromagnetic waves having different wavelengths propagating in the side photonic crystal waveguide, the electromagnetic waves having the resonance frequency of the resonant photonic crystal waveguide sequentially resonate in the plurality of resonant photonic crystal waveguides. The incident-side photonic crystal waveguide, the plurality of resonant photonic crystal waveguides, and the output-side photonic crystal waveguide are disposed so as to propagate to the output-side photonic crystal waveguide, The entrance-side photonic crystal waveguide and the exit-side photonic crystal waveguide are each made of a photonic crystal having a refractive index periodicity in one direction. The photonic crystal waveguide has a core that propagates electromagnetic waves that exist on the Brillouin zone boundary in the negative direction without the refractive index periodicity, and the photonic crystal waveguide is a photonic crystal waveguide described above. The refractive index of the homogeneous medium in contact with the side surface of the core of the photonic crystal waveguide parallel to the direction having the refractive index periodicity of the core of the nic crystal waveguide is n,

SI

The refractive index period of the core of the photonic crystal waveguide is a, and the photonic crystal guide

1

When the wavelength in the vacuum of the electromagnetic wave propagating in the core of the waveguide is estimated,

01

a / λ <1 / (2η)

1 01 SI

It is preferable to satisfy the following condition. According to this preferred example, it has a flat top characteristic. A waveguide element can be realized.

In the first configuration of the waveguide element of the present invention, the waveguide device further includes an incident-side photonic crystal waveguide and a plurality of emission-side photonic crystal waveguides, and the plurality of emission-side photonic crystal waveguides are provided. There are as many resonant photonic crystal waveguides as there are waveguides, the resonant frequencies of the plurality of resonant photonic crystal waveguides are different from each other, and the wavelengths propagating through the incident-side photonic crystal waveguide are different. Among a plurality of electromagnetic waves, each electromagnetic wave having a resonance frequency for each of the resonant photonic crystal waveguides resonates in the corresponding resonant photonic crystal waveguide, and enters the corresponding output-side photonic crystal waveguide. The incident-side photonic crystal waveguide, the plurality of resonant photonic crystal waveguides, and the plurality of exit-side photonic connections so as to propagate. The incident-side photonic crystal waveguide and the plurality of exit-side photonic crystal waveguides are each composed of a photonic crystal having a refractive index periodicity in one direction, and the bending is performed. A photonic crystal waveguide having a core for propagating electromagnetic waves existing on a Brillouin zone boundary in the ヽ direction without rate periodicity, wherein the photonic crystal waveguide is the core of the photonic crystal waveguide The refractive index of the homogeneous medium in contact with the side of the core of the photonic crystal waveguide parallel to the direction having the refractive index periodicity of n

The refractive index period of the core of the photonic crystal waveguide S1 is a, and the photonic crystal waveguide

1

When the wavelength of the electromagnetic wave propagating in the core of the path is set to 01, a / λ <1 / (2η)

1 01 SI

It is preferable to satisfy the following condition. According to this preferable example, a waveguide element which is a wavelength separation element can be realized.

The second configuration of the waveguide element of the present invention includes a one-dimensional photonic crystal waveguide and functions as a multimode force bra. The design of a waveguide using a one-dimensional photonic crystal waveguide can freely design the size and shape of the waveguide, the bending angle of the electromagnetic wave, etc. with a high degree of freedom. As a result, it is possible to realize integration and a higher-performance waveguide element. In addition, since the one-dimensional photonic crystal waveguide is a multilayer structure, it can be easily manufactured.

[0040] Further, in the second configuration of the waveguide element of the present invention, the slab-like photomask is used. The crystal waveguide preferably splits the light incident from the incident-side photonic crystal waveguide and causes the light to enter each of the plurality of output-side photonic crystal waveguides. According to this preferred example, a waveguide element that is a branch element can be realized.

[0041] In the second configuration of the waveguide element of the present invention, the slab-shaped photonic crystal waveguide has a plurality of different wavelengths incident from the incident-side photonic crystal waveguide. It is preferable that the light is separated for each wavelength and is incident on each of the plurality of emission-side photonic crystal waveguides. According to this preferred example, a waveguide element that is a wavelength separation element can be realized.

In addition, the configuration of the laser generator of the present invention can excite laser light by resonance in the one-dimensional photonic crystal. Since a one-dimensional photonic crystal waveguide is used, the size and shape of the waveguide, the bending angle of the electromagnetic wave, etc. can be freely designed. As a result, integration can be realized and a more sophisticated laser generator can be realized. Also, the one-dimensional photonic crystal waveguide is a multilayer structure and can be easily manufactured.

[0043] In the configuration of the laser generator of the present invention, the exit-side photonic has an optical axis substantially perpendicular to the direction of the refractive index periodicity of the core of the excitation photonic crystal waveguide. The exit-side photonic crystal waveguide is formed of a photonic crystal having a refractive index periodicity in one direction, and has no refractive index periodicity on a Brillouin zone boundary in the direction. A photonic crystal waveguide having a core for propagating existing electromagnetic waves, wherein the photonic crystal waveguide is parallel to the direction having the refractive index periodicity of the core of the photonic crystal waveguide. Let n be the refractive index of the homogeneous medium in contact with the side of the core of the waveguide.

S1

The refractive index period of the core of the crystal crystal waveguide is a, the photonic crystal waveguide of the core

1

When the wavelength of electromagnetic waves propagating in the core is set to 01,

a / λ <1 / (2η)

1 01 SI

And the excitation mechanism includes two electrodes arranged with the excitation photonic crystal waveguide sandwiched from the direction of the refractive index periodicity of the core of the excitation photonic crystal waveguide, and the 2 A voltage source for applying a voltage between the two electrodes. By applying a voltage between the electrodes, the excitation photonic crystal waveguide is excited to oscillate the laser light, and the oscillated laser light is incident on the emission-side photonic crystal waveguide Is preferred. According to this preferred example, a laser generator can be realized.

Further, in the configuration of the laser generator of the present invention, the excitation mechanism excites the excitation photonic crystal waveguide by irradiating the excitation photonic crystal waveguide with excitation light. It is preferable to oscillate laser light. According to this preferred example, a laser generator can be realized.

[0045] In this case, it is substantially perpendicular to the direction of irradiating the excitation light and substantially perpendicular to the direction of the refractive index periodicity of the core of the excitation photonic crystal waveguide. The output-side photonic crystal waveguide further includes a vertical optical axis, and the output-side photonic crystal waveguide is composed of a photonic crystal having a refractive index periodicity in one direction, and has the refractive index periodicity. A photonic crystal waveguide having a core that propagates electromagnetic waves present on a Brillouin zone boundary in a direction, wherein the photonic crystal waveguide is the refractive index of the core of the photonic crystal waveguide The refractive index of the homogeneous medium in contact with the side surface of the core of the photonic crystal waveguide parallel to the direction having periodicity is n, and the refractive index period of the core of the photonic crystal waveguide A, the photonic

When the wavelength in the vacuum of the electromagnetic wave propagating in the core of the S1 1 crystal waveguide is set to 01,

a / λ <l / (2n)

1 01 SI

The excitation mechanism causes the excitation light to enter the excitation photonic crystal waveguide from a direction substantially perpendicular to the direction of the refractive index periodicity of the core of the excitation photonic crystal waveguide. Irradiation excites the excitation photonic crystal waveguide to oscillate the laser beam, and the oscillated laser beam is preferably incident on the emission-side photonic crystal waveguide. According to this preferred example, a laser generator can be realized.

[0046] In this case, the excitation mechanism is further substantially perpendicular to the optical axis of the emission-side photonic crystal waveguide and the refraction of the core of the excitation photonic crystal waveguide. Two waveguides having an optical axis substantially perpendicular to a direction having a rate periodicity and spaced apart from the excitation photonic crystal waveguide and sandwiching the excitation photonic crystal waveguide Each of the two waveguides is made of a photonic crystal having a refractive index periodicity in one direction, and propagates an electromagnetic wave existing on the Brillouin zone boundary in a direction not having the refractive index periodicity. A photonic crystal waveguide having a core, wherein the photonic crystal waveguide is parallel to a direction having the refractive index periodicity of the core of the photonic crystal waveguide. N is the refractive index of the homogeneous medium in contact with the side surface of the core, and the refractive index period of the core of the photonic crystal waveguide is

S2

2

If the wavelength is

02

a / λ <1 / (2η)

2 02 S2

It is preferable to satisfy the following condition. According to this preferred example, a laser generator can be realized.

In this case, the emission photonic crystal waveguide further includes an emission-side photonic crystal waveguide having an optical axis substantially perpendicular to the direction of the refractive index periodicity of the core of the excitation photonic crystal waveguide. The side photonic crystal waveguide is a photonic crystal composed of a photonic crystal having a refractive index periodicity in one direction, and having a core for propagating an electromagnetic wave existing on the Brillouin zone boundary in a direction not having the refractive index periodicity. The photonic crystal waveguide is formed on a side surface of the core of the photonic crystal waveguide parallel to a direction having the refractive index periodicity of the core of the photonic crystal waveguide. N is the refractive index of the contacting homogeneous medium and n is the refractive index of the core of the photonic crystal waveguide.

S1

A in a vacuum of electromagnetic waves propagating through the core of the photonic crystal waveguide

1

If the wavelength at is 01,

a / λ <1 / (2η)

1 01 SI

And the excitation photonic crystal waveguide sandwiches the core of the excitation photonic crystal waveguide from the direction having the refractive index periodicity of the core of the excitation photonic crystal waveguide, and A clad having a refractive index periodicity in the same direction as the direction having the refractive index periodicity of the core of the nick crystal waveguide; The excitation mechanism irradiates the excitation photonic crystal waveguide by irradiating the excitation photonic crystal waveguide with the excitation light from a direction having the refractive index periodicity of the core of the excitation photonic crystal waveguide. Preferably, the laser beam is excited to oscillate, and the oscillated laser beam is preferably incident on the emission-side photonic crystal waveguide. According to this preference! / Example, a laser generator can be realized.

[0048] In this case, the excitation mechanism further includes an optical axis along a direction having the refractive index periodicity of the core of the excitation photonic crystal waveguide, and the excitation photonic crystal guide It is preferable to have a light incident portion that is spaced apart from the waveguide. According to this preferred example, a laser generator can be realized.

Further, in this case, it is preferable that the light incident portion includes an optical waveguide and a lens that emits light from the optical waveguide. According to this preferred example, a laser generator can be realized.

[0050] Also, in this case, the excitation mechanism is configured so that the excitation photonic crystal waveguide from a direction substantially perpendicular to the direction of the core of the excitation photonic crystal waveguide having the refractive index periodicity. By irradiating the excitation light to the excitation photonic crystal waveguide, the excitation photonic crystal waveguide is excited to oscillate the laser light, and from the excitation photonic crystal waveguide, the refraction of the core of the excitation photonic crystal waveguide The oscillated laser beam is preferably emitted in a direction having a rate periodicity. According to this preferable example, the waveguide for propagating the excitation light can be arranged on the substrate. For this reason, it is sufficient that the waveguide is also a photonic crystal waveguide, which facilitates the production of the laser generator.

[0051] In this case, the excitation mechanism further includes an optical axis substantially perpendicular to the direction of the refractive index periodicity of the core of the excitation photonic crystal waveguide, and the excitation photonic Two waveguides are disposed apart from the crystal waveguide and sandwich the excitation photonic crystal waveguide, and each of the two waveguides has a refractive index periodicity in one direction. And a photonic crystal waveguide having a core for propagating an electromagnetic wave existing on a Brillouin zone boundary in a direction not having the refractive index periodicity, wherein the photonic crystal waveguide is the photonic crystal waveguide. Of the core of the photonic crystal waveguide parallel to the direction of the refractive index periodicity of the core of the waveguide The refractive index of the homogeneous medium in contact with the side surface is n, and the core of the photonic crystal waveguide is

S1

The refractive index period of a, and the electromagnetic wave propagating in the core of the photonic crystal waveguide

1

When the wavelength in vacuum is estimated,

01

a / λ <1 / (2η)

1 01 SI

[0052] In the configuration of the laser generator of the present invention, a reflection layer of a distributed feedback resonator is disposed between the excitation photonic crystal waveguide and the emission side photonic crystal waveguide. It is preferable. According to this preferred example, a laser generator having wavelength selectivity can be realized.

Hereinafter, embodiments of the present invention will be specifically described with reference to the drawings.

First, light (electromagnetic wave) propagation and confinement conditions in the one-dimensional photonic crystal waveguide that forms the basic structure of the present embodiment will be described.

FIG. 1 is a cross-sectional view showing a configuration of a one-dimensional photonic crystal. In Fig. 1, the light propagation direction is the Z-axis direction, the directions perpendicular to the light propagation direction (Z-axis direction) and perpendicular to each other are the X-axis direction and the Y-axis direction. And The photonic crystal 101 is a one-dimensional photonic crystal having a refractive index periodicity only in the Y-axis direction. A material 105a and a material 105b are alternately stacked in the Y-axis direction to form a multilayer structure. The thickness (length in the Y-axis direction) of the material 105a is t, and the refractive index of the material 105a is n. Also, the thickness of substance 105b (

A A

The length in the Y-axis direction is t, and the refractive index of the substance 105b is n. Photonic crystal 101

B B

It is a multilayer structure having a period (refractive index period) a in which the material 105a and the substance 105b are alternately laminated. Note that the period a is (t + t).

A B

In FIG. 1, a photonic crystal 101 is a core, and air (not shown) around the photonic crystal 101 is a clad, and the core and the clad constitute an optical waveguide. When a plane wave having a wavelength of λ in vacuum is incident as incident light 102 from an end surface (incident side end surface) 101a perpendicular to the Z-axis direction, which is the incident end of the photonic crystal 101,

0

The incident light 102 propagates in the photonic crystal 101 as propagating light 104. The propagating light 104 is transmitted from the end face (exit-side end face) 101b which is the exit end opposite to the entrance end to the exit light 103. And emitted. How the propagating light 104 propagates in the multilayer film of the substance 105a and the substance 105b in the photonic crystal 101 can be known by calculating a photonic band and illustrating it. The method for calculating the band of the photonic band is, for example, “Photonics rystals, Princeton University Press, (1995)”, Arima Takama, “Physical Review B, 19 91, 44 卷, 16, p.8565”. Are described in detail.

In the band calculation, the photonic crystal 101 shown in FIG. 1 has an infinite periodic structure in the Y-axis direction (stacking direction), and in the X-axis direction and the Z-axis direction (direction in which the layer surface spreads). Is assumed to be infinite. The contents obtained by band calculation will be described below. Since this band calculation is related to the photonic crystal 101 shown in FIG. 1, the content obtained by the band calculation will be described with reference to FIG.

FIG. 2 is a band diagram of the photonic crystal 101 shown in FIG. The conditions of the photonic crystal 101 at this time are as follows. First, substance 105a has a refractive index n of 2. 1011.

A

And its thickness t is t = 0 · 3a when expressed using the period a. In addition, substance 105b

A A

Has a refractive index n of 1 · 4578, and its thickness t is expressed as t = 0.7

B B B

a. FIG. 2 shows the results of band calculations in the Y-axis direction and the Z-axis direction of the photonic crystal 101, which is a multilayer structure having a period a in which the materials 105a and 105b are alternately stacked. FIG. 2 shows the first, second and third bands of TE-polarized light within the range of the first prior zone. Figure 2 connects the points where the normalized frequency co aZ2 7uc has the same value, and is contoured. Hereinafter, this contour line is referred to as “equal frequency line”. The suffix of each line represents the value of the standard frequency coaZ2 7uc. The standard frequency co aZ2 C is expressed using the angular frequency ω of the incident light 102, the period a of the multilayer structure, and the speed of light c in vacuum. The normalized frequency is the incident light

Using the wavelength of 102 in vacuum, it can also be expressed as aZ. Smell

0 0

The standardized frequency can be easily

Write 0.

In FIG. 2, the force in the Y-axis direction of the Brillouin zone in the photonic crystal 101 is 2 π Za. Since there is no periodicity in the Z-axis direction, the Brillouin zone in the lateral direction (Z-axis direction) There is no boundary, and it extends everywhere. TE polarized light is polarized light whose electric field direction is in the X-axis direction. Also, TM polarized light whose direction of magnetic field is polarized in the X-axis direction The band diagram is not shown. The band diagram for TM polarization is similar to the band diagram for TE polarization, but has a slightly different shape.

Here, the propagation when incident light is obliquely incident on the incident-side end face of the photonic crystal at an incident angle Θ will be examined.

FIG. 3 is a band diagram when incident light is obliquely incident on the incident side end face of the one-dimensional photonic crystal. As shown in Fig. 3, the photonic crystal bond band can be determined by drawing. Here, the one-dimensional photonic crystal is the photonic crystal 101 shown in FIG. 1, and FIG. 1 is also referred to. The incident angle Θ is an angle formed between the direction perpendicular to the incident side end face 101a, that is, the Z-axis direction and the traveling direction of the incident light 102. In addition, the inclination of the incident light 102 is limited to the YZ plane. Further, the incident side end face 101a of the photonic crystal 101 is perpendicular to the Z-axis.

[0062] Specifically, FIG. 3 shows a plane wave (polarized light) having a specific frequency a / λ from the end face 101a of the photonic crystal 101 in FIG. 1 with respect to the incident end face (incident face) 101a. Incident at an incident angle Θ

It is a band diagram when 0 I is applied. Note that the medium in contact with the end face (incident surface) 101a perpendicular to the Z-axis is a homogeneous medium having a different refractive index n.

h

In FIG. 3, the right side is a band diagram in the photonic crystal 101, and the left side is a band diagram of a homogeneous medium outside the photonic crystal 101. In FIG. 3, the upper part represents the coupling between the incident light 102 and the first band, and the lower stage represents the coupling between the incident light 102 and the second band. Since the incident light 102 has the homogeneous medium force also incident on the end face 101a, the band diagram of the incident light 102 is a band diagram in the homogeneous medium.

[0064] Here, the band diagram of the homogeneous medium is a sphere whose radius r is expressed by the following equation (in the YZ plane, a circle).

[0065] r = n-(a / λ)-(2 a)

h 0

Note that (2πΖ &) on the right side of the above equation is a coefficient for corresponding to the band diagram of the photonic crystal 101.

In the band diagram shown in FIG. 3, the traveling direction of propagating light propagating in the photonic crystal 101 is the normal direction of the equal frequency line. As shown in Fig. 3, the direction of propagating light propagating in the photonic crystal 101 is different in the first band and the second band. Neither is it in the Z-axis direction!

[0067] The band diagram of Fig. 3 will be specifically described. On the first and second bands, there are corresponding points 115 and 116 where the standard frequency aZ matches the incident light 102.

0

Within the tonic crystal 101, waves corresponding to each band propagate. The wave number vector of the incident light 102 is an arrow 110, and the wave vector of the propagating light is an arrow 113 (first band) and an arrow 114 (second band). In addition, the energy traveling direction of the first band of propagating light can be represented by an arrow 111, and the energy traveling direction of the second band of propagating light can be represented by the arrow 112, respectively.

[0068] Next, a case will be described in which both the first-band and second-band propagated light propagates in the Z-axis direction in the one-dimensional photonic crystal. FIG. 4 is a band diagram of the one-dimensional photonic crystal when the propagation directions of the propagation light of the first band and the second band are both in the Z-axis direction. In order to realize such propagation, specifically, the incident angle Θ is set so as to satisfy the condition of the following formula (1). Here, the one-dimensional photonic crystal is the photonic crystal 101 shown in FIG. Since the incident side end face 101a of the photonic crystal 101 is perpendicular to the Z-axis direction, which is the light propagation direction, “incident at an incident angle of 0” is inclined at an angle of 0 with respect to the Z-axis direction. The incident light is incident.

[0069] n-sin 0-(a / λ) = ± 0.5 (1)

h I 0

In the above formula (1), n is the refractive index of the medium in contact with the end face 101a of the photonic crystal 101.

h

is there.

When the incident light 102 is incident on the photonic crystal 101 at an incident angle 0 that satisfies the condition of the above formula (1), as shown in FIG. 4, the first and second on the Brillouin zone boundary 127 There is a propagation band. In Fig. 4, the wave number vector of incident light 102 is represented by arrow 120, and the energy traveling direction of propagating light 104 in photonic crystal 101 is represented by arrow 121 (first band) and arrow 122 (second band). Has been. Also, on the Brillouin zone boundary 127, the normalized frequency aZ 2 on the first and second bands

There are corresponding points 125 and 126 where 0 matches the incident light 10, respectively. The wave vector of the propagating light 104 is an arrow 123 (first band) and an arrow 124 (second band).

[0071] Due to symmetry at Brillouin zone boundary 127, the wave energy travels in the Z-axis direction Therefore, the propagating light 104 travels in the Z-axis direction. Here, the condition that the incident angle Θ to satisfy the propagation in the Z-axis direction satisfies the periodicity of the Brillouin zone in the Y-axis direction, for example,

n-sin 0-(a / λ) = ± 1. 0, ± 1. 5, ± 2. 0,

h I 0

However, as the value on the right side (absolute value) increases, n and Θ become larger values h I

This makes it difficult to implement.

FIG. 5 shows a band diagram on the Brillouin zone boundary in FIG. 4 limited to the Z-axis direction. In Fig. 5, the horizontal axis is the Z-axis direction component kz of the wave vector, and the vertical axis is the normalized frequency. When the wavelength of the incident light 102 in vacuum is λ,

0

The frequency value is determined by aZ. For this reason, as shown in FIG.

0

When the wavelength in the air is λ, it corresponds to each band in the photonic crystal 101.

0

Ζ axis components k and k of the wave vector. That is, the propagation light 104 is

1 2 1

= Z-axis direction inside photonic crystal 101 as wave of 2k and wavelength = 2k

1 2 2

Propagate to.

[0073] Here, the wavelength of light in a vacuum is propagated through the photonic crystal 101.

0

Wavelength of light (e.g., X, X

The value divided by 1 or 2) is defined as the “effective refractive index”. As can be seen from Fig. 5, in the propagation of propagating light existing on the Brillouin zone boundary, the effective refractive index varies greatly with λ. Left of line 128 (light line) with refractive power ^

0

The area on the side has an effective refractive index of less than 1, and the area to the right of line 128 (light line) has an effective index of refraction greater than 1. From Fig. 5, it can be seen that in the propagation of propagating light existing on the Brillouin zone boundary, the left side of the line 128 (light line), that is, the effective refractive index may be less than 1.

[0074] It is well known that the value obtained by differentiating the band curve shown in Fig. 5 with respect to kz (ie, the slope of the tangent) is the group velocity of propagating light. In Fig. 5, the slope of the tangent of the band curve decreases rapidly as the value of kz decreases, and when a / λ is the lower limit, the tangent of the band curve

0

The slope of the line (group velocity) is zero. This is a group velocity abnormality peculiar to the photonic crystal. The group velocity anomaly in the photonic crystal is extremely large and is opposite to the dispersion of the normal homogeneous material (the group velocity decreases as the wavelength of incident light increases). So this The waveguide can be used as an optical control element such as an optical delay element or a dispersion compensation element in optical communication. As shown in Fig. 5, on the Brillouin zone boundary, all the bands including the first band have “a large change in the effective refractive index due to wavelength” and “group velocity anomaly”. Such a waveguide that realizes propagation by a band on the Brillouin zone boundary can propagate light exhibiting the above characteristics with low loss, and thus can be applied to a light control element or the like. Note that the propagation light from the band on the Brillouin zone boundary forms a knotted electric field pattern, and is a kind of higher-order mode propagation light.

[0075] The present inventors have clarified several methods for coupling a plane wave outside the photonic crystal and propagating light on the Brillouin zone boundary propagating in the photonic crystal. . The methods for realizing “propagation on the Brillouin zone boundary” are disclosed in, for example, Japanese Patent Application Laid-Open No. 2003-215362, International Publication No. 04/81625, International Publication No. 04Z81626 and International Publication No. 05Z8305. It is disclosed. The light propagating in the photonic crystal is preferably single mode in order to prevent multimode dispersion of signals.

Next, light confinement in the one-dimensional photonic crystal 101 shown in FIG. 1 will be described.

First, light confinement to prevent leakage of light from the side surface (side surface parallel to the YZ plane) of the photonic crystal 101 in a direction along a plane perpendicular to the refractive index periodic direction. Explain the conditions. That is, the light confinement condition in the direction along the XZ plane of the photonic crystal 101 shown in FIG. 1 will be described. Thus, let us consider a case in which propagating light travels in a direction inclined by an angle φ with respect to the Z-axis direction in the photonic crystal 101 in the XZ plane. Fig. 6 is a schematic diagram showing the electric field when propagating light travels through the one-dimensional photonic crystal while tilting with respect to the Z-axis direction. As shown in FIG. 6, the periodic structure of the photonic crystal 101 is exposed when propagating light in the photonic crystal 101 travels in the XZ plane and is inclined with respect to the Z-axis direction. On the side surface 130 (side surface parallel to the YZ plane) 130, an electric field pattern shown as a pinecone-like pattern is generated. Specifically, electric field mountain 131 and electric field valley 132 are shown in FIG. Although not shown in the drawing, the medium serving as the cladding existing on the side surface of the photonic crystal 101 is a homogeneous medium having a different refractive index n. Therefore The side surface 130 where the periodic structure of the photonic crystal 101 is exposed has a uniform refractive index of n.

S

Touching the medium.

[0078] Using the period a of the photonic crystal 101, the characteristics of these electric fields will be described. As shown in FIG. 6, a wavefront having a period 133 is generated on the side of the homogeneous medium on the side face 130 exposed to the periodic structure that is in contact with the homogeneous medium. This wave can be leaking light. In Fig. 6, a right triangle consisting of auxiliary lines 134 and 135 perpendicular to each other and auxiliary line 136 (the hypotenuse) is formed. The lengths of auxiliary lines 134 and 135 are Z2cos φ and a Therefore, the size of the auxiliary line 136 can be obtained, and thus the size (length) of the period 133 can be easily obtained. Here, λ is the period of the propagation mode in the direction perpendicular to the axial direction.

[0079] That is, the magnitude of the period 133 is specifically:

Ά λ / cos φ) / {(λ / 2cos) + a}

It is expressed as Therefore, the period 133 has a refractive index n

S Wavelength in homogeneous media

This wave becomes leakage light when it is larger than XZn. Thus, a homogeneous medium with a refractive index n

O S S

The condition for the light propagating inside to not leak side force parallel to the YZ plane of the photonic crystal 101 is

X / n> a (λ / cos φ) / {\ λ / 2cos φ '+ a}

o s

Is to satisfy the following formula.

[0080] In addition, the size of the period 133 becomes the maximum value 2a when the angle φ is 90 °. In other words, if the following formula (2) is satisfied, no leakage light occurs regardless of the value of the angle φ.

[0081] λ Zn> 2a (2)

0 s

Also, the refractive index period of the photonic crystal 101 is a or a, and the photonic crystal 101

1 2

The side where the periodic structure is exposed (the side parallel to the YZ plane) 130 is the refractive index n or n

It is in contact with the SI S2 material and determines the wavelength of the propagating light in the photonic crystal 101 in vacuum.

01 or λ. In this case, if the following conditions similar to the above equation (2) are satisfied,

02

No light leaks regardless of the value of Φ.

[0082] λ Zn> 2a or / n> 2a

01 SI 1 02 S2 2

Note that if the above equation (2) is transformed into an equation including the normalized frequency aZ, a / λ <l / (2n) (3)

0 s

It can also be expressed as In other words, by satisfying the above equation (3), the light is completely confined on the side surface parallel to the YZ plane of the photonic crystal 101, and even if the propagating light is bent at a steep angle (steep angle), Light does not leak outside the nick crystal 101.

[0083] As in the above, this conditional expression is

a / λ <1 / (2η) or a / λ <1 / (2η)

1 01 SI 2 02 S2

It may be expressed as

Next, the confinement of light on the surface of the photonic crystal 101 that is perpendicular to the refractive index periodic direction will be described. That is, light confinement in the vertical direction (Y-axis direction) of the photonic crystal 101, that is, light confinement in a plane parallel to the XZ plane of the photonic crystal 101 will be described.

[0085] For example, if a medium having a refractive index smaller than the effective refractive index of the photonic crystal 101 is placed in contact with the upper and lower surfaces of the photonic crystal 101, the photonic crystal 101 is caused by the difference in refractive index. Light is confined inside. In order to confine light by the refractive index difference, the effective refractive index of the propagating light in the photonic crystal 101 must be large to some extent.

[0086] When the medium disposed in contact with the upper and lower surfaces of the photonic crystal 101 is, for example, air (refractive index: 1), light confinement is sufficient, but manufacturing becomes difficult. For this reason, light is often confined by a glass having a low refractive index (for example, quartz glass having a refractive index of 1.45). However, in this case, the refractive index of the medium disposed in contact with the upper and lower surfaces of the photonic crystal 101 is higher than that of air, so that the light can be confined. If the effect of “large change of effective refractive index with wavelength” or “group velocity anomaly”, which is a major feature of waveguides, is reduced, there is a problem.

[0087] In order to sufficiently confine light and to obtain the effects of "a large change in the effective refractive index with wavelength" and "group velocity anomaly", which are major features of the photonic crystal waveguide, Confinement using a band gap is effective. Hereinafter, light confinement in the vertical direction (Y-axis direction) of the photonic crystal 101 using the photonic band gap will be described. Figure 7 shows a photonic connection with a one-dimensional photonic crystal cladding and core. FIG. 7A is a cross-sectional view and FIG. 7B is a perspective view showing a configuration of a crystal waveguide. The photonic crystal waveguide 140 shown in FIGS. 7A and 7B is a one-dimensional photonic crystal having a refractive index periodicity in the same direction as the refractive index periodic direction, with the one-dimensional photonic crystal 101 shown in FIG. 1 as a core. In this configuration, a crystal clad 141 is provided. The clad 141 is provided so as to sandwich the photonic crystal 101 in the vertical direction (Y-axis direction). The clad 141 is configured by periodically and alternately laminating materials 105 a and 105 b constituting the photonic crystal 101 in the same direction as the refractive index periodic direction of the photonic crystal 101. That is, the clad 141 is made of the same material as the photonic crystal 101 and has a refractive index periodicity in the Y-axis direction. The period (refractive index period) b of the clad 141 is different from the period a of the photonic crystal 101.

[0088] Thus, the photonic crystal waveguide 140 is a one-dimensional photonic crystal, and is located in the refractive index period direction, where the refractive index period is the period b (cladding 141) and the period a. (A photonic crystal 101 that is a core), and a portion with a period a is sandwiched between places with a period b. It is possible to prevent light that can propagate through the photonic crystal 101 (core) from propagating in the clad 141 by the photonic band gap. Specifically, the values of the period a and the period b can be adjusted. Bho.

[0089] Theoretically, confinement of light in the vertical direction (Y-axis direction) is realized with photonic crystal 101 as the core by adjusting the values of period a and period b. be able to. However, the confinement action of the clad 141 may be weak, and when designing the actual photonic crystal waveguide 140, the practical upper limit of the period b of the clad 141, the period a Considering various conditions such as the interval of the value with the period b and the value of the period a of the photonic crystal 101 that is the core, it is necessary to make a configuration in which these are balanced. It is also possible to change the thickness ratio of each material composing the photonic crystal by setting the period a and the period b to the same value.

[0090] In addition, a photonic crystal comprising a clad 141 which is a one-dimensional photonic crystal by laminating a material different from the materials (substance 105a and substance 105b) constituting the core which is the one-dimensional photonic crystal 101 Also in the waveguide 140, confinement of light in the vertical direction (Y-axis direction) can be realized. In addition, the core or Can also confine light in the vertical direction (Y-axis direction) even in photonic crystal waveguides that form a clad and have three or more core or clad periods. In addition, the above-described methods for realizing light confinement in the Y-axis direction may be used alone or in combination.

[0091] As described above, the plane parallel to the XZ plane of the photonic crystal waveguide 140 can realize complete light confinement. Furthermore, if the photonic crystal waveguide 140 satisfies the above formula (3), light can propagate through the photonic crystal waveguide 140 with almost no loss. In addition, as described above, the photonic crystal waveguide 140 can easily propagate specific propagating light existing on the Brillouin zone boundary. Effects such as “group velocity abnormality” can be increased.

[0092] The photonic crystal waveguide 140 satisfying the above formula (3) can propagate specific propagating light existing on the Brillouin zone boundary. Furthermore, since the photonic crystal waveguide 140 can realize complete light confinement as described above and there is no limit on the size and shape thereof, when producing a waveguide element using this, High degree of design freedom. Further, since the photonic crystal waveguide 140 is a multilayer structure, it can be easily manufactured. For example, a multilayer film can be easily formed by laminating a multilayer film on a substrate, then forming a mask on the waveguide portion and performing etching. In order to enhance the durability, an overcladding such as quartz is put on the waveguide part to make it sealed.

[0093] The one-dimensional photonic crystal waveguide may be formed of a material generally used as a thin film material. As a material for the one-dimensional photonic crystal waveguide, for example, silica, silicon, titanium oxide, tantalum oxide, niobium oxide, magnesium fluoride, silicon nitride, etc., which are excellent in terms of durability and film formation cost, etc. Is suitable. These materials can be easily formed into thin films by general methods such as sputtering, vacuum deposition, ion-assisted deposition, and plasma CVD. Of these, both silica and tantalum oxide can polish the end face by the same method as glass, which enables high-light transmittance and uniform film formation without grain boundaries. t has the following characteristics.

[0094] When the one-dimensional photonic crystal waveguide is formed on a substrate, the material of the substrate In general, there is no particular limitation, and it is possible to use a general quartz or silicon substrate. The action of the one-dimensional photonic crystal waveguide is 200ηπ, which is the wavelength range of light normally used by selecting materials appropriately. It is demonstrated in the wavelength range of ~ 20 μm.

In addition, in the one-dimensional photonic crystal waveguide, the size of the incident side end surface and the emission side end surface can be set to, for example, 5 m × 5 m. Therefore, the optical field system of the collimator and the objective lens can match the mode field diameter of the optical fiber and the end face to increase the coupling efficiency.

[0096] In the following, waveguides that are various optical elements configured by using a plurality of one-dimensional photonic crystal waveguides having the same configuration as the photonic crystal waveguide 140 that satisfies the above formula (3). The element and the laser generator will be specifically described. In addition, such a waveguide

In the meantime, you can propagate electromagnetic waves other than light!

[0097] In all of the one-dimensional photonic crystal waveguides constituting the waveguide elements shown below, the propagation light existing on the Brillouin zone boundary is propagated. Also, these are the same configurations as the photonic crystal waveguide 140 that satisfies the above formula (3), and the plane (upper and lower planes) parallel to the XZ plane and the plane parallel to the YZ plane of the core photonic crystal 101 On the (side) side, complete light confinement is assumed.

[0098] Further, the specific method for coupling the plane wave outside the one-dimensional photonic crystal waveguide and the propagating light on the Brillouin zone boundary propagating in the one-dimensional photonic crystal waveguide has been described above. Since it is disclosed in the patent publication, its description is omitted.

[0099] [Embodiment 1]

A waveguide element according to the first embodiment of the present invention will be described with reference to the drawings. The waveguide element according to the first embodiment is perpendicular to the refractive index periodic direction and perpendicular to the signal light propagation direction in a part of the signal light waveguide through which the signal light propagates. This is a waveguide element that changes the refractive index of the resonance part by causing the control light to resonate, thereby causing a shift in the phase of the signal light. The waveguides used in this waveguide element are all one-dimensional photonic crystal waveguides.

FIG. 8 is a perspective view showing the configuration of the waveguide element in the first exemplary embodiment of the present invention.

FIG. 9 is a plan view showing the configuration of the waveguide element according to the first embodiment of the present invention. The As shown in FIGS. 8 and 9, the waveguide element 1 according to the first embodiment includes a substrate 2, a signal light waveguide (resonant photonic crystal waveguide) 3 provided on the substrate 2, and control light. An incident waveguide (resonance mechanism) 4 and a control light emission waveguide (resonance mechanism) 5 are provided. The signal light waveguide 3, the control light incidence waveguide 4, and the control light emission waveguide 5 are the above-described one-dimensional photonic crystal waveguides, respectively. As described above, the one-dimensional photonic crystal waveguide can propagate a specific higher-order mode light, and can further confine the propagation light.

[0101] The signal light waveguide 3, the control light incidence waveguide 4, and the control light emission waveguide 5 each have a stacking direction in the Y-axis direction, which is a direction perpendicular to the main surface of the substrate 2. It is a multilayer structure and has a refractive index periodicity in the stacking direction.

[0102] The optical axis of the signal light waveguide 3 is along the Z-axis direction. The optical axes of the control light incident waveguide 4 and the control light emitting waveguide 5 are the same, perpendicular to the optical axis (Z-axis direction) of the signal light waveguide 3, and in the stacking direction (Y-axis). Direction). That is, the optical axes of the control light incident waveguide 4 and the control light emitting waveguide 5 are along the X-axis direction. The control light incident waveguide 4 and the control light emitting waveguide 5 are disposed opposite to each other with the signal light waveguide 3 interposed therebetween. The exit side end face 4a of the control light incident waveguide 4 and the entrance side end face 5a of the control light exit waveguide 5 are located in the vicinity of the side face of the signal light waveguide 3. In the vicinity of the exit end face 4a of the control light entrance waveguide 4 and the entrance end face 5a of the control light exit waveguide 5, the width of the signal light waveguide 3 (the length in the X-axis direction) is another place. Compared to This is because this part is used as a resonator, so the width of this part (resonant part) is determined according to the resonance frequency, and the width cannot be reduced like other parts. is there . Depending on the resonance frequency, the width of the signal light waveguide 3 may be constant including the resonance portion, and the resonance portion may be narrower than other portions.

[0103] The signal light waveguide 3, the control light incident waveguide 4, and the control light emitting waveguide 5 are the photonic crystal waveguides 140 shown in FIGS. 7A and 7B, respectively. (3) is also satisfied. For this reason, leakage of propagating light on the Brillouin zone boundary in the direction along the plane perpendicular to the Y-axis direction which is the refractive index periodic direction does not occur. In the first embodiment, the refractive index n is 1 because each waveguide is air. Also mentioned above As described above, both the clad and the core are formed as one-dimensional photonic crystals so that propagation light does not leak on the Brillouin zone boundary in the stacking direction. Accordingly, in the signal light waveguide 3, the control light incident waveguide 4, and the control light emitting waveguide 5, the propagation light on the side surface and the upper and lower surface force Brillouin zone boundaries does not leak.

[0104] The distance between the side surface of the signal light waveguide 3 and the output side end surface 4a of the control light incident waveguide 4 is such that the evanescent wave of the control light 72 propagating in the control light incident waveguide 4 is The distance that can be coupled to the waveguide 3 for signal light. Similarly, the distance between the side surface of the signal light waveguide 3 and the incident-side end surface 5a of the control light emitting waveguide 5 is also a distance at which an evanescent wave can be coupled. The distance between the side surface of the signal light waveguide 3 and the output side end surface 4a of the control light incident waveguide 4 and the incident side end surface 5a of the control light output waveguide 5 is set in this way. Thus, the efficiency at which the evanescent wave is coupled, that is, the reflectance can be adjusted. Accordingly, the inner surface of the side surface of the signal light waveguide 3 functions as a resonator, and the control light 72 resonates in the X-axis direction in the signal light waveguide 3. That is, the control light incident waveguide 4, the control light emitting waveguide 5, and the signal light waveguide 3 constitute a Fabry-Perot resonator. The evanescent wave can be coupled in this way because the signal light waveguide 3 is the above-described one-dimensional photonic crystal waveguide, and the light is completely confined on the side surface.

[0105] Next, the operation of the waveguide element 1 of the first embodiment will be described.

A signal light 71 having a wavelength λ is propagated through the signal light waveguide 3. In this case, the signal light 71 is

S

Propagate to become a propagation mode on the Brillouin zone boundary.

Here, the control light 72 having the wavelength λ is propagated through the control light incident waveguide 4. Control light 72

C

Is also propagated in a propagation mode on the Brillouin zone boundary. As a result, the evanescent wave from the output-side end face 4a of the control light incident waveguide 4 is partially coupled to the signal light waveguide 3, and the rest is reflected. In addition, there is a slight gap between the side surface of the signal light waveguide 3 and the incident side end surface 5a of the control light emitting waveguide 5, so that the evanescent wave is partially coupled and the rest is reflected. . That is, the distance between the side surface of the signal light waveguide 3 and the incident side end surface 5a of the control light emitting waveguide 5 functions like a reflector. That is, a Fabry-Perot resonator is formed by the inside of the side surface of the signal light waveguide 3, and is formed in the signal light waveguide 3. Then, control light 73 resonating in the X-axis direction is generated. The resonating control light 73 is coupled to the control light emitting waveguide 5.

[0108] The distance between the side surface of the signal light waveguide 3 and the exit side end surface 4a of the control light incident waveguide 4 and the incident side end surface 5a of the control light exit waveguide 5 is specifically, It is determined by the characteristics of the control light and the resonance frequency. By adjusting the distance between the side surface of the signal light waveguide 3 and the output side end surface 4a of the control light incident waveguide 4 and the incident side end surface 5a of the control light output waveguide 5, the signal light guide is adjusted. The reflectance inside the side surface of the waveguide 3 can be adjusted.

By causing the control light 72 to resonate in the signal light waveguide 3, the electric field in the resonance portion becomes very strong, and a large nonlinear effect can be generated. Nonlinear effects occur in proportion to the square, cube (or higher) of the electric field. Therefore, a non-linear action occurs only in the resonance part of the control light 72, and the signal light 71 propagating through the part other than the resonance part is not affected at all. In order to generate the nonlinear effect, for example, the core of the signal light waveguide 3 may be configured to easily generate the nonlinear effect. For example, a nonlinear material is used for at least a part of the material constituting the core, a material such as a rare earth having a nonlinear action is doped in the material constituting the core, or a nonlinear action is applied to the material constituting the core. Increase the size of fine particles (quantum dots, etc.). By causing a non-linear effect, the refractive index changes, so the optical path length of the signal light 71 changes, and therefore the phase also changes. Since the wavelengths of the signal light 71 and the control light 72 are different, the control light 72 does not become noise of the signal light 71.

[0110] For example, the optical path length of the signal light 71 differs between the state in which the control light 72 is made to resonate and the state in which the control light 72 is not made to resonate. A phase shift occurs. Therefore, the waveguide element 1 can be used as a switching element, for example.

[0111] [Embodiment 2]

A waveguide element according to the second embodiment of the present invention will be described with reference to the drawings. The waveguide element according to the second embodiment is a waveguide element having a configuration including the waveguide element according to the first embodiment, and is a so-called Mach-Zehnder type optical path switching element. FIG. 10 is a perspective view showing the configuration of the waveguide element according to the second embodiment of the present invention. A waveguide element 6 shown in FIG. 10 includes the waveguide element of the first embodiment shown in FIGS. Therefore, in FIG. 10, members having the same functions as those shown in FIGS. 8 and 9 are denoted by the same reference numerals, and description thereof is omitted.

As shown in FIG. 10, the waveguide element 6 of the second embodiment includes a substrate 2 and a first signal light waveguide (resonant photonic crystal waveguide) 7a provided on the substrate 2. A signal light main waveguide 7, a control light incident waveguide 4, and a control light emitting waveguide 5 branched in the middle of the second signal light waveguide 7 b are provided. The signal light main waveguide 7, the control light incident waveguide 4 and the control light emitting waveguide 5 branched in the middle of the first signal light waveguide 7a and the second signal light waveguide 7b, respectively, This is a one-dimensional photonic crystal waveguide. As described above, the one-dimensional photonic crystal waveguide can propagate a specific higher-order mode light, and can further confine the propagation light.

[0114] The signal light main waveguide 7, the control light incident waveguide 4 and the control light emitting waveguide 5 branched in the middle of the first signal light waveguide 7a and the second signal light waveguide 7b are: Each is a multilayer structure in which the Y-axis direction, which is the direction perpendicular to the main surface of the substrate 2, is the stacking direction, and has a refractive index periodicity in the stacking direction.

[0115] The signal light main waveguide 7 is configured so that it splits into the first signal light waveguide 7a and the second signal light waveguide 7b on the way and separates them from each other. Be done!

[0116] After the first signal light waveguide 7a and the second signal light waveguide 7b are branched, the emission-side end face 4a faces the side surface of the first signal light waveguide 7a until it approaches again. Thus, the control light incident waveguide 4 is arranged. Similarly, after the first signal light waveguide 7a and the second signal light waveguide 7b are branched, the incident-side end face 5a is placed on the side surface of the first signal light waveguide 7a until it approaches again. Are arranged so as to face each other. That is, the control light incident waveguide 4 and the control light emitting waveguide 5 are disposed to face each other with the first signal light waveguide 7a interposed therebetween. Here, the first signal light waveguide 7a corresponds to the signal light waveguide 3 of the first embodiment shown in FIGS.

[0117] For signal light branched into the first signal light waveguide 7a and the second signal light waveguide 7b The main waveguide 7, the control light incidence waveguide 4, and the control light emission waveguide 5 are the photonic crystal waveguides 140 shown in FIGS. 7A and 7B, respectively, and also satisfy the above equation (3). . Therefore, no leakage of propagating light on the Prill-Ann zone boundary in the direction along the plane perpendicular to the Y-axis direction, which is the refractive index periodic direction, occurs. In the second embodiment, since the air around each waveguide is air, the refractive index n is 1. Also, as mentioned above,

S

Both the lad and the core are made as one-dimensional photonic crystals, so that the propagating light does not leak on the Brillouin zone boundary in the stacking direction. As a result, in the first signal light waveguide 7a and the second signal light waveguide 7b, the signal light main waveguide 7, the control light incident waveguide 4, and the control light emission waveguide 5 branched in the middle. , Side and vertical forces Propagation light on the Brillouin zone boundary will not leak.

[0118] Next, the operation of the waveguide element 6 of the second embodiment will be described.

The signal light 71 having the wavelength λ is propagated through the signal light main waveguide 7. In this case, signal light 71

S

Is propagated to be a propagation mode on the Brillouin zone boundary. The signal light 71 propagating through the signal light main waveguide 7 is branched and propagated to the first signal light waveguide 7a and the second signal light waveguide 7b.

C

Is also propagated in a propagation mode on the Brillouin zone boundary. As a result, a Fabry-Perot resonator having the inner surface of the side surface of the first signal light waveguide 7a as a resonance portion is configured, and the control light 72 resonates in the X-axis direction in the first signal light waveguide 7a. After resonating, the control light 72 is coupled to the control light emitting waveguide 5.

[0121] As explained in the first embodiment, the resonance portion of the control light 72 in the first signal light waveguide 7a is made to have a structure in which a nonlinear action is likely to occur. Occurs. Then, by causing the control light 72 to resonate in the first signal light waveguide 7a in this way, it is possible to cause a phase shift in the signal light 71 propagating through the first signal light waveguide 7a. .

On the other hand, in the second signal light waveguide 7b, the signal light 71 propagates without phase shift.

[0123] At the approaching point 9 where the first signal light waveguide 7a and the second signal light waveguide 7b approach each other. These distances are the distances at which the propagating light can be coupled by the evanescent wave to form a directional coupler. Because of this arrangement, either the first signal light waveguide 7a or the second signal light waveguide 7b is used as the signal light, depending on whether resonance is performed by the control light 72 or not. It is possible to control whether 71 is output.

As described above, in the waveguide element 6, resonance can be performed by the control light 72, or the branching direction of the signal light 71 can be controlled by a force that is not performed.

[0125] [Embodiment 3]

A waveguide element according to Embodiment 3 of the present invention will be described with reference to the drawings. The waveguide element of Embodiment 3 is perpendicular to the refractive index periodic direction and perpendicular to the signal light propagation direction in a part of the signal light waveguide through which the signal light propagates. The waveguide element is configured to resonate the control light and further resonate the signal light in its propagation direction. With such a configuration, transmission or reflection of signal light can be selected by resonance of control light. The waveguides used in this waveguide element are all one-dimensional photonic crystal waveguides.

FIG. 11 is a plan view showing the configuration of the waveguide element according to the third embodiment of the present invention.

A waveguide element 11 shown in FIG. 11 includes the waveguide element of the first embodiment shown in FIGS. Therefore, in FIG. 11, members having the same functions as those shown in FIGS. 8 and 9 are denoted by the same reference numerals, and description thereof is omitted.

As shown in FIG. 11, the waveguide element 11 of the third embodiment includes a substrate 2, an incident-side signal light waveguide 12, a signal resonance waveguide (resonance) provided on the substrate 2. Photonic crystal waveguide) 13, emission-side signal light waveguide 14, control light incident waveguide 4, and control light emitting waveguide 5. The incident-side signal light waveguide 12, the signal resonance waveguide 13, the output-side signal light waveguide 14, the control light incident waveguide 4, and the control light output waveguide 5 are each of the one-dimensional photonics described above. It is a crystal waveguide. As described above, the one-dimensional photonic crystal waveguide can propagate a specific higher-order mode light, and can further confine the propagation light.

The incident-side signal light waveguide 12, the signal resonance waveguide 13, the output-side signal light waveguide 14, the control-light incident waveguide 4, and the control-light output waveguide 5 are respectively formed on the substrate 2. Hanging on the main surface It is a multilayer structure with the Y-axis direction being the straight direction as the stacking direction, and has a refractive index periodicity in the stacking direction.

The optical axes of the incident-side signal light waveguide 12, the signal resonance waveguide 13, and the output-side signal light waveguide 14 are all along the axial direction. The incident-side signal light waveguide 12 and the outgoing-side signal light waveguide 14 are arranged so as to sandwich the signal resonance waveguide 13. In addition, the output-side end face 12a of the incident-side signal light waveguide 12 and the incident-side end face 14a of the output-side signal light waveguide 14 correspond to the incident-side end face 13a and the output-side end face 13b of the signal resonance waveguide 13, respectively. Located in the vicinity. The control light incident waveguide 4 and the control light emitting waveguide 5 are disposed to face each other with the signal resonance waveguide 13 interposed therebetween. The exit side end face 4a of the control light incident waveguide 4 and the entrance side end face 5a of the control light exit waveguide 5 are located in the vicinity of the side faces 13c and 13d of the signal resonance waveguide 13, respectively.

[0130] The incident-side signal light waveguide 12, the signal resonance waveguide 13, the output-side signal light waveguide 14, the control-light incident waveguide 4 and the control-light output waveguide 5 are shown in FIG. This is the photonic crystal waveguide 140 shown in FIG. 7B, which also satisfies the above equation (3). Therefore, no leakage of propagating light on the Brillouin zone boundary in the direction along the plane perpendicular to the Y-axis direction, which is the refractive index periodic direction, occurs. In the third embodiment, since the air around each waveguide is air, the refractive index n is 1. Also, as mentioned above, cladding and core

S

Both of these are made to be one-dimensional photonic crystals so that propagation light does not leak on the Brillouin zone boundary in the stacking direction. Thus, in the incident-side signal light waveguide 12, the signal resonance waveguide 13, the output-side signal light waveguide 14, the control light incident waveguide 4, and the control light output waveguide 5, the side surface and the vertical surface force The transmitted light on the Brillouin zone boundary does not leak.

[0131] The distances between the side surfaces 13c and 13d of the signal resonance waveguide 13 and the exit-side end face 4a of the control-light entrance waveguide 4 and the entrance-side end face 5a of the control-light exit waveguide 5 are as follows. Is a distance that resonates in the X-axis direction in the signal resonance waveguide 13. As a result, a Fabry-Perot resonator is formed in which the inner surfaces of the side surfaces 13c and 13d of the signal resonance waveguide 13 are resonant portions. The distance between the exit-side end face 12a of the incident-side signal light waveguide 12 and the incident-side end face 13a of the signal resonance waveguide 13 is the signal light propagating through the incident-side signal light waveguide 12. It is assumed that the 71 evanescent waves can be partially coupled to the signal resonance waveguide 13. The distance between the output-side end face 13b of the signal resonance waveguide 13 and the incident-side end face 14a of the output-side signal light waveguide 14 functions as an incomplete reflection surface due to partial coupling of the evanescent wave. The distance is such that the signal light 71 resonates in the Z-axis direction in the signal resonance waveguide 13. In other words, a Fabry-Perot resonator is formed in which the inner surfaces of the incident-side end face 13a and the emission-side end face 13b of the signal resonance waveguide 13 are resonant portions. As a result, signal light 74 that resonates in the Z-axis direction is generated in the signal resonance waveguide 13. The signal light 74 that resonates is coupled to the output-side signal light waveguide 14.

[0132] Next, the operation of the waveguide element 11 of the third embodiment will be described.

The signal light 71 having the wavelength λ is propagated through the incident-side signal light waveguide 12. In this case, the signal light 71 is propagated so as to be in a propagation mode on the Brillouin zone boundary. The signal light 71 propagating in the incident-side signal light waveguide 12 is coupled to the signal resonance waveguide 13, resonates in the signal resonance waveguide 13, and enters the output-side signal light waveguide 14. Join. That is, the signal light 71 having the resonance frequency in the signal resonance waveguide 13 is transmitted from the incident-side signal light waveguide 12 through the signal resonance waveguide 13 and propagates to the emission-side signal light waveguide 14. . However, even if signal light other than the wavelength λ is propagated to the incident-side signal light waveguide 12, the signal light does not resonate in the signal resonance waveguide 13, but is reflected by the signal resonance waveguide 13. Return to the incident-side signal light waveguide 12.

Here, when the control light 72 having a wavelength is resonated in the X-axis direction between the side surfaces 13c and 13d of the signal resonance waveguide 13, the refractive index of the signal resonance waveguide 13 is increased by a non-linear action. Change. As a result, the signal light 71 having the wavelength λ does not resonate in the signal resonance waveguide 13 but is reflected by the signal resonance waveguide 13 and returns to the incident-side signal light waveguide 12. Signal light of other wavelengths slightly different from the wavelength λ is transmitted through the signal resonance waveguide 13 s

It becomes like this.

As described above, the wavelength of the signal light transmitted through the signal resonance waveguide 13 can be selected depending on whether or not the control light 72 propagates. Therefore, the waveguide element 11 can be used as a switching element.

Note that, as described in the first embodiment, the control light 72 in the signal resonance waveguide 13 is shared. Desirably, the vibration part should be structured so that non-linear effects are likely to occur.

[Embodiment 4]

A waveguide element according to Embodiment 4 of the present invention will be described with reference to the drawings. Like the waveguide element of the third embodiment, the waveguide element of the fourth embodiment is perpendicular to the refractive index periodic direction in a part of the signal light waveguide through which the signal light propagates. The waveguide element is configured to resonate the control light in a direction perpendicular to the propagation direction of the signal light and further resonate the signal light in the propagation direction. The difference from the waveguide element of the third embodiment is that the propagation directions of signal light and control light are the same. With such a configuration, it is possible to select transmission or reflection of signal light by resonance of control light. The waveguides used in this waveguide element are all one-dimensional photonic crystal waveguides.

FIG. 12 is a plan view showing the configuration of the waveguide element according to the fourth embodiment of the present invention.

A waveguide element 16 shown in FIG. 12 has a configuration in which the control light incident waveguide 4 and the control light emitting waveguide 5 are removed from the waveguide element 11 of the third embodiment shown in FIG. Therefore, in FIG. 12, members having the same functions as those shown in FIG. 11 are given the same reference numerals, and descriptions thereof are omitted.

As shown in FIG. 12, the waveguide element 16 of the fourth embodiment includes the substrate 2 and the incident-side signal light waveguide 12, the signal resonance waveguide 13, and the waveguide provided on the substrate 2. And an output-side signal light waveguide 14. The incident-side signal light waveguide 12, the signal resonance waveguide 13, and the emission-side signal light waveguide 14 are the above-described one-dimensional photonic crystal waveguides, respectively. As described above, the one-dimensional photonic crystal waveguide can propagate a specific higher-order mode light, and can further confine the propagation light.

The incident-side signal light waveguide 12, the signal resonance waveguide 13, and the output-side signal light waveguide 14 are the photonic crystal waveguides 140 shown in FIGS. 7A and 7B, respectively. Equation (3) is also satisfied. For this reason, leakage of propagating light on the Brillouin zone boundary in the direction along the plane perpendicular to the Y-axis direction which is the refractive index periodic direction does not occur. In the third embodiment, since the air around each waveguide is air, the refractive index n is 1. Also

S

As mentioned above, both the cladding and the core are one-dimensional photonic crystals, and the stacking direction There is no leakage of propagating light on the Brillouin Zone boundary! As a result, the propagation light on the side and upper / lower surface Brillouin zone boundaries does not leak through the incident-side signal light waveguide 12, the signal resonance waveguide 13, and the output-side signal light waveguide 14.

Next, the operation of the waveguide element 16 according to the fourth embodiment will be described.

[0142] The signal light 71 having the wavelength λ is propagated through the incident-side signal light waveguide 12. In this case, the signal

S

Light 71 propagates in a propagation mode on the Brillouin zone boundary. The signal light 71 propagating in the incident-side signal light waveguide 12 is coupled to the signal resonance waveguide 13, resonates in the signal resonance waveguide 13, and enters the output-side signal light waveguide 14. Join. That is, the signal light 71 having the resonance frequency in the signal resonance waveguide 13 is transmitted from the incident-side signal light waveguide 12 through the signal resonance waveguide 13 and propagates to the emission-side signal light waveguide 14. .

Here, the control light 72 having the wavelength λ is propagated to the incident-side signal light waveguide 12 to cause signal resonance.

C

When coupled to the signal waveguide 13 and resonated in the X-axis direction between the side surfaces 13c and 13d of the signal resonance waveguide 13, the refractive index of the signal resonance waveguide 13 changes due to the nonlinear effect. As a result, the signal light 71 having the wavelength λ does not resonate in the signal resonance waveguide 13, and the signal resonance guide is not generated.

S

The light is reflected by the waveguide 13 and returns to the incident-side signal light waveguide 12. In the fourth embodiment, the incident-side signal light waveguide 12 and the emission-side signal light waveguide 14 are used as a resonance mechanism for causing resonance in the resonance waveguide 13.

As described above, the wavelength of the signal light transmitted through the signal resonance waveguide 13 can be selected depending on whether the control light 72 is propagated. Therefore, the waveguide element 16 can be used as a switching element.

It should be noted that, as described in the first embodiment, it is desirable that the resonance portion of the control light 72 in the signal resonance waveguide 13 has a structure in which a nonlinear action is likely to occur.

In FIG. 12, the shape of the signal resonance waveguide 13 is a rectangular parallelepiped, but the shape of the signal resonance waveguide 13 is not limited to a rectangular parallelepiped. Actually, it is desirable that the signal resonance waveguide 13 has a shape optimized so as to obtain desired resonance characteristics.

[Embodiment 5] A waveguide element according to the fifth embodiment of the present invention will be described with reference to the drawings. The waveguide element of the fifth embodiment changes the refractive index of the resonance portion by resonating the control light in the direction of the refractive index period in a part of the signal light waveguide through which the signal light propagates. It is a waveguide element configured to cause a shift in the phase of signal light. The waveguides used in this waveguide element are all one-dimensional photonic crystal waveguides.

FIG. 13 is a perspective view showing the configuration of the waveguide element according to the fifth embodiment of the present invention.

In FIG. 13, members having the same functions as those shown in FIGS. 8 and 9 of the first embodiment are denoted by the same reference numerals, and description thereof is omitted.

As shown in FIG. 13, the waveguide element 17 according to the fifth embodiment includes a substrate 2, a signal light waveguide 3 provided on the substrate 2, and a control light incident optical fiber (resonance mechanism). ) 18 and a control light incident lens 19 (resonance mechanism). The control light incident optical fiber 18 and the control light incident lens 19, which are the light incident portions, of the signal light waveguide 3 are configured so that the control light 72 can be radiated to the upper surface of the signal light waveguide 3 by force. It is arranged above. The signal light waveguide 3 is the above-described one-dimensional photonic crystal waveguide. As described above, the one-dimensional photonic crystal waveguide can propagate specific higher-order mode light, and can further confine the propagation light.

[0150] The signal light waveguide 3 is a multilayer structure in which the Y-axis direction, which is the direction perpendicular to the main surface of the substrate 2, is the stacking direction, and has a refractive index periodicity in the stacking direction.

[0151] The optical axis of the signal light waveguide 3 is along the Z-axis direction. The optical axes of the control light incident optical fiber 18 and the control light incident lens 19 are both along the stacking direction (Y-axis direction) of the signal light waveguide 3.

The signal light waveguide 3 is the photonic crystal waveguide 140 shown in FIGS. 7A and 7B, and also satisfies the above equation (3). For this reason, the leakage of propagating light on the Brillouin zone boundary in the direction along the plane perpendicular to the Y-axis direction which is the refractive index periodic direction does not occur. In the fifth embodiment, since the periphery of the signal light waveguide 3 is air, the refractive index n

S

Is 1. In addition, as described above, both the cladding and the core are made of a one-dimensional photonic crystal so that propagating light does not leak on the Brillouin zone boundary in the stacking direction. Thus, in the signal light waveguide 3, the Brillouin from the side surface and the top and bottom surfaces The propagating light on the zone boundary will not leak.

The distance between the upper surface of the signal light waveguide 3 and the control light incident lens 19 propagates through the control light incident optical fiber 18 and is collected by the control light incident lens 19 to be used for signal light. The distance at which the control light 72 irradiated on the upper surface of the waveguide 3 forms a condensing spot in the signal light waveguide 3 is defined as a distance. As a result, the clad on the upper and lower surfaces of the signal light waveguide 3 functions as a reflector, and a Fabry-Perot resonator in which the control light 72 resonates in the Y-axis direction is configured.

[0154] Next, the operation of the waveguide element 17 of the fifth embodiment will be described.

The signal light 71 having the wavelength λ is propagated through the signal light waveguide 3. In this case, the signal light 71 is

S

Propagate to become a propagation mode on the Brillouin zone boundary.

Here, the control light 72 having the wavelength λ is propagated through the control light incident optical fiber 18. Control light

C

The control light 72 from the incident optical fiber 18 is collected by the control light incident lens 19 and coupled to the signal light waveguide 3. Since the upper and lower surfaces of the signal light waveguide 3 are confined as described above, the inner sides of the upper and lower surfaces of the signal light waveguide 3 function like a reflector. Therefore, a Fabry-Perot resonator is formed by the inside of the upper and lower surfaces of the signal light waveguide 3, and the control light 73 that resonates in the axial direction is generated in the signal light waveguide 3.

[0157] By causing the control light 72 to resonate in the signal light waveguide 3, the electric field in the resonance portion becomes very strong. As described in the first embodiment, by setting the resonance portion of the control light 72 in the signal light waveguide 3 to have a structure in which a nonlinear action is likely to occur, a nonlinear action occurs only in this resonance portion. By causing a non-linear effect, the refractive index and the like change, so that the optical path length of the signal light 71 changes, and for example, the characteristics of the signal light 71 such as the phase also change.

For example, a phase shift occurs between the state in which the control light 72 is resonated and the state in which the control light 72 is not resonated because the optical path length of the signal light 71 is different as described above. Therefore, the waveguide element 17 can be used as a switching element, for example.

[0159] In addition, it is desirable that a cladding, which is a one-dimensional photonic crystal, be formed on the upper and lower surfaces of the core for use as a reflector.

[Embodiment 6] A waveguide element according to the sixth embodiment of the present invention will be described with reference to the drawings. The waveguide element of the sixth embodiment is a waveguide element having a configuration including the waveguide element of the fifth embodiment, and is a so-called Mach-Zehnder type optical path switching element.

FIG. 14 is a perspective view showing the configuration of the waveguide element according to the sixth embodiment of the present invention.

A waveguide element 21 shown in FIG. 14 includes the waveguide element of the fifth embodiment shown in FIG. Therefore, in FIG. 14, members having the same functions as those shown in FIG. 13 are denoted by the same reference numerals, and description thereof is omitted. Further, the signal light main waveguide 7 which is a waveguide through which the signal light 71 propagates in the waveguide element 21 of the sixth embodiment is the same as the signal light 71 in the waveguide element 6 of the second embodiment shown in FIG. The configuration is the same as the main waveguide 7 for signal light propagating. Therefore, in FIG. 14, members having the same functions as those shown in FIG. 10 are denoted by the same reference numerals, and description thereof is omitted.

As shown in FIG. 14, the waveguide element 21 of the sixth embodiment includes a substrate 2, a first signal light waveguide 7 a and a second signal light waveguide provided on the substrate 2. A signal light main waveguide 7 branched to 7b, a control light incident optical fiber 18, and a control light incident lens 19 are provided. The control light incident optical fiber 18 and the control light incident lens 19, which are the light incident portions, are arranged so that the control light 72 can be irradiated toward the upper surface of the first signal light waveguide 7 a. It is placed above 7a.

Next, the operation of the waveguide element 21 according to the sixth embodiment will be described.

[0164] The signal light 71 having the wavelength λ is propagated through the main waveguide 7 for signal light. In this case, signal light 71

S

C

The control light 72 from the incident optical fiber 18 is collected by the control light incident lens 19 and coupled to the first signal light waveguide 7a. As a result, a Fabry-Perot resonator is formed in which the inner surfaces of the upper and lower surfaces of the first signal light waveguide 7a are resonant portions, and the control light 72 is placed in the Y-axis direction in the first signal light waveguide 7a. Resonates.

As described in the first embodiment, the resonance of the control light 72 in the first signal light waveguide 7a By setting the portion to have a structure in which a non-linear action is likely to occur, a non-linear action occurs only in this resonance portion. Thus, by causing the control light 72 to resonate in the first signal waveguide 7a, a phase shift can be caused in the signal light 71 propagating through the first signal light waveguide 7a.

On the other hand, in the second signal light waveguide 7b, the signal light 71 propagates without being out of phase.

[0168] At the approaching point 9 where the first signal light waveguide 7a and the second signal light waveguide 7b approach each other, these distances are the distances at which the propagating light can be coupled by the evanescent wave. Form a coupler. Because of this arrangement, either the first signal light waveguide 7a or the second signal light waveguide 7b is used as the signal light, depending on whether resonance is performed by the control light 72 or not. It is possible to control whether 71 is output.

As described above, in the waveguide element 21, resonance can be performed by the control light 72, or the branching direction of the signal light 71 can be controlled by a force that is not performed.

[Embodiment 7]

A waveguide element according to the seventh embodiment of the present invention will be described with reference to the drawings. The waveguide element according to the seventh embodiment is an optical path switching element similarly to the waveguide element according to the sixth embodiment. The waveguides used in this waveguide element are all one-dimensional photonic crystal waveguides.

FIG. 15 is a perspective view showing the configuration of the waveguide element according to the seventh embodiment of the present invention.

The waveguide element 22 shown in FIG. 15 further includes a signal light main waveguide 7c in addition to the waveguide element 21 of the sixth embodiment shown in FIG. Instead of the lens 19, a VCSEL (Vertical Cavity Surface Emitting Lasers) 23 in which a plurality of laser elements (resonance mechanisms) 24 are arranged is added. Therefore, in FIG. 15, members having the same functions as those shown in FIG. 14 are denoted by the same reference numerals, and description thereof is omitted.

As shown in FIG. 15, the waveguide element 22 of the seventh embodiment includes a substrate 2, signal light main waveguides 7 and 7 c provided on the substrate 2, and a VCSEL 23. The signal light main waveguide (resonant photonic crystal waveguide) 7c has substantially the same configuration as the signal light main waveguide 7, and the first signal The light is branched to the signal waveguide 7d and the second signal light waveguide 7e. The VCSEL 23 is disposed above the signal light main waveguides 7 and 7c. The VCSEL 23 includes a plate-like portion 25, and a plurality of laser elements 24 are arranged on the surface of the plate-like portion 25 on the substrate 2 side. Light emitted from these laser elements 24 is control light. Control light from the laser element 24 is emitted in a direction perpendicular to the plate-like portion 25. Note that the VCSEL 23 can selectively emit control light from an arbitrary laser element 24.

[0173] Also in the signal light main waveguide 7c, the first signal waveguide 7d and the second signal waveguide 7e, which are the same as the approaching portion 9 of the signal light main waveguide 7, propagate through each other. An approaching point (directional coupler) 9c having an interval that is affected by the evanescent wave of propagating light is provided.

[0174] With such a configuration, it is possible to irradiate control light to any location on the upper surfaces of the signal light main waveguide 7 and the signal light main waveguide 7c. In other words, the control light can resonate at an arbitrary position of the signal light main waveguide 7 and the signal light main waveguide 7c. Therefore, the phases of the signal light 71 and the signal light 71c incident on the signal light main waveguide 7 and the signal light main waveguide 7c can be shifted at desired positions. Therefore, if the waveguide element 22 is used, the control light is emitted from an arbitrary laser element 24, and thereby the signal light 71 and the signal light 71c propagated in the signal light main waveguide 7 and the signal light main waveguide 7c, respectively. The optical path can be switched.

[0175] As described above, in the waveguide element 22, the waveguide circuits of the signal light 71 and the signal light 71c are integrated, and the light source of the control light is arranged in an array. Therefore, by selecting the irradiation pattern, it is possible to perform a more complicated optical path conversion process of the signal lights 71 and 71c. Instead of VCSEL23, optical fibers arranged in an array can be used!ヽ.

Note that the signal light main waveguide 7 and the signal light main waveguide 7c may be used instead of a more complex waveguide. Even in this case, the one-dimensional photonic crystal waveguide may be used.

[Embodiment 8]

A waveguide element according to the eighth embodiment of the present invention will be described with reference to the drawings. 16A and 16B show the configuration of the waveguide element according to the eighth embodiment of the present invention, and It is a top view which shows an optical path. FIG. 16A shows a state in which signal light is emitted in the middle of the output waveguide force, and FIG. 16B shows a state in which signal light is emitted at the end of the output waveguide force.

As shown in FIGS. 16A and 16B, the waveguide element 26 according to the eighth embodiment includes a substrate 2 and an S-shaped waveguide (resonant photonic crystal waveguide) 27 provided on the substrate 2. And VCSEL23. The VCSEL 23 is disposed above a part of the slab-shaped portion of the S-shaped waveguide 27, and a plurality of laser elements 24 (see FIG. 15) are arranged on the surface on the substrate 2 side. The S-shaped waveguide 27 is the one-dimensional photonic crystal waveguide described above. As described above, the one-dimensional photonic crystal waveguide can propagate a specific higher-order mode light, and can further confine the propagation light.

The S-shaped waveguide 27 is a multilayer structure in which the Y-axis direction that is perpendicular to the main surface of the substrate 2 is the stacking direction, and has a refractive index periodicity in the stacking direction.

[0180] The S-shaped waveguide 27 is wider than the incident waveguide 28, ie, spreads in a direction parallel to a plane perpendicular to the stacking direction (Y-axis direction). Slab waveguide (slab-like portion) 30 and three output waveguides 29 are provided. The incident waveguide 28 is connected to the slab waveguide 30. The slab waveguide 30 is formed in an S shape as shown in FIGS. 16A and 16B. Further, the three output waveguides 29 are also connected to the slab waveguide 30. The three output waveguides 29 are arranged in parallel.

[0181] The S-shaped waveguide 27 including the incident waveguide 28, the slab waveguide 30, and the emission waveguide 29 is the photonic crystal waveguide 140 shown in FIGS. 7A and 7B, respectively. The above equation (3) is also satisfied. For this reason, leakage of propagating light on the Brillouin zone boundary in the direction along the plane perpendicular to the Y-axis direction which is the refractive index periodic direction does not occur. In the eighth embodiment, since the air around the S-shaped waveguide 27 is air, the refractive index n is 1.

S

The In addition, as described above, both the cladding and the core are made to be one-dimensional photonic crystals so that the propagation light does not leak on the Brillouin zone boundary in the stacking direction. As a result, in the S-shaped waveguide 27, the propagation light on the Brillouin zone boundary does not leak in the side surface and the vertical surface force.

Next, the operation of the waveguide element 26 according to the eighth embodiment will be described. Incident light 76 is propagated through the incident waveguide 28. In this case, the incident light 76 is propagated in a propagation mode on the Brillouin zone boundary. Incident light 76 enters the slab waveguide 30 from the incident waveguide 28. As described above, the slab waveguide 30 has complete confinement of light on the side surface. Accordingly, the propagating light 71a is concavely reflected by the inner side surface 30a of the slab waveguide 30 and becomes a wide luminous flux. Further, the propagating light 71a is collected by concave reflection at the inner side surface 30b of the slab waveguide 30 and is incident on one of the three output waveguides 29, and is output from the output waveguide 29. It is emitted as 78.

Here, by emitting control light from an arbitrary laser element 24 of the VCSEL 23, resonance in the Y-axis direction of the control light occurs in a part of the slab waveguide 30. Then, due to the nonlinear action, the refractive index of the resonant portion of the slab waveguide 30 changes, and the path of the propagating light 71a changes. As described in the first embodiment, the resonance part of the control light in the slab waveguide 30 has a structure in which a nonlinear action is likely to occur, so that the nonlinear action occurs only in this resonance part.

First, it is assumed that the path force of propagating light 71a is in a state as shown in FIG. 16A without emitting control light. That is, it is assumed that the propagating light 71a is emitted from the emission waveguide 29 arranged in the middle. Next, by emitting control light from an arbitrary laser element 24 of the VCSEL 23, a refractive index distribution in the spreading direction of the slab waveguide 30 is generated, and the traveling direction of the wave front is bent, for example, as shown in FIG. 16B. State. That is, the path of the propagation light 71a can be converted so that the propagation light 71a is emitted from the emission waveguide 29 arranged at the end. Thus, by selecting the laser element 24 that emits the control light, the emission waveguide 29 from which the propagating light 71a is emitted can be selected. It is also possible to prevent the propagating light 71a from being emitted from any of the emission waveguides 29. Note that the number of emission waveguides 29 and the number of laser elements 24 that emit control light are not limited at all.

[0186] In addition, since the resonance direction of the control light in the S-shaped waveguide 27 of the waveguide element 26 is the Y-axis direction, in the core of the S-shaped waveguide 27, the Y-axis direction that is the refractive index periodic direction The light must be confined in a direction along a plane perpendicular to the surface. Therefore, a cladding that is a one-dimensional photonic crystal is formed in the vertical direction of the core (Y-axis direction). It is desirable.

[Embodiment 9]

A waveguide element according to the ninth embodiment of the present invention will be described with reference to the drawings. The waveguide element according to the ninth embodiment is an optical amplification element. The waveguide element according to the ninth embodiment includes the first embodiment shown in FIGS. 8 and 9, the third embodiment shown in FIG. 11, the fourth embodiment shown in FIG. 12, and the embodiment shown in FIG. 5 and because the configuration is almost the same as the waveguide element in the embodiment 8 shown in FIGS. 16A and 16B, refer to FIGS. 8, 9, 11, 12, 13 and 16A and 16B. While explaining.

In the first, third, fourth, fifth and eighth embodiments, in order to increase the nonlinear action of the resonance part, for example, a nonlinear material is used for at least a part of the material constituting the core. ing. However, in the ninth embodiment, the material constituting the core is doped with a substance having an amplifying action in order to cause the resonance part to have an amplifying action rather than a non-linear action. Here, examples of the substance having an amplifying action include erbium and thulium. Further, powerful pump light is used as the control light. As a result, the waveguide elements 1, 11, 16, 17 and 26 function as amplification elements. Note that the waveguide element 26 has three output waveguides 29, but in the ninth embodiment, only one is required.

[0189] In the waveguide elements 1 and 17 and the waveguide elements 11 and 16, when the signal light 71 is propagated and the control light 72, which is a powerful pump light, is resonated, the electric field in the resonance part is very high. It will be strong. Since the resonance part is doped with a substance having an amplifying action, the signal light 71 is amplified and propagated to the signal light waveguide 3 and the output-side signal light waveguide 14.

[0190] In addition, in the waveguide element 26, when the control light, which is a strong pump light, is resonated while propagating the propagating light 71a, the electric field in the resonance portion becomes very strong. Since the resonance part is doped with a substance having an amplifying action, the propagating light 71 a is amplified and propagated to the emission waveguide 29. In the waveguide element 26, the VCSEL 23 is used to emit control light, which is pump light, so that pump light can be irradiated over a wide range. As a result, the total energy of the pump light can be increased, and the amplification factor can be increased. In this case, the refractive index distribution is generated as in the eighth embodiment, and the wavefront is There is no need to bend the direction of travel.

[0191] As described above, the waveguide element according to the ninth embodiment functions as an amplifying element and can be easily manufactured because of its simple configuration.

[Embodiment 10]

A laser generator according to the tenth embodiment of the present invention will be described with reference to the drawings. FIG. 17 is a perspective view showing the configuration of the laser generator in the tenth embodiment of the present invention. A laser generator 32 shown in FIG. 17 is configured such that the incident-side signal light waveguide 12 is removed from the waveguide element 11 of the third embodiment shown in FIG. In this configuration, a DFB portion 33 is provided that is formed by periodically forming cuts that are perpendicular to the direction. Therefore, in FIG. 17, members having the same functions as those shown in FIG. 11 are denoted by the same reference numerals, and the description thereof is omitted.

[0193] Specifically, the DFB section 33 is a reflective layer that selectively reflects a specific wavelength in a DFB (Distributed Feedback) resonator. This structure also has a refractive index periodicity in the optical axis direction (Z-axis direction). In other words, a plurality of one-dimensional photonic crystal waveguides are periodically arranged. Note that if the number of cuts in the DFB section 33 is too large, light does not propagate, so the number of cuts is adjusted to an optimum number.

In the waveguide element 11 of the third embodiment, for example, a nonlinear material is used as a material constituting the core of the signal resonance waveguide 13 so that a nonlinear action occurs in the signal resonance waveguide 13. It was. However, in the laser generator 32 of the tenth embodiment, the signal resonance waveguide 13 is used as an excitation photonic crystal waveguide, and the control light incident waveguide 4 and the control light emission waveguide 5 are used as an excitation mechanism. . The core of the signal resonance waveguide 13 may be configured using a laser medium. As the laser medium, for example, Nd-doped YAG (yttrium aluminum garnet crystal), glass, ruby, GaAs, InP, GaAlAs-P, InAs, etc. may be used. Alternatively, quantum media or pigments may be included in the core to form a laser medium.

[0195] The evanescent wave of the control light 72, which is the excitation light, is coupled to the signal resonance waveguide 13 by the control light incident waveguide 4, and the control light 72 is transmitted to the signal resonance waveguide 13 in the X-axis direction. To resonate. As a result, the signal resonance waveguide 13 is excited, and the laser light resonates (oscillates) in the Z-axis direction between the incident side end face 13a and the emission side end face 13b. Of the incident-side end face 13a and the outgoing-side end face 13b of the signal resonance waveguide 13, laser light is emitted from the outgoing-side end face 13b on the DFB portion 33 side, which has a low reflectance, and the laser is emitted from the outgoing-side signal light waveguide 14 Light 75 is emitted to the outside. The laser generator 32 has wavelength selectivity because the DFB section 33 is provided.

[Embodiment 11]

A laser generator according to the eleventh embodiment of the present invention will be described with reference to the drawings. FIG. 18 is a perspective view showing the configuration of the laser generator in Embodiment 11 of the present invention. The laser generator 36 shown in FIG. 18 is different from the laser generator 32 of the tenth embodiment shown in FIG. 17 in that the control light incident waveguide 4 and the control light emitting waveguide 5 are removed. This is a configuration in which a control light incident optical fiber 18 and a control light incident lens 19 are provided as an excitation mechanism. The control light incident optical fiber 18 and the control light incident lens 19 have the same functions as the control light incident optical fiber 18 and the control light incident lens 19 shown in FIG. Yes. Since the other configuration is substantially the same as that of the laser generator 32 of the tenth embodiment shown in FIG. 17, members having the same functions as those shown in FIG. 17 are denoted by the same reference numerals. The explanation is omitted.

The control light 72 that is the excitation light from the control light incident optical fiber 18 is collected by the control light incident lens 19 and coupled to the upper surface of the signal resonance waveguide 13. Then, the control light 72 resonates in the Y-axis direction in the signal resonance waveguide 13. As a result, the signal resonance waveguide 13 is excited, and the laser beam resonates (oscillates) in the Z-axis direction between the incident side end face 13a and the emission side end face 13b. Of the incident-side end face 13a and the outgoing-side end face 13b of the signal resonance waveguide 13, laser light is emitted from the outgoing-side end face 13b on the DFB portion 33 side, which has low reflectivity, and from the outgoing-side signal light waveguide 14 Laser light 75 is emitted to the outside. Since the laser generator 36 is provided with the DFB section 33, it has wavelength selectivity.

[0198] [Embodiment 12]

A laser generator according to Embodiment 12 of the present invention will be described with reference to the drawings. To do. FIG. 19 is a perspective view showing the configuration of the laser generator in Embodiment 12 of the present invention. In the laser generator 37 shown in FIG. 19, the control light incident waveguide 4 and the control light emitting waveguide 5 are removed from the laser generator 32 of the tenth embodiment shown in FIG. An electrode 38 and an electrode 39 are provided on the upper and signal resonance waveguides 13, respectively, and a voltage source 40 for applying a voltage between the electrode 38 and the electrode 39 is added. Therefore, in FIG. 19, members having the same functions as those shown in FIG. 17 are denoted by the same reference numerals, and description thereof is omitted. In the twelfth embodiment, the electrode 38, the electrode 39, and the voltage source 40 function as an excitation mechanism.

[0199] In the laser generator 37, an electrode 38 is provided on the substrate 2. Specifically, an electrode 38 is formed between the substrate 2, the signal resonance waveguide 13, the DFB portion 33, and the emission-side signal light waveguide 14. An electrode 39 is formed on the signal resonance waveguide 13. A voltage source 40 is connected between the electrodes 38 and 39, and a voltage can be applied between the electrodes 39 and 38.

[0200] By applying a voltage between the electrode 38 and the electrode 39 using the voltage source 40, the signal resonance waveguide 13 is excited, and the laser light is Z-axis between the incident side end face 13a and the output side end face 13b. Resonates (oscillates) in the direction. Of the incident side end face 13a and the emission side end face 13b of the signal resonance waveguide 13, laser light is emitted from the emission side end face 13b on the DFB portion 33 side having a low reflectance, and the laser is emitted from the emission side signal light waveguide 14 Light 75 is emitted to the outside. Since the laser generator 37 is provided with the DFB section 33, it has wavelength selectivity.

[0201] [Embodiment 13]

A laser generator according to the thirteenth embodiment of the present invention will be described with reference to the drawings. FIG. 20 is a perspective view showing the configuration of the laser generator in the thirteenth embodiment of the present invention. The laser generator 41 shown in FIG. 20 has substantially the same configuration as the waveguide element 16 of the fourth embodiment shown in FIG. Therefore, in FIG. 20, members having the same functions as those shown in FIG. 12 are given the same reference numerals, and descriptions thereof are omitted.

[0202] In the waveguide element 16 of the fourth embodiment, for example, a non-linear material is used as a material constituting the core of the signal resonance waveguide 13 so that a non-linear action occurs in the signal resonance waveguide 13. It was. However, in the laser generator 41 of the thirteenth embodiment, the signal resonance The waveguide 13 is used as an excitation photonic crystal waveguide. Therefore, for example, as described in the tenth embodiment, the core of the signal resonance waveguide 13 may be configured using a laser medium. In the thirteenth embodiment, the input-side signal light waveguide 12 and the output-side signal light waveguide 14 function as an excitation mechanism.

[0203] The evanescent wave of the control light 72, which is the excitation light, is coupled to the signal resonance waveguide 13 by the incident-side signal light waveguide 12, and the control light 72 is transmitted to the signal resonance waveguide 13 as Z Resonate in the axial direction. As a result, the signal resonance waveguide 13 is excited, and the laser light resonates (oscillates) in the Y-axis direction between the upper and lower surfaces of the signal resonance waveguide 13. Here, the light confinement by the clad on the upper surface of the signal resonance waveguide 13 is made weaker than the light confinement by the clad on the lower surface of the signal resonance waveguide 13, so that the laser light can be guided by the signal resonance waveguide. The light is emitted from the upper surface of the path 13.

[0204] [Embodiment 14]

A waveguide element according to the fourteenth embodiment of the present invention will be described with reference to the drawings. The waveguide element according to the fourteenth embodiment is a resonant element. FIG. 21 is a perspective view showing the configuration of the waveguide element according to the fourteenth embodiment of the present invention.

As shown in FIG. 21, the waveguide element 42 according to the fourteenth embodiment includes a substrate 2, an incident-side waveguide (incident-side photonic crystal waveguide) 43 provided on the substrate 2, and a resonance unit. (Resonant photonic crystal waveguide) 45 and output side waveguide (output side photonic crystal waveguide) 44. The incident-side waveguide 43, the resonance part 45, and the emission-side waveguide 44 are the above-described one-dimensional photonic crystal waveguides, respectively. As described above, the one-dimensional photonic crystal waveguide can propagate specific high-order mode light, and can further confine the propagation light.

[0206] The incident-side waveguide 43, the resonance unit 45, and the emission-side waveguide 44 are each a multilayer structure in which the Y-axis direction that is perpendicular to the main surface of the substrate 2 is the stacking direction. Refractive index Has periodicity.

The incident side waveguide 43 and the emission side waveguide 44 are linear. The incident-side waveguide 43 and the emission-side waveguide 44 are the photonic crystal waveguides 140 shown in FIGS. 7A and 7B, respectively, and also satisfy the above equation (3). Therefore, with respect to the Y-axis direction, which is the periodic direction of the refractive index The leakage of propagating light on the Brillouin zone boundary in the direction along the vertical plane does not occur. In Embodiment 14, since the circumference of each waveguide is air, the refractive index n is

S

1. In addition, as described above, both the cladding and the core are made of a one-dimensional photonic crystal so that propagating light does not leak on the Brillouin zone boundary in the stacking direction. Thereby, in the incident side waveguide 43 and the emission side waveguide 44, the propagation light on the Brillouin zone boundary does not leak even in the side surface and the upper and lower surface forces.

[0208] The resonating part 45 has a cylindrical shape. The resonating unit 45 has a structure in which a plurality of disk-like layers are stacked in the Y-axis direction, and the center axis direction of the circle is the refractive index periodic direction. In addition, light is completely confined on the side surface, which is the outer peripheral surface of the cylinder, and the upper and lower surfaces, which are circular.

[0209] The resonating unit 45, which is a cylindrical one-dimensional photonic crystal having such a configuration, functions as a resonator by coupling an evanescent wave from the side surface thereof. That is, only light of a predetermined frequency is coupled to the resonance unit 45 and resonates inside the resonance unit 45. Therefore, in the waveguide element 42, the distance between the incident-side waveguide 43 and the resonance part 45 and the distance between the resonance part 45 and the emission-side waveguide 44 are set to appropriate distances. Can be used as a resonant element.

[0210] Next, the operation of the waveguide element 42 according to the fourteenth embodiment will be described.

[0211] First, the resonating unit 45 is designed so that, for example, only light of wavelength λ resonates. Illustration

1

For example, the resonance part 45 having a desired resonance frequency is produced by changing the dimensions and shape thereof.

[0212] Then, the incident-side waveguide 43 includes a plurality of incident lights with different frequencies, including light of wavelength λ.

1

Propagate 76. In this case, the incident light 76 is propagated so as to be in a propagation mode on the Brillouin zone boundary. As a result, only the light of the wavelength resonates in the resonating part 45 and is emitted.

1

The light is coupled to the side waveguide 44 and emitted from the emission side waveguide 44 as selection light 77. The outgoing light 78 other than the selection light 77 is emitted from the outgoing side end face of the incident side waveguide 43. In other words, in the waveguide element 42, only light of a wavelength is transmitted from the incident side waveguide 43 to the output side waveguide 4.

1

Light other than that transmitted through 4 is emitted from the incident-side waveguide 43 without being coupled by the resonator 45. [0213] The number of columnar resonators having a one-dimensional photonic crystal structure may be increased. Specifically, a waveguide element having a structure shown in FIG. 22 may be used. FIG. 22 is a perspective view showing a configuration of a waveguide element having two stages of resonant portions according to the fourteenth embodiment of the present invention. As shown in FIG. 22, the waveguide element 42a includes two resonance parts, a resonance part 45 and a resonance part (resonant photonic crystal waveguide) 45a. Since the other configuration is the same as that of the waveguide element 42 shown in FIG. 21, members having the same functions as those shown in FIG. 21 are denoted by the same reference numerals, and description thereof is omitted. .

[0214] The resonance unit 45a has substantially the same configuration as the resonance unit 45. In this way, by providing two stages of the resonating part, the intensity of light in the frequency range to be transmitted can be made uniform, so that a so-called “flat top characteristic” can be realized.

[0215] In addition, the wavelength separation element can be configured by using a plurality of resonance units each having a different resonance frequency. Specifically, the configuration shown in FIG. FIG. 23 is a perspective view showing a configuration of a waveguide element that is a demultiplexing element in Embodiment 14 of the present invention. In FIG. 23, members having the same functions as those shown in FIG. 21 are given the same reference numerals, and descriptions thereof are omitted.

[0216] As shown in Fig. 23, the waveguide element 42b includes three resonance portions (resonant photonic crystal waveguides) 45b, 45c, and 45d each having a different resonance frequency. Further, the waveguide element 42b includes emission-side waveguides (emission-side photonic crystal waveguides) 44b, 44c, and 44d corresponding to the respective resonating portions 45b, 45c, and 45d. The waveguide element 42b has a configuration in which an incident-side waveguide 43, resonating portions 45b, 45c, and 45d and emission-side waveguides 44b, 44c, and 44d are disposed on the substrate 2.

[0217] The resonating parts 45b, 45c, and 45d are one-dimensional photonic crystal waveguides similarly to the resonating part 45 described above. In addition, the resonating parts 45b, 45c, and 45d resonate light of different wavelengths.

twenty three

It is designed to resonate with light of long λ.

Four

[0218] The resonating parts 45b, 45c, and 45d are arranged so as to be coupled to the incident-side waveguide 43, and the output-side waveguides 44b, 44c, and 44d are coupled to the resonating parts 45b, 45c, and 45d, respectively. Arranged to get. [0219] The incident-side waveguide 43 includes different wavelengths including light of a wavelength, light of a wavelength, and light of a wavelength.

2 3 4

A plurality of incident lights 76 having a plurality of wave numbers are propagated. In this case, the incident light 76 is propagated in a propagation mode on the Brillouin zone boundary. As a result, the light of the wavelength is

2

Within 45b, the light of the wavelength is in the resonator 45c, and the light of the wavelength is in the resonator 45d.

3 4

Resonate and are coupled to the output side waveguides 44b, 44c, and 44d, respectively, and are emitted from the output side waveguides 44b, 44c, and 44d as selection light 77. Further, the outgoing light 78 other than the selection light 77 is emitted from the outgoing side end face of the incident side waveguide 43. Thus, by using the waveguide element 42b, it is possible to selectively extract a plurality of light beams having desired wavelengths.

[0220] [Embodiment 15]

A waveguide element according to the fifteenth embodiment of the present invention will be described with reference to the drawings. The waveguide element in the fifteenth embodiment is a resonant element. FIG. 24 is a perspective view showing the configuration of the waveguide element according to the fifteenth embodiment of the present invention. The waveguide element 47 of the fifteenth embodiment has substantially the same configuration as the waveguide element 42 of the thirteenth embodiment shown in FIG. 21 except that the shape of the resonance part is different. Therefore, in FIG. 24, members having the same functions as those shown in FIG. 21 are given the same reference numerals, and descriptions thereof are omitted.

[0221] As shown in FIG. 24, the resonance part (resonant photonic crystal waveguide) 48 of the waveguide element 47 has a ring shape. The resonating part 48 has a multilayer structure in which the Y-axis direction, which is a direction perpendicular to the main surface of the substrate 2, is stacked, specifically, a structure in which a plurality of ring-shaped layers are stacked in the Y-axis direction. The center axis direction of the ring is the refractive index periodic direction. Further, the resonance part 48 satisfies the above formula (3). For this reason, leakage of propagating light on the Brillouin zone boundary in a direction along a plane perpendicular to the Y-axis direction that is the refractive index periodic direction does not occur. In Embodiment 15, since the air around each waveguide is air, the refractive index n is 1.

S

is there. The resonator 48 has a configuration in which clads are arranged on the upper and lower surfaces of the core. Both the clad and the core are used as a one-dimensional photonic crystal, and propagation light leaks on the Brillouin zone boundary in the stacking direction. Not to be. Thereby, in the resonance part 48, the propagation light on the side surface and upper / lower surface force Brillouin zone boundary does not leak.

[0222] The resonating part 48, which is a ring-shaped one-dimensional photonic crystal having such a configuration, functions as a resonator by coupling an evanescent wave from its side surface. In other words, the predetermined frequency Only a certain number of lights are coupled to the resonance part 48 and resonate inside the resonance part 48. Therefore, in the waveguide element 47, the distance between the incident-side waveguide 43 and the resonance part 48 and the distance between the resonance part 48 and the emission-side waveguide 44 are set to appropriate distances. Can be used as a resonant element.

[0223] Next, the operation of the waveguide element 47 of the fifteenth embodiment will be described.

[0224] First, the resonating unit 48 is designed so that, for example, only light of wavelength λ resonates. Illustration

1

For example, the resonance part 48 having a desired resonance frequency is manufactured by changing the size, shape, and the like.

[0225] Then, the incident-side waveguide 43 includes a plurality of incident light beams having wavelengths λ.

1

Propagate 76. In this case, the incident light 76 is propagated so as to be in a propagation mode on the Brillouin zone boundary. As a result, only light of a wavelength resonates within the resonating section 48 and is emitted.

1

The light is coupled to the side waveguide 44 and emitted from the emission side waveguide 44 as selection light 77. The outgoing light 78 other than the selection light 77 is emitted from the outgoing side end face of the incident side waveguide 43. In other words, in the waveguide element 47, only light of a wavelength is transmitted from the incident side waveguide 43 to the output side waveguide 4.

1

Light other than that transmitted through 4 is emitted from the incident-side waveguide 43 without being coupled by the resonator 48.

[0226] When the ring-shaped resonating portion 48 is used as described above, the resonance length can be increased.

As a result, the free spectral region (FSR) is narrowed, so that a plurality of frequencies at regular intervals can be resonated. Further, by using a time delay required for propagation, the waveguide element 47 can also function as an optical buffer memory or a multiple pulse generation element.

[0227] Although the resonance element has been described above, the shape of the resonance portion (resonator) of the resonance element is not limited to a cylindrical shape or a ring shape, but may be a rectangular parallelepiped shape, for example. The shape of the resonance part (resonator) of the resonance element can be freely designed according to the resonance frequency.

[Embodiment 16]

A waveguide element according to the sixteenth embodiment of the present invention will be described with reference to the drawings. The waveguide device of the sixteenth embodiment is a multimode force bra. FIG. 25 is a perspective view showing the configuration of the waveguide element according to the sixteenth embodiment of the present invention. As shown in FIG. 25, the waveguide element 51 of the sixteenth embodiment includes a substrate 2 and a branching waveguide (resonant photonic crystal waveguide) 52 provided on the substrate 2. . The branching waveguide 52 is the one-dimensional photonic crystal waveguide described above. As described above, the one-dimensional photonic crystal waveguide can propagate a specific higher-order mode light, and can further confine the propagation light.

[0230] The branching waveguide 52 is a multilayer structure in which the Y-axis direction that is perpendicular to the main surface of the substrate 2 is the stacking direction, and has a refractive index periodicity in the stacking direction.

[0231] The branching waveguide 52 is composed of an incident-side waveguide (incident-side photonic crystal waveguide) 53 and a slab waveguide (slab slab width) wider than the incident-side waveguide 53 (length in the X-axis direction). And a plurality of output side waveguides (output side photonic crystal waveguides) 55. The slab waveguide 54 is connected to the entrance-side waveguide 53 and the exit-side waveguide 55, respectively. In the slab waveguide 54, the exit-side guide is formed on the surface opposite to the surface to which the entrance-side waveguide 53 is connected. Waveguide 55 is connected.

The branching waveguide 52 is the photonic crystal waveguide 140 shown in FIGS. 7A and 7B, and also satisfies the above equation (3). For this reason, the leakage of propagating light on the Brillouin zone boundary in the direction along the plane perpendicular to the Y-axis direction which is the refractive index periodic direction does not occur. In Embodiment 16, since the air around each waveguide is air, the refractive index n is 1.

S

The In addition, as described above, both the cladding and the core are made to be one-dimensional photonic crystals so that the propagation light does not leak on the Brillouin zone boundary in the stacking direction. As a result, in the branching waveguide 52, the propagation light on the Brillouin zone boundary does not leak from the side surface and the upper and lower surfaces.

[0233] Next, the operation of the waveguide element 51 of the sixteenth embodiment will be described.

The incident light 75 is propagated through the incident side waveguide 53. In this case, the incident light 75 is propagated so as to be in a propagation mode on the Brillouin zone boundary. Incident light 75 that has entered the slab waveguide 54 from the incident-side waveguide 53 propagates through the slab waveguide 54 and is branched into four by the action of the multimode cover, and each of the four incident-side waveguides 55 The light is emitted as outgoing light 78.

[Embodiment 17] A waveguide element according to the seventeenth embodiment of the present invention will be described with reference to the drawings. The waveguide element according to the seventeenth embodiment is a wavelength separation element. FIG. 26 is a perspective view showing the configuration of the waveguide element according to the seventeenth embodiment of the present invention.

As shown in FIG. 26, a waveguide element 56 according to the seventeenth embodiment includes a substrate 2 and a wavelength separation waveguide (resonant photonic crystal waveguide) 57 provided on the substrate 2. The The wavelength separation waveguide 57 is the one-dimensional photonic crystal waveguide described above. As described above, the one-dimensional photonic crystal waveguide can propagate a specific higher-order mode light, and can further confine the propagation light.

[0237] The wavelength separation waveguide 57 is a multilayer structure in which the Y-axis direction, which is the direction perpendicular to the main surface of the substrate 2, is the lamination direction, and has a refractive index periodicity in the lamination direction.

[0238] The wavelength separation waveguide 57 includes an incident-side waveguide (incident-side photonic crystal waveguide) 58 and a slab waveguide (slab length) that is wider than the incident-side waveguide 58 (length in the X-axis direction). And a plurality of output-side waveguides (output-side photonic crystal waveguides) 60. The slab waveguide 59 is connected to the entrance-side waveguide 58 and the exit-side waveguide 60, respectively. In the slab waveguide 59, the exit-side surface faces the surface where the entrance-side waveguide 58 is connected. Waveguide 60 is connected.

The wavelength separation waveguide 57 is the photonic crystal waveguide 140 shown in FIGS. 7A and 7B, and also satisfies the above equation (3). For this reason, leakage of propagating light on the Brillouin zone boundary in a direction along a plane perpendicular to the Y-axis direction that is the refractive index periodic direction does not occur. In Embodiment 17, since the air around each waveguide is air, the refractive index n is 1.

S

is there. In addition, as described above, both the cladding and the core are made of a one-dimensional photonic crystal so that propagating light does not leak on the Brillouin zone boundary in the stacking direction. As a result, in the wavelength separation waveguide 57, the propagating light on the Brillouin zone boundary does not leak from the side surface and the upper and lower surfaces.

[0240] By providing two exit-side waveguides 60 and appropriately designing the dimensions of the slab waveguide 59, it is desired to select a plurality of lights incident from the entrance-side waveguide 58 and having different wavelengths. Only light having a wavelength can be extracted from each of the exit-side waveguides 60 as selection light 77. That is, the waveguide element 56 can function as a wavelength separation element. [0241] Next, the operation of the waveguide element 56 of the seventeenth embodiment will be described.

[0242] The incident light 75 is propagated in the incident-side waveguide 58. In this case, the incident light 75 is propagated so as to be in a propagation mode on the Brillouin zone boundary. The incident light 75 incident on the slab waveguide 59 from the incident-side waveguide 58 is separated for each wavelength by propagating through the slab waveguide 59, and is output as the selection light 77 from the two output-side waveguides 60, respectively. Is done.

[0243] As described above, the waveguide element and the laser generator in the embodiment of the present invention are configured using a one-dimensional photonic crystal waveguide capable of performing complete light confinement. For this reason, there is no restriction on the shape and size with which the degree of freedom of design is high. Even when used as a resonator, the resonance frequency, the number of modes, the resonance direction, and the like can be set to desired values and directions without restrictions. As a result, it is possible to realize a waveguide element and a laser generator that can be integrated and have higher performance. In addition, the one-dimensional photonic crystal waveguide is a multilayer structure having a refractive index periodicity only in one direction, and thus can be easily manufactured. In addition, the one-dimensional photonic crystal waveguide for resonating light and the one-dimensional photonic crystal waveguide for exciting laser light have no restrictions on the shape in the direction that does not have refractive index periodicity. Therefore, the degree of freedom in design is high.

[0244] In any of the waveguide elements or laser generators of Embodiments 1 to 17, it is desirable that the one-dimensional photonic crystal waveguides provided on the substrate 2 have the same configuration. That is, it is desirable that the refractive index period, the wavelength of the propagating light in vacuum, the refractive index of the homogeneous medium in contact with the side surface parallel to the refractive index periodic direction, and the like be the same. Thus, each one-dimensional photonic crystal waveguide can be easily manufactured by forming a multilayer structure on the substrate and performing an etching process or the like.

In Embodiments 1 to 17, the case where the side surface and the top surface of the one-dimensional photonic crystal waveguide provided on the substrate 2 are in contact with air has been described as an example. Instead, quartz resin material or the like may be used.

[0246] Further, in each one-dimensional photonic crystal waveguide, the refractive index period, the wavelength of propagating light in a vacuum, the refractive index of a homogeneous medium in contact with the side surface parallel to the refractive index periodic direction, etc. are not necessarily the same. The waveguide element and laser generator of the above embodiment can be realized. Industrial applicability

The waveguide element and laser generator of the present invention can be used as various optical elements such as a switching element, an optical amplification element, a resonance element, a wavelength separation element, and a demultiplexing element.

Claims

The scope of the claims

[1] A resonant photonic crystal waveguide comprising a photonic crystal having a refractive index periodicity in one direction and having a core that propagates an electromagnetic wave existing on the Brillouin zone boundary in the direction without the refractive index periodicity. A waveguide element comprising a waveguide,

The resonant photonic crystal waveguide is

The refractive index of the homogeneous medium that is in contact with the side of the core parallel to the direction having the refractive index periodicity of the core is n, the refractive index period of the core is a, and the electromagnetic wave propagating in the core

S

When the wavelength in a vacuum is estimated,

0

a / λ <l / (2n)

0 S

A waveguide element characterized by satisfying the following condition.

2. The waveguide element according to claim 1, further comprising a resonance mechanism that causes resonance in the resonant photonic crystal waveguide.

[3] The resonance mechanism is:

The resonant photonic from a direction substantially perpendicular to the optical axis of the resonant photonic crystal waveguide and substantially perpendicular to the direction of the refractive index periodicity of the core of the resonant photonic crystal waveguide. An evanescent wave is coupled to the core of the crystal waveguide, and in the resonant photonic crystal waveguide, substantially perpendicular to the optical axis of the resonant photonic crystal waveguide and of the resonant photonic crystal waveguide The waveguide element according to claim 2, wherein resonance is generated in a direction substantially perpendicular to the direction of the refractive index periodicity of the core.

[4] The resonance mechanism is substantially perpendicular to the optical axis of the resonant photonic crystal waveguide, and with respect to a direction having the refractive index periodicity of the core of the resonant photonic crystal waveguide. Two waveguides having a substantially vertical optical axis, spaced apart from the resonant photonic crystal waveguide, and disposed with the resonant photonic crystal waveguide sandwiched therebetween,

Each of the two waveguides is composed of a photonic crystal having a refractive index periodicity in one direction, and has a core for propagating an electromagnetic wave existing on the Brillouin zone boundary in a direction not having the refractive index periodicity. A photonic crystal waveguide,

The photonic crystal waveguide is The refractive index of the homogeneous medium in contact with the side of the core of the photonic crystal waveguide parallel to the direction of the refractive index periodicity of the core of the photonic crystal waveguide is n, and the photonic crystal waveguide The refractive index period of the core of a, the photonic crystal

S1 1

When the wavelength in the vacuum of the electromagnetic wave propagating in the core of the waveguide is 01, a / λ <1 / (2η)

1 01 SI

The waveguide device according to claim 3, wherein the condition is satisfied.

5. The waveguide element according to claim 2, wherein the resonance mechanism couples an evanescent wave to the core of the resonance photonic crystal waveguide, which has the same directional force as the optical axis of the resonance photonic crystal waveguide.

[6] The resonance mechanism has the same optical axis as the optical axis of the resonant photonic crystal waveguide, and is spaced apart from the resonant photonic crystal waveguide to sandwich the resonant photonic crystal waveguide. With two waveguides arranged in

The photonic crystal waveguide is

The refractive index of the homogeneous medium in contact with the side of the core of the photonic crystal waveguide parallel to the direction of the refractive index periodicity of the core of the photonic crystal waveguide is

S1, the refractive index period of the core of the phonic crystal waveguide is a

1. When the wavelength in the vacuum of the electromagnetic wave propagating in the core of the photonic crystal waveguide is set to 01, a / λ <1 / (2η)

1 01 SI

The waveguide device according to claim 5, wherein the following condition is satisfied.

[7] The resonant photonic crystal waveguide sandwiches the core from the direction having the refractive index periodicity of the core, and has a refractive index periodicity in the same direction as the direction of the core having the refractive index periodicity. Further comprising a clad having

The resonance mechanism is

A light wave is coupled to the core of the resonant photonic crystal waveguide from the direction having the refractive index periodicity of the core of the resonant photonic crystal waveguide, and the resonant photonic 3. The waveguide element according to claim 2, wherein resonance is generated in a direction having the refractive index periodicity of the core of the resonant photonic crystal waveguide in a crystal crystal waveguide.

[8] The resonance mechanism has an optical axis along a direction having the refractive index periodicity of the core of the resonant photonic crystal waveguide, and is disposed apart from the resonant photonic crystal waveguide. 8. The waveguide element according to claim 7, further comprising a light incident portion.

9. The waveguide element according to claim 8, wherein the light incident portion includes an optical waveguide and a lens that collects light from the optical waveguide.

[10] The light incident section includes a plurality of light sources arranged side by side along a plane perpendicular to the direction of the refractive index periodicity of the core of the resonant photonic crystal waveguide. 9. The waveguide element according to claim 8, wherein the plurality of light sources emit light independently of each other.

[11] The resonant photonic crystal waveguide has a slab-like portion extending along a plane perpendicular to the direction of the refractive index periodicity of the core of the resonant photonic crystal waveguide. Item 11. The waveguide device according to Item 10.

12. The core of the resonant photonic crystal waveguide has a non-linear action.

The waveguide element according to any one of 11 to 11.

13. The core of the resonant photonic crystal waveguide has an amplifying function.

11. A waveguide element according to any one of the above.

14. The waveguide element according to claim 1, wherein the resonant photonic crystal waveguide has a ring shape.

[15] An incident-side photonic crystal waveguide and an exit-side photonic crystal waveguide, and the resonant photonic crystal out of a plurality of electromagnetic waves having different wavelengths propagating in the incident-side photonic crystal waveguide The electromagnetic wave having the resonance frequency of the waveguide resonates in the resonant photonic crystal waveguide and propagates to the outgoing photonic crystal waveguide, and the resonant photonic crystal waveguide and the resonant A photonic crystal waveguide and the exit side photonic crystal waveguide are disposed;

The entrance-side photonic crystal waveguide and the exit-side photonic crystal waveguide are each composed of a photonic crystal having a refractive index periodicity in one direction, and do not have the refractive index periodicity. Propagating electromagnetic waves present on the Brillouin zone boundary in the direction A photonic crystal waveguide having a core;

The photonic crystal waveguide is

The refractive index of the homogeneous medium in contact with the side of the core of the photonic crystal waveguide parallel to the direction of the refractive index periodicity of the core of the photonic crystal waveguide is n, and the photonic crystal waveguide The refractive index period of the core of a, the photonic crystal

S1 1

1 01 SI

The waveguide element according to claim 1 or 14, wherein the condition of the above condition is satisfied.

[16] It further comprises an incident side photonic crystal waveguide and an exit side photonic crystal waveguide, and has a plurality of the resonant photonic crystal waveguides,

Among a plurality of electromagnetic waves having different wavelengths propagating in the incident-side photonic crystal waveguide, electromagnetic waves having a resonance frequency of the resonant photonic crystal waveguide are sequentially transmitted through the plurality of resonant photonic crystal waveguides. The incident-side photonic crystal waveguide, the plurality of resonant photonic crystal waveguides, and the output-side photonic crystal waveguide so as to resonate and propagate to the output-side photonic crystal waveguide. And are arranged,

The entrance-side photonic crystal waveguide and the exit-side photonic crystal waveguide are each composed of a photonic crystal having a refractive index periodicity in one direction, and do not have the refractive index periodicity. A photonic crystal waveguide with a core that propagates electromagnetic waves that exist on the Brillouin zone boundary in the direction,

The photonic crystal waveguide is

S1 1

1 01 SI

[17] An incident side photonic crystal waveguide and a plurality of output side photonic crystal waveguides are further provided, Having the same number of the resonant photonic crystal waveguides as the plurality of exit side photonic crystal waveguides;

Resonant frequencies of the plurality of resonant photonic crystal waveguides are different from each other, and a plurality of electromagnetic waves having different wavelengths propagating in the incident side photonic crystal waveguide Each of the electromagnetic waves having a resonance frequency resonates in the corresponding resonant photonic crystal waveguide and propagates to the corresponding outgoing photonic crystal waveguide. A waveguide, the plurality of resonant photonic crystal waveguides, and the plurality of emission-side photonic crystal waveguides,

Each of the incident side photonic crystal waveguide and the plurality of output side photonic crystal waveguides is composed of a photonic crystal having a refractive index periodicity in one direction, and has no refractive index periodicity! /, A photonic crystal waveguide with a core that propagates electromagnetic waves present on the Brillouin zone boundary in the direction,

The photonic crystal waveguide is

The refractive index of the homogeneous medium in contact with the side surface of the core of the photonic crystal waveguide parallel to the direction of the refractive index periodicity of the core of the photonic crystal waveguide is n.

S1, the refractive index period of the core of the photonic crystal waveguide is a

1 01 SI

A waveguide device comprising a slab-like photonic crystal waveguide, an incident side photonic crystal waveguide, and a plurality of output side photonic crystal waveguides,

The slab-like photonic crystal waveguide extends in a direction parallel to a plane perpendicular to a direction having a refractive index periodicity,

The incident-side photonic crystal waveguide is connected to the slab photonic crystal waveguide,

The plurality of output-side photonic crystal waveguides are in contact with a surface of the slab-like photonic crystal waveguide that faces the surface to which the incident-side photonic crystal waveguide is connected. Continued,

The slab-like photonic crystal waveguide, the incident-side photonic crystal waveguide, and the plurality of exit-side photonic crystal waveguides are each composed of a photonic crystal having a refractive index periodicity in one direction, A homogeneous medium having a core for propagating electromagnetic waves existing on a Brillouin zone boundary in a direction not having the refractive index periodicity and in contact with a side surface of the core parallel to the direction having the refractive index periodicity Refractive index n, bending of the core

S

When the refractive index period is a and the wavelength of the electromagnetic wave propagating in the core is in vacuum

0 to

a / λ <l / (2n)

0 S

A waveguide element characterized by satisfying the following condition.

[19] The slab-like photonic crystal waveguide branches light incident from the incident-side photonic crystal waveguide and makes it incident on each of the plurality of outgoing-side photonic crystal waveguides. 18. A waveguide element according to 18.

[20] The slab-like photonic crystal waveguide separates a plurality of lights incident from the incident-side photonic crystal waveguide for each wavelength, and the plurality of the emission-side photonic crystal waveguides 19. The waveguide element according to claim 18, which is incident on each of the waveguide elements.

[21] A pumped photonic crystal waveguide composed of a photonic crystal having a refractive index periodicity in one direction and having a core that propagates electromagnetic waves existing on the Brillouin zone boundary in the direction without the refractive index periodicity. A waveguide,

A laser generator including an excitation mechanism for exciting the excitation photonic crystal waveguide to oscillate laser light,

The excitation photonic crystal waveguide is

S

When the wavelength in a vacuum is estimated,

0

a / λ <l / (2n)

0 S

Meet the requirements of

The laser generator characterized in that the core has a light emitting action. [22] The emission photonic crystal waveguide further comprising an optical axis substantially perpendicular to the direction of the refractive index periodicity of the core of the excitation photonic crystal waveguide,

The exit-side photonic crystal waveguide is composed of a photonic crystal having a refractive index periodicity in one direction, and has a core for propagating an electromagnetic wave existing on a Brillouin zone boundary in a direction not having the refractive index periodicity. A photonic crystal waveguide, the photonic crystal waveguide is

S1 1

1 01 SI

Meet the requirements of

The excitation mechanism includes two electrodes disposed across the excitation photonic crystal waveguide from a direction having the refractive index periodicity of the core of the excitation photonic crystal waveguide, and a voltage between the two electrodes. And applying a voltage between the two electrodes to excite the excitation photonic crystal waveguide to oscillate the laser beam,

The laser generator according to claim 21, wherein the oscillated laser beam is incident on the emission-side photonic crystal waveguide.

[23] The excitation mechanism is configured by irradiating the excitation photonic crystal waveguide with excitation light.

The laser beam is oscillated by exciting the excitation photonic crystal waveguide.

The laser generator according to 1.

[24] The output side having an optical axis that is substantially perpendicular to the direction of irradiating the excitation light and substantially perpendicular to the direction of the refractive index periodicity of the core of the excitation photonic crystal waveguide Further comprising a photonic crystal waveguide,

51 1

1 01 SI

Meet the requirements of

The excitation mechanism irradiates the excitation photonic crystal waveguide with the excitation light from a direction substantially perpendicular to a direction having the refractive index periodicity of the core of the excitation photonic crystal waveguide. Exciting the excitation photonic crystal waveguide to oscillate the laser light,

24. The laser generator according to claim 23, wherein the oscillated laser beam is incident on the emission-side photonic crystal waveguide.

[25] The excitation mechanism is substantially perpendicular to the optical axis of the emission-side photonic crystal waveguide and has a direction of the refractive index periodicity of the core of the excitation photonic crystal waveguide. Having two optical waveguides that are spaced apart from the excitation photonic crystal waveguide and sandwiched between the excitation photonic crystal waveguide,

The photonic crystal waveguide is

52 2

When the wavelength in the vacuum of the electromagnetic wave propagating in the core of the waveguide is 02, a / λ <1 / (2η)

2 02 S2

25. The laser generator according to claim 24, which satisfies the following condition.

[26] In the direction having the refractive index periodicity of the core of the excitation photonic crystal waveguide An exit-side photonic crystal waveguide having an optical axis substantially perpendicular to the optical axis; and the exit-side photonic crystal waveguide is composed of a photonic crystal having a refractive index periodicity in one direction, and the refractive index period A photonic crystal waveguide having a core for propagating an electromagnetic wave existing on a Brillouin zone boundary in a direction not having the property, the photonic crystal waveguide is

S1 1

1 01 SI

Meet the requirements of

The excitation photonic crystal waveguide sandwiches the core of the excitation photonic crystal waveguide from the direction having the refractive index periodicity of the core of the excitation photonic crystal waveguide, and the excitation photonic crystal waveguide A clad having a refractive index periodicity in the same direction as the direction having the refractive index periodicity of the core;

The excitation mechanism irradiates the excitation photonic crystal waveguide by irradiating the excitation photonic crystal waveguide with the excitation light from a direction having the refractive index periodicity of the core of the excitation photonic crystal waveguide. 24. The laser generator according to claim 23, wherein the laser beam is excited to oscillate, and the oscillated laser beam is incident on the emission-side photonic crystal waveguide.

[27] The excitation mechanism has an optical axis along a direction having the refractive index periodicity of the core of the excitation photonic crystal waveguide, and is disposed apart from the excitation photonic crystal waveguide. 27. The laser generator according to claim 26, further comprising a light incident portion.

28. The laser generator according to claim 27, wherein the light incident part includes an optical waveguide and a lens that collects light from the optical waveguide.

[29] The excitation mechanism irradiates the excitation photonic crystal waveguide with the excitation light from a direction substantially perpendicular to a direction having the refractive index periodicity of the core of the excitation photonic crystal waveguide. The excitation photonic crystal waveguide is excited by Oscillate the light,

24. The laser generator according to claim 23, wherein the oscillated laser beam is emitted from the excitation photonic crystal waveguide in a direction having the refractive index periodicity of the core of the excitation photonic crystal waveguide.

[30] The excitation mechanism has an optical axis substantially perpendicular to the direction of the refractive index periodicity of the core of the excitation photonic crystal waveguide, and is separated from the excitation photonic crystal waveguide. Each of the two waveguides is composed of a photonic crystal having a refractive index periodicity in one direction, and the refractive index period A photonic crystal waveguide having a core that propagates electromagnetic waves that exist on the Brillouin zone boundary in a direction that does not have the property,

The photonic crystal waveguide is

1 01 SI

30. The laser generator according to claim 29, which satisfies the following condition.

[31] The laser generation according to any one of claims 24 to 28, wherein a reflection layer of a distribution feedback resonator is disposed between the excitation photonic crystal waveguide and the emission side photonic crystal waveguide. vessel.