JP2006337574A - Waveguide element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a waveguide element that can be manufactured easily because of simple structure, that can be miniaturized, and that is suitable for vertical coupling. <P>SOLUTION: The waveguide element is a laminate, having refractive index periodicity in one direction and has: a photonic crystal 2, which is a core having a bottom face vertical to the refractive index periodic direction, an incident slope 2a and an exiting slope 2b both tilted with respect to the bottom face, an incident section 3, and an outgoing section 4. Light is made incident to the bottom face of the photonic crystal 2 by the incident section 3, and the light 5, made incident on the photonic crystal 2, is reflected by the incident slope 2a, producing in the photonic crystal 2 propagation light 8 by a band on the Billouin zone boundary. The propagation light 8 is reflected by the exiting slope 2b, with a light 6 emitted from the bottom face of the photonic crystal 2 and guided to the outgoing section 4. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a waveguide element using a one-dimensional photonic crystal as a core.

  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 has attracted attention, and research and development have been actively conducted. The structure of this defect waveguide will be described. First, a two-dimensional photonic crystal having a two-dimensional refractive index periodic structure is formed by forming regular holes in a thin film layer using, for example, Si having a high refractive index. This two-dimensional photonic crystal has a photonic band gap in the operating frequency range in all directions within a plane extending in the direction having the refractive index period. Further, a defect waveguide is formed by providing a linear defect in the two-dimensional photonic crystal. The light can propagate through the defect portion of the defect waveguide, and cannot propagate through the portion where no defect is provided. Therefore, the light is confined in the defect portion and can propagate without leaking. Thereby, steep bending of light is possible. Therefore, by using this defect waveguide as a wiring, the degree of freedom in designing an optical circuit is increased, and miniaturization or integration is possible. Further, by using this defect waveguide as a part of the optical element, the optical element can be reduced in size.

  Further, it is possible to cause a group velocity abnormality in the light propagating in the defect waveguide. Therefore, a large non-linear action can be obtained, and when used as a part of the optical element, improvement of the characteristics and miniaturization of the optical element can be realized. In addition, the waveguide element using a two-dimensional photonic crystal is disclosed by patent document 1, patent document 2, patent document 3, patent document 4, and patent document 5, for example. In practice, it is common to use a waveguide in which the above-described defect waveguide is combined with a simple silicon wire with little propagation loss.

  In addition, a one-dimensional photonic crystal that can be easily manufactured because it has a simpler structure than a two-dimensional photonic crystal can also be used as a waveguide element (see, for example, Patent Document 6).

  It has been proposed to use an optical circuit including such a waveguide element in combination with an electronic circuit. Specifically, an electronic circuit including a light emitting unit and a light receiving unit may be combined with an optical circuit. The optical signal output from the light emitting unit may be received by the optical circuit, and the optical signal output from the optical circuit may be received by the light receiving unit. In this way, by combining the optical circuit and the electronic circuit, a circuit having both high-speed processing by the optical circuit and flexible processing by the electronic circuit is configured. When coupling an optical circuit and an electronic circuit, there are generally two types of coupling: end face coupling and vertical coupling. FIG. 17 is a perspective view showing a configuration in which an optical circuit and an electronic circuit are combined. FIG. 17A shows end face coupling, and FIG. 17B shows vertical coupling. As shown in FIG. 17 (a), the end surface coupling of the planar electronic circuit 100 and the optical circuit 200 facing each other, and the planar electronic circuit as shown in FIG. 17 (b). There is a vertical coupling in which 100 and the optical circuit 200 are arranged one above the other and their upper and lower surfaces face each other. The electronic circuit 100 includes a light emitting unit that outputs an optical signal, a light receiving unit that receives the optical signal, and the like, and a conductive wire 101. The optical circuit 200 includes an output unit that outputs an optical signal, an input unit that receives the optical signal, and the like.

  In the end face coupling shown in FIG. 17A, the light emitting section and the light receiving section must be installed on the end face 102 of the electronic circuit 100. Similarly, an output unit and an input unit must be installed on the end surface 201 of the optical circuit 200. Since the electronic circuit 100 and the optical circuit 200 that input and output the optical signal 300 are planar, their end surfaces 102 and 201 have smaller areas than the other surfaces. For this reason, the light emitting unit, the light receiving unit, the output unit, and the input unit are arranged in a line, and the number that can be installed is small.

  However, in the vertical coupling shown in FIG. 17B, the light emitting unit, the light receiving unit, the output unit, and the input unit are installed on the main surfaces (upper and lower surfaces) 103 and 202 of the electronic circuit 100 and the optical circuit 200, respectively. Since the main surfaces 103 and 202 have a larger area than the end surfaces 102 and 201, the number of light emitting units, light receiving units, output units, and input units can be increased. That is, the degree of freedom in circuit design increases. Therefore, when the electronic circuit 100 and the optical circuit 200 are fused, it is preferable to use vertical coupling.

In the case of a planar optical circuit, the emitted light usually travels in a direction parallel to the main surface of the optical circuit and is emitted from the end face. Therefore, when using vertical coupling, it is necessary to bend the emitted light at a right angle. For example, the wavelength demultiplexing element disclosed in Patent Document 5 can resonate a specific frequency component and extract an optical signal having the frequency component in the vertical direction. For example, since the optical element disclosed in Patent Document 6 includes a prism and a diffraction grating, the optical path can be bent. By using such optical elements, vertical coupling can be easily realized.
JP 2004-212416 A JP 2004-170478 A JP 2004-296560 A JP 2004-093787 A JP 2004-119671 A International Publication No. 05/008305 Pamphlet

  Here, in the case of the silicon fine wire waveguide or the above-described two-dimensional photonic crystal defect waveguide, the core diameter is usually 0.5 μm or less and very small. Therefore, it is difficult to align the optical axis for coupling with external light such as an optical fiber, and the coupling loss increases.

  If these waveguides are installed on a planar optical circuit, the emitted light is emitted in a direction suitable for end face coupling (see FIG. 17A). In order to make the direction suitable for the vertical coupling (see FIG. 17B), it is necessary to add a manufacturing process such as obliquely processing the exit end face of the defect waveguide at 45 °.

  Further, the above-described wavelength separation element that resonates specific frequency components and extracts them in the vertical direction cannot simultaneously extract optical signals including a plurality of frequency components.

  In addition, a waveguide element using a one-dimensional photonic crystal can be easily coupled to an optical fiber because the core diameter of the one-dimensional photonic crystal waveguide is about several μm. However, the conventional one-dimensional photonic crystal waveguide requires a prism and a diffraction grating in order to achieve vertical coupling. However, since the size of the waveguide element is about 10 μm, it is difficult to actually manufacture a prism and a diffraction grating corresponding to the waveguide element.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a waveguide element suitable for vertical coupling that can be easily manufactured because of its simple structure and can be miniaturized. And

  The first waveguide element of the present invention is a laminate having a refractive index periodicity in one direction, a bottom surface perpendicular to the refractive index periodic direction, and an incident side inclined with respect to the bottom surface A waveguide device comprising a core photonic crystal having an inclined surface and an exit-side inclined surface, an incident portion, and an exit portion, wherein the incident portion emits light to the bottom surface of the photonic crystal. The light incident on the photonic crystal is reflected by the incident side inclined surface, and propagated light is generated in the photonic crystal by a band on the Brillouin zone boundary. Light reflected from the inclined surface is emitted from the bottom surface of the photonic crystal, and the light emitted from the photonic crystal is guided to the emitting portion.

  The second waveguide element of the present invention is a laminate having a refractive index periodicity in one direction, and is inclined with respect to the bottom surface perpendicular to the refractive index periodic direction and the bottom surface. A waveguide device having a photonic crystal that is a core having an inclined surface and an incident part, wherein the incident part causes light to enter the bottom surface of the photonic crystal, and The incident light is reflected by the inclined surface, and propagating light is generated in the photonic crystal by a band on the Brillouin zone boundary.

  The third waveguide element of the present invention is a laminate having a refractive index periodicity in one direction, and is inclined with respect to the bottom surface perpendicular to the refractive index periodic direction and the bottom surface. A waveguide device having a photonic crystal that is a core having an inclined surface and an emission part, and light propagated by a band on a Brillouin zone boundary propagating in the photonic crystal is reflected by the inclined surface Then, light is emitted from the bottom surface of the photonic crystal, and the light emitted from the photonic crystal is guided to the emission portion.

  The fourth waveguide element of the present invention is a laminate having a refractive index periodicity in one direction, a bottom surface perpendicular to the refractive index periodic direction, a top surface facing the bottom surface, A waveguide device having a photonic crystal as a core, an incident portion, and an exit portion, each having an entrance-side diffraction grating and an exit-side diffraction grating formed on an upper surface, wherein the entrance portion is the photonic crystal Light is incident on the bottom surface of the crystal, the light incident in the photonic crystal is reflected by the incident-side diffraction grating, and a propagating light is generated in the photonic crystal by a band on the Brillouin zone boundary, The propagating light is reflected by the emission side diffraction grating, light is emitted from the bottom surface of the photonic crystal, and light emitted from the photonic crystal is guided to the emission part.

  The fifth waveguide element of the present invention is a laminate having a refractive index periodicity in one direction, a bottom surface perpendicular to the refractive index periodic direction, a top surface facing the bottom surface, A waveguide element having a photonic crystal as a core having a diffraction grating formed on an upper surface and an incident part, wherein the incident part causes light to be incident on the bottom surface of the photonic crystal, and Light incident on the photonic crystal is reflected by the diffraction grating, and propagation light is generated in the photonic crystal due to a band on the Brillouin zone boundary.

  Further, a sixth waveguide element of the present invention is a laminate having a refractive index periodicity in one direction, a bottom surface perpendicular to the refractive index periodic direction, a top surface facing the bottom surface, A waveguide device having a photonic crystal that is a core having a diffraction grating formed on an upper surface and an emitting portion, and propagating light by a band on a Brillouin zone boundary that propagates in the photonic crystal Light reflected from the diffraction grating is emitted from the bottom surface of the photonic crystal, and the light emitted from the photonic crystal is guided to the emission portion.

  According to the present invention, it is possible to provide a waveguide element suitable for vertical coupling that can be easily manufactured because of its simple configuration and can be miniaturized.

  The first waveguide element of the present invention includes a photonic crystal that is a core. This photonic crystal has an incident side inclined surface and an emission side inclined surface, and light is incident and emitted from the bottom surface of the photonic crystal. The incident light is reflected by the incident side inclined surface, so that propagating light is generated in the photonic crystal by a band on the Brillouin zone boundary. Moreover, light is emitted from the photonic crystal by reflecting the propagating light on the outgoing inclined surface. Thus, in this waveguide element, the traveling directions of the incident light and the emitted light are different from those of the propagating light. Therefore, this waveguide element is suitable for vertical coupling. Further, since propagation on the Brillouin zone boundary is used, it can also be used as a light control element. In addition, since a one-dimensional photonic crystal is used, the structure is simple, so that it can be easily manufactured and the size can be reduced.

  In the first waveguide element of the present invention, preferably, a reflection layer is formed on each of the incident side inclined surface and the emission side inclined surface. Thereby, in the waveguide element, loss of light can be reduced and high coupling efficiency can be realized.

  The second waveguide element of the present invention includes a photonic crystal that is a core. This photonic crystal has an inclined surface, and light enters from the bottom surface of the photonic crystal. The incident light is reflected by the inclined surface, so that propagating light is generated in the photonic crystal due to the band on the Brillouin zone boundary. Thus, this waveguide element has different traveling directions of incident light and propagating light. Therefore, this waveguide element is suitable for vertical coupling. Further, since propagation on the Brillouin zone boundary is used, it can also be used as a light control element. In addition, since a one-dimensional photonic crystal is used, the structure is simple, so that it can be easily manufactured and the size can be reduced.

  The third waveguide element of the present invention includes a photonic crystal that is a core. This photonic crystal has an inclined surface, and light is emitted from the bottom surface of the photonic crystal. Light propagated by the band on the Brillouin zone boundary is reflected by the inclined surface, so that light is emitted from the photonic crystal. As described above, in this waveguide element, the traveling directions of the emitted light and the propagating light are different. Therefore, this waveguide element is suitable for vertical coupling. Further, since propagation on the Brillouin zone boundary is used, it can also be used as a light control element. In addition, since a one-dimensional photonic crystal is used, the structure is simple, so that it can be easily manufactured and the size can be reduced.

  In the second or third waveguide element of the present invention, preferably, a reflective layer is formed on the inclined surface. Thereby, in the waveguide element, loss of light can be reduced and high coupling efficiency can be realized.

  In the first to third waveguide elements of the present invention, preferably, the reflective layer is a metal film. Thereby, a reflective layer with a high reflectance can be formed easily.

  In the first to third waveguide elements of the present invention, preferably, the reflective layer is a dielectric multilayer film. Thereby, a reflective layer can be formed easily.

  The fourth waveguide element of the present invention includes a photonic crystal that is a core. This photonic crystal has an incident side diffraction grating and an output side diffraction grating, and light is incident and emitted from the bottom surface of the photonic crystal. The incident light is reflected by the incident side diffraction grating, so that propagating light is generated in the photonic crystal due to the band on the Brillouin zone boundary. Moreover, light is emitted from the photonic crystal because the propagating light is reflected by the exit side diffraction grating. Thus, in this waveguide element, the traveling directions of the incident light and the emitted light are different from those of the propagating light. Therefore, this waveguide element is suitable for vertical coupling. Further, since propagation on the Brillouin zone boundary is used, it can also be used as a light control element. In addition, since a one-dimensional photonic crystal is used, the structure is simple, so that it can be easily manufactured and the size can be reduced.

  The fifth waveguide element of the present invention includes a photonic crystal that is a core. This photonic crystal has a diffraction grating, and light enters from the bottom of the photonic crystal. The incident light is reflected by the diffraction grating, so that propagating light is generated in the photonic crystal due to the band on the Brillouin zone boundary. Thus, this waveguide element has different traveling directions of incident light and propagating light. Therefore, this waveguide element is suitable for vertical coupling. Further, since propagation on the Brillouin zone boundary is used, it can also be used as a light control element. In addition, since a one-dimensional photonic crystal is used, the structure is simple, so that it can be easily manufactured and the size can be reduced.

  The sixth waveguide element of the present invention includes a photonic crystal that is a core. This photonic crystal has a diffraction grating, and light is emitted from the bottom surface of the photonic crystal. Light propagated by the band on the Brillouin zone boundary is reflected by the diffraction grating, and light is emitted from the photonic crystal. As described above, in this waveguide element, the traveling directions of the emitted light and the propagating light are different. Therefore, this waveguide element is suitable for vertical coupling. Further, since propagation on the Brillouin zone boundary is used, it can also be used as a light control element. In addition, since a one-dimensional photonic crystal is used, the structure is simple, so that it can be easily manufactured and the size can be reduced.

  In the first or fourth waveguide element of the present invention, preferably, the traveling direction of light incident on the photonic crystal or the traveling direction of light emitted from the photonic crystal is This is the same direction as the refractive index periodic direction of the photonic crystal. Thereby, an optical circuit on which this waveguide element is mounted can be vertically coupled.

  In the second or fifth waveguide element of the present invention, preferably, the traveling direction of light incident on the photonic crystal is the same direction as the refractive index periodic direction of the photonic crystal. . Thereby, an optical circuit on which this waveguide element is mounted can be vertically coupled.

  In the third or sixth waveguide element of the present invention, preferably, the traveling direction of light emitted from the photonic crystal is the same direction as the refractive index periodic direction of the photonic crystal. . Thereby, an optical circuit on which this waveguide element is mounted can be vertically coupled.

(Embodiment 1)
A waveguide element according to Embodiment 1 of the present invention will be described with reference to the drawings. FIG. 1 is a perspective view showing the configuration of a waveguide element according to Embodiment 1 of the present invention. FIG. 2 is a side view showing the configuration of the waveguide element according to Embodiment 1 of the present invention. 1 and 2, the refractive index periodic direction of the photonic crystal waveguide is the Y-axis direction, the light propagation direction is the Z-axis direction, and the Y-axis direction and the direction perpendicular to the Z-axis direction are the X-axis direction. And

  As shown in FIG. 1, the waveguide element 10 according to the first embodiment includes a substrate 1, a one-dimensional photonic crystal 2, an incident part 3, and an emission part 4. The substrate 1 is made of a translucent material.

The photonic crystal 2 is a laminated structure in which two kinds of substances having different refractive indexes are alternately laminated. Since the layer thickness of each of these substances is constant, the photonic crystal 2 has a refractive index periodicity only in one direction. Further, the incident side inclined surface 2a and the emission side inclined surface 2b which are both end faces of the photonic crystal 2 are inclined with respect to the XZ plane perpendicular to the Y-axis direction which is the refractive index periodic direction. For example, the incident side inclined surface 2a and the emission side inclined surface 2b are inclined at an angle ψ _a and an angle ψ _{b with} respect to the bottom surface of the photonic crystal 2 parallel to the XZ plane, respectively. Further, the directions of inclination are opposite to each other. The angle ψ _a and the angle ψ _b may be different values, but the same value is preferable because it is easy to design and manufacture.

  The incident portion 3 includes an optical fiber 3 a, a collimator lens 3 b, and an objective lens 3 c, and is disposed on the bottom surface side of the substrate 1. Further, the incident portion 3 causes incident light 5 to be incident on the bottom surface of the photonic crystal 2 through the substrate 1. Since the incident light 5 travels toward the incident-side inclined surface 2a, the incident portion 3 is arranged to face the incident-side inclined surface 2a.

  The emitting unit 4 includes an optical fiber 4a, a collimator lens 4b, and an objective lens 4c, and is disposed on the bottom surface side of the substrate 1. Further, the light reflected by the outgoing side inclined surface 2 b is emitted from the bottom surface of the photonic crystal 2 as outgoing light 6. Since the outgoing light 6 is guided to the outgoing part 4 through the substrate 1, the outgoing part 4 is arranged to face the outgoing side inclined surface 2b.

  In addition, the structure of the incident part 3 and the output part 4 is not limited to this structure.

  Further, the incident angle and the outgoing angle of the incident light 5 and the outgoing light 6 with respect to the substrate 1 are preferably 0 °. That is, the incident light 5 and the outgoing light 6 are preferably perpendicular to the substrate 1. Thereby, when the waveguide element 10 is used in an optical circuit, vertical coupling can be easily performed. The substrate 1 is parallel to the XZ plane.

  In such a configuration, the photonic crystal 2 is a waveguide core, and the cladding is air surrounding the substrate 1 and the upper and side surfaces of the photonic crystal 2. In addition, it can also be set as a clad by installing a predetermined material around the photonic crystal 2.

  Next, the operation of the waveguide element 10 will be described. First, the incident light 5 propagating through the optical fiber 3a is converted into parallel light by the collimator lens 3b, condensed by the objective lens 3c, and incident on the substrate 1. Light from the incident portion 3 propagates through the substrate 1 and then enters the photonic crystal 2 from the bottom surface of the photonic crystal 2. Incident light 5 propagating through the photonic crystal 2 reaches the incident side inclined surface 2a, is reflected, and propagates in the Z-axis direction. The conditions for reflection in the Z-axis direction can be obtained from the photonic band structure described later.

  The propagating light 8 propagating in the Z-axis direction reaches the exit side inclined surface 2b. The propagating light 8 is reflected by the exit-side inclined surface 2 b and changes its path toward the bottom surface of the photonic crystal 2. The conditions for reflection in the Y-axis direction can be obtained from the photonic band structure described later.

  Further, the light that has been reflected by the outgoing-side inclined surface 2 b and becomes outgoing light 6 is emitted from the bottom surface of the photonic crystal 2. The outgoing light 6 from the photonic crystal 2 is incident on the substrate 1, propagates in the substrate 1, and is emitted from the substrate 1 to the outside. The outgoing light 6 emitted from the substrate 1 is guided to the outgoing part 4. Specifically, the outgoing light 6 emitted from the substrate 1 proceeds in the order of the objective lens 4c and the collimating lens 4b, and enters the optical fiber 4a. The emission unit 4 is installed at a position where light emitted from the substrate 1 is guided.

  Here, it is preferable that the light in the core by the propagating light 8 propagating in the photonic crystal 2 propagates in a mode on the Brillouin zone boundary in the photonic band structure. Thereby, the waveguide element 10 functions as a light control element.

  The propagating light 8 is confined in the XZ plane direction regardless of the propagating direction by satisfying the following formula, by the mode on the Brillouin zone boundary.

a / λ ₀ <1 / (2n _s )

Here, λ ₀ is the wavelength of the propagation light 8 propagating through the photonic crystal 2 in vacuum. a is the refractive index period of the photonic crystal 2 in the Y direction. Further, n _s is the refractive index of the medium in contact with the side surface of the photonic crystal 2, that is, the surface where the periodic structure of the photonic crystal 2 is exposed. In Embodiment 1, it is the refractive index of air as described above. Note that the confinement condition of the propagation light 8 by the mode on the Brillouin zone boundary in the photonic crystal 2 is described in detail in, for example, International Publication No. 05/008305.

The propagation light in the photonic crystal 2 can be known by calculating and illustrating the photonic band. The method of band calculation for photonic bands is described in detail in, for example, “Photonic Crystals, Princeton University Press, (1995)” or “Physical Review B, 1991, 44, 16, p.8565”. . Therefore, the angle ψ _a and the angle ψ _b can be selected by the above band calculation.

  FIG. 3 is a side view for explaining the path of light on the incident side of the waveguide element according to Embodiment 1 of the present invention. FIG. 3 is an enlarged side view showing the vicinity of the incident side inclined surface 2a of the photonic crystal 2, and the incident portion 3 is omitted. In FIG. 3, when incident light 5 is transmitted through the substrate 1 and incident on the photonic crystal 2 from an incident part (not shown), two types of refracted light 7 a and 7 b leak to the outside of the photonic crystal 2. Other than these, the reflected light 8 is reflected by the incident side inclined surface 2a and travels in the Z-axis direction. FIG. 4 is a band diagram corresponding to FIG. FIG. 4 shows the photonic band structure of the photonic crystal 2 that is the core, the substrate 1 that is the incident side medium, and the medium that is in contact with the incident side inclined surface 2a (air in the first embodiment) in the inverse space of the YZ plane. Is shown in FIG. The band diagram of FIG. 4 will be described with reference to FIG.

  The band of the photonic crystal 2 is shown by a periodic zone method in order to show periodicity, and the first band and the second band exist at this frequency. A broken line 11 indicates a boundary between the substrate 1 and the photonic crystal 2, and an inclined broken line 12 indicates a boundary between the incident-side inclined surface 2 a and the air outside the photonic crystal 2.

  Since the substrate 1 and air are homogeneous media, the band indicating them is a simple circle. The center point of each band is a normal line of a broken line 11 and a broken line 12 representing the boundary line between the substrate 1 and the photonic crystal 2 and the boundary line between the air and the photonic crystal 2, and the center point of the photonic crystal 2 Located on a line passing through. Moreover, the arrow shown in FIG. 4 shows the advancing direction of energy in each coupling point AG on a band, and becomes a normal line direction of a band. In FIG. 4, the light at the intersection of the line 13 perpendicular to the broken line 12 representing the boundary between the incident side inclined surface 2 a and the air outside the photonic crystal 2 and intersecting the coupling point A and the incident light 5 Combine with. Here, the propagation mode on the boundary between the incident light 5 incident on the photonic crystal 2 and the Brillouin zone is selected so as to exist on the same normal line across the incident-side inclined surface 2a in FIG. That is, a coupling point A indicating the mode of the incident light 5 and a coupling point B indicating the mode of the propagation light 8 exist on the line 13 orthogonal to the broken line 12.

  Incident light 5 incident from the substrate 1 side is coupled with light from the coupling point A on the second band of the photonic crystal 2. Although there are a plurality of coupling points A, these are all equivalent points based on periodicity. The same applies to the connection points B to G other than the connection point A, and the same connection point represents an equivalent point.

  Light from the coupling point A that is incident on the photonic crystal 2 from the substrate 1 is reflected by the incident side inclined surface 2a and coupled to the coupling point B on the Brillouin zone boundary of the first band. However, there is a possibility of coupling with the light at the coupling point C when reflected by the incident side inclined surface 2a. Further, there is a possibility of coupling with the light at the coupling point D and the coupling point E. However, as is understood from the arrows, the light travels again toward the incident side inclined surface 2a, and thus is reflected light again. Therefore, the light reflected by the incident side inclined surface 2a is only the light at the coupling point B and the coupling point C.

  A line 13 passing through the coupling point A and perpendicular to the broken line 12 intersects with the air band at the coupling point F and the coupling point G, so that the refracted lights 7a and 7b in the directions indicated by the arrows of the respective coupling points are air. Occurs on the side.

  That is, the light shown in FIG. 4 is as follows. The light at the coupling point A is incident light from the substrate 1 to the photonic crystal 2. Light at the coupling point B and the coupling point C is propagating light in the photonic crystal 2. The light at the coupling point F and the coupling point G is refracted light 7a and 7b that leaks to the outside from the incident side inclined surface 2a. Although not shown in FIG. 3, the light at the coupling point C may become reflected return light from the photonic crystal 2 toward the substrate 1.

  Next, the light path in the vicinity of the exit-side inclined surface 2b will be described. FIG. 5 is a side view for explaining the path of light on the emission side of the waveguide element according to Embodiment 1 of the present invention. FIG. 5 is an enlarged side view showing the vicinity of the outgoing side inclined surface 2b of the photonic crystal 2, and the outgoing part 4 is omitted. In FIG. 5, the propagating light 8 in the photonic crystal 2 is reflected by the emission side inclined surface 2b, and the path is changed to the bottom surface side (substrate 1 side) of the photonic crystal 2. Outgoing light 6 emitted from the photonic crystal 2 is emitted through the substrate 1 and guided to an emitting portion (not shown). In addition, the refracted lights 9a and 9b leak to the outside of the photonic crystal 2 on the outgoing side inclined surface 2b. FIG. 6 is a band diagram corresponding to FIG. FIG. 6 shows the photonic band structure of the photonic crystal 2 that is the core, the substrate 1 that is the medium on the output side, and the medium (air in the first embodiment) that is in contact with the inclined surface 2b on the output side. Is shown in FIG. The band diagram of FIG. 6 will be described with reference to FIG.

  The band of the photonic crystal 2 is shown by a periodic zone method in order to show periodicity, and the first band and the second band exist at this frequency. A broken line 16 indicates a boundary between the substrate 1 and the photonic crystal 2, and an inclined broken line 17 indicates a boundary between the emission side inclined surface 2 b and the air outside the photonic crystal 2.

  Since the substrate 1 and air are homogeneous media, the band indicating them is a simple circle. The center point of each band is a normal line of a broken line 16 and a broken line 17 representing a boundary line between the substrate 1 and each of air and the photonic crystal 2, and is located on a line passing through the center point of the photonic crystal 2. Moreover, the arrow shown in FIG. 6 shows the advancing direction of energy at each of the coupling points H to M on the band, which is the normal direction of the band. For example, there are a plurality of coupling points H, but these are all equivalent points based on periodicity. The same applies to the connection points I to M other than the connection point H, and the same connection point represents an equivalent point. In FIG. 6, the light at the intersection of the line 18 orthogonal to the broken line 17 that represents the boundary between the exit-side inclined surface 2 b and the air outside the photonic crystal 2 and intersects the coupling point H and the propagation light 8 It is the light that combines with.

  The light at the coupling point H, which is the propagating light 8 on the Brillouin zone boundary, is coupled with the light at the coupling point I by reflection at the exit-side inclined surface 2b, and becomes the outgoing light 6 perpendicular to the outside as it is. However, there is a possibility that the propagating light 8 is coupled with the light at the coupling point J by reflection at the outgoing side inclined surface 2b. Further, there is a possibility of coupling with the light at the coupling point K. However, as will be understood from the arrow, the light travels again toward the outgoing side inclined surface 2b, and thus is reflected again. Therefore, the light reflected by the incident side inclined surface 2a is only the light at the coupling point I and the coupling point J.

  A line 18 passing through the coupling point H and perpendicular to the broken line 17 intersects the air band at the coupling point L and the coupling point M, so that the refracted lights 9a and 9b in the directions indicated by the arrows at the respective coupling points are air. Occurs on the side.

  The light shown in FIG. 6 will be described below. The light at the coupling point H is propagating light 8 in the photonic crystal 2. The light at the coupling point I is outgoing light that is reflected by the outgoing side inclined surface 2b and travels toward the substrate 1 side. Further, the light at the coupling point L and the coupling point M is refracted light 9a and 9b that leaks to the outside from the exit side inclined surface 2b. Although not shown in FIG. 5, the light at the coupling point J may be emitted from the photonic crystal 2 toward the substrate 1. The light at the coupling point J is in a different direction from the light at the coupling point I.

  4 and 6, the waveguide element 10 of the first embodiment uses light at the coupling point A (incident light 5), light at the coupling point B (propagation light 8), and light at the coupling point H (propagation). Light 8) and light at the coupling point I (emitted light 6).

Further, it is desirable that the light at the coupling point C in FIG. 3 and the light at the coupling point J in FIG. 5 are small. Therefore, for example, the angles ψ _a and ψ _b may be designed in _a frequency region where the diameter of the ellipse indicating the second band of the photonic crystal 2 becomes small. Thereby, it is possible that light at the coupling point J does not exist. As a result, the reflected light at the exit-side inclined surface 2b is combined with the light at the coupling point I, so that the light at the coupling point J does not exist.

  Further, in the waveguide element 10, a reflection layer may be formed on the incident side inclined surface 2a and the emission side inclined surface 2b. FIG. 7 is a side view showing the configuration of the waveguide element including the reflective layer according to Embodiment 1 of the present invention. In FIG. 7, members having the same functions as those shown in FIG. 1 or FIG. 7 is different from FIG. 1 or FIG. 2 in that a reflective layer 21a and a reflective layer 21b are formed on the incident side inclined surface 2a and the output side inclined surface 2b. By forming the reflective layer 21a and the reflective layer 21b in this way, the light at the coupling point F, the coupling point G, the coupling point L, and the coupling point M is converted into a photonic crystal with reference to FIGS. 2, the energy becomes the energy of the propagating light 8 or the outgoing light 6 without leaking to the outside. Thereby, loss can be reduced and coupling efficiency can be increased.

  The reflective layer 21a and the reflective layer 21b may be metal films, for example. In particular, materials such as silver, aluminum, and gold are preferable because of their high reflectance and easy formation. The metal film can be easily formed by, for example, vacuum deposition or sputtering. In addition to the metal film, the reflective layer 21a and the reflective layer 21b may be dielectric multilayer films. Light can be reflected by the dielectric multilayer film. Dielectric multilayer films are generally used as thin film materials and are excellent in terms of durability and film formation cost, such as silica, silicon, titanium oxide, tantalum oxide, niobium oxide, magnesium fluoride, and silicon nitride. A material may be used. Using these materials, a thin film can be easily formed by sputtering, vacuum deposition, ion-assisted deposition, plasma CVD, or the like, and a dielectric multilayer film can be formed.

  In the waveguide element 10 according to the first embodiment described above, the incident light 5 and the outgoing light 6 are substantially perpendicular to the propagating light 8. Therefore, by using the waveguide element 10 according to the first embodiment, an optical circuit suitable for vertical coupling can be formed. In addition, light including a plurality of frequencies can be incident, propagated, and emitted. Further, the waveguide element 10 of the first embodiment can be used as a light control element because it uses propagation on the Brillouin zone boundary. Furthermore, since the waveguide element 10 according to the first embodiment uses a one-dimensional photonic crystal, it can be easily manufactured because of its simple configuration and can be downsized.

(Embodiment 2)
A waveguide element according to Embodiment 2 of the present invention will be described with reference to the drawings. FIG. 8 is a side view showing the configuration of the waveguide element according to Embodiment 2 of the present invention. In FIG. 8, the refractive index periodic direction of the photonic crystal waveguide is the Y-axis direction, the light propagation direction is the Z-axis direction, and the Y-axis direction and the direction perpendicular to the Z-axis direction are the X-axis direction.

  In the waveguide element 10a of the second embodiment, the incident light 5 is incident on the photonic crystal 2 through the substrate 1 and reflected by the incident-side inclined surface 2a, as in the waveguide element 10 of the first embodiment. Propagated light 8 propagates through the photonic crystal 2. However, unlike the first embodiment, the propagation light 8 is emitted without being reflected by the emission-side inclined surface 2b. That is, in the waveguide element 10a of FIG. 8, the incident light 5 is incident on the photonic crystal 2 via the substrate 1, but the emitted light 6a is emitted directly from the emission-side inclined surface 2b. In FIG. 8, members having the same functions as those shown in FIG.

  In the waveguide element 10a, the propagating light 8 is emitted as the outgoing light 6a from the outgoing side inclined surface 2b. Therefore, the emission part 14 to which the emitted light 6 is guided is installed facing the emission side inclined surface 2b.

  Such an operation of the waveguide element 10a will be described. First, the incident light 5 propagating through the optical fiber 3a is converted into parallel light by the collimator lens 3b, condensed by the objective lens 3c, and incident on the substrate 1. Light from the incident portion 3 propagates through the substrate 1 and then enters the photonic crystal 2 from the bottom surface of the photonic crystal 2. Incident light 5 propagating through the photonic crystal 2 reaches the incident-side inclined surface 2a, is reflected, and propagates in the Z-axis direction. The propagating light 8 is preferably a band on the Brillouin zone boundary. The incident side inclined surface 2a may be provided with a reflective layer such as a metal or a dielectric multilayer film.

  The propagating light 8 propagating in the Z-axis direction reaches the exit side inclined surface 2b. The propagating light 8 is emitted as outgoing light 6a from the outgoing side inclined surface 2b.

  Further, the outgoing light 6 a is guided to the outgoing part 14. Specifically, the outgoing light 6a emitted from the substrate 1 proceeds in the order of the objective lens 14c and the collimating lens 14b, and enters the optical fiber 14a.

  The waveguide element 10a of the second embodiment has the same effect as that of the first embodiment. Further, the photonic crystal 2 may not include the emission side inclined surface 2b. Even if the end face on the exit side of the photonic crystal 2 is a vertical end face, the propagating light 8 by the band on the Brillouin zone boundary can be guided to the exit section 14 by installing a phase grating, for example. Further, in the waveguide element in which it is not necessary to take out the emitted light 6, it is not necessary to provide the emitting portion 14. For example, in a waveguide element in which incident light 5 is incident for use as control light or excitation light, the energy of propagation light 8 may be significantly attenuated. In such a case, there is no need to take out the emitted light 6, so there is no need to provide the emitting portion 14.

  In addition, what is necessary is just to obtain | require each condition in the waveguide element 10a of Embodiment 2 by band calculation.

(Embodiment 3)
A waveguide element according to Embodiment 3 of the present invention will be described with reference to the drawings. FIG. 9 is a side view showing the configuration of the waveguide element according to Embodiment 3 of the present invention. In FIG. 9, the refractive index periodic direction of the photonic crystal waveguide is the Y-axis direction, the light propagation direction is the Z-axis direction, and the Y-axis direction and the direction perpendicular to the Z-axis direction are the X-axis direction.

  In the waveguide element 10b according to the third embodiment, similarly to the waveguide element 10 according to the first embodiment, the propagation light 8 is reflected by the emission-side inclined surface 2b and the emission light 6 is emitted through the substrate 1. However, unlike the first embodiment, the incident light 5 a is directly incident on the photonic crystal 2 from the incident side inclined surface 2 a without passing through the substrate 1. Incident light 5 a incident on the photonic crystal 2 from the incident side inclined surface 2 a becomes propagation light 8 and propagates in the photonic crystal 2. That is, in the waveguide element 10 b of FIG. 9, the incident light 5 a is directly incident from the incident side inclined surface 2 a, and the emitted light 6 is emitted through the substrate 1. In FIG. 9, members having the same functions as the members shown in FIG.

  In the waveguide element 10b, incident light 5a is directly incident on the photonic crystal 2 from the incident-side inclined surface 2a. Therefore, the incident part 19 which injects the incident light 5a into the photonic crystal 2 is installed facing the incident side inclined surface 2a.

  Such an operation of the waveguide element 10b will be described. First, the incident light 5a that has propagated through the optical fiber 19a is converted into parallel light by the collimator lens 19b, collected by the objective lens 19c, and incident on the photonic crystal 2 from the incident side inclined surface 2a. Propagates in the Z-axis direction. The propagating light 8 is preferably a band on the Brillouin zone boundary.

  The propagating light 8 propagating in the Z-axis direction reaches the exit side inclined surface 2b. The propagating light 8 is reflected by the exit-side inclined surface 2 b and changes its path toward the bottom surface of the photonic crystal 2. In addition, you may provide reflective layers, such as a metal and a dielectric multilayer, for example in the output side inclined surface 2b.

  Further, the light that has been reflected by the outgoing-side inclined surface 2 b and becomes outgoing light 6 is emitted from the bottom surface of the photonic crystal 2. The outgoing light 6 from the photonic crystal 2 is incident on the substrate 1, propagates in the substrate 1, and is emitted from the substrate 1 to the outside. The outgoing light 6 emitted from the substrate 1 is guided to the outgoing part 4. Specifically, the outgoing light 6 emitted from the substrate 1 proceeds in the order of the objective lens 4c and the collimating lens 4b, and enters the optical fiber 4a. The emission unit 4 is installed at a position where light emitted from the substrate 1 is guided.

  The waveguide element 10b of the third embodiment has the same effect as that of the first embodiment. Further, the photonic crystal 2 may not include the incident side inclined surface 2a. Even if the incident-side end face of the photonic crystal 2 is a vertical end face, the propagating light 8 can be a band on the Brillouin zone boundary. For example, a phase grating may be installed so that incident light 5a is incident on the photonic crystal 2 via the phase grating. Further, in the waveguide element that does not require the incident light 5 to be incident, it is not necessary to provide the incident portion 19. For example, in a waveguide element that uses laser oscillation light generated by external energy as propagating light 8, it is not necessary to provide the incident portion 19.

  In addition, what is necessary is just to obtain | require each condition in the waveguide element 10b of Embodiment 3 by band calculation.

(Embodiment 4)
A waveguide element according to Embodiment 4 of the present invention will be described with reference to the drawings. FIG. 10 is a perspective view showing a configuration of a waveguide element according to Embodiment 4 of the present invention. In FIG. 10, the refractive index periodic direction of the photonic crystal waveguide is the X-axis direction, the light propagation direction is the Y-axis direction, and the X-axis direction and the direction perpendicular to the Y-axis direction are the Z-axis direction.

  The waveguide element 30 according to the fourth embodiment and the waveguide element 10 according to the first embodiment have substantially the same configuration except that the configuration of the photonic crystal is different. Accordingly, in FIG. 10, members having the same functions as those shown in FIG.

  In the waveguide element 30 according to the fourth embodiment of the present invention, the photonic crystal 32 is placed on the substrate 1. At both ends of the upper surface of the photonic crystal 32 (on the opposite side of the substrate 1), an incident side diffraction grating 32a and an emission side diffraction grating 32b are formed, respectively. Specifically, grooves are formed in the X-axis direction at equal intervals on the upper surface (surface parallel to the XZ plane) of the photonic crystal 32 having a multilayer structure, so that the incident-side diffraction grating 32a and the output-side diffraction are A lattice 32b is formed.

  The light path in the waveguide element 30 according to the fourth embodiment will be described. First, the incident portion 3 makes incident light 5 incident on the bottom surface (the surface facing the top surface) of the photonic crystal 32 via the substrate 1. Incident light 5 incident on the photonic crystal 32 is reflected by the incident-side diffraction grating 32 a, and propagated light 8 is generated in the photonic crystal 32 due to a band on the Brillouin zone boundary. The propagating light 8 is reflected by the exit side diffraction grating 32 b, and the exit light 6 is emitted from the bottom surface of the photonic crystal 32. The outgoing light 6 from the photonic crystal 32 enters the substrate 1, propagates through the substrate 1, and is emitted from the substrate 1 to the outside. The outgoing light 6 emitted from the substrate 1 is guided to the outgoing part 4.

  The design of the entrance-side diffraction grating 32a and the exit-side diffraction grating 32b and the design of the photonic crystal 32 are performed using band calculation. As a result, a condition for generating propagating light on the Brillouin zone boundary can be obtained.

  The photonic crystal 32 may include only one of the incident side diffraction grating 32a and the emission side diffraction grating 32b. In that case, the end face of the photonic crystal 32 on which the incident side diffraction grating 32a and the emission side diffraction grating 32b are not formed may be inclined. Further, a phase grating may be provided on the end face of the photonic crystal 32 on which the incident side diffraction grating 32a and the emission side diffraction grating 32b are not formed. Thereby, the light can be incident or the emitted light can be guided so as to propagate the propagation light by the band on the Brillouin zone boundary.

  Next, a specific example in which an optical circuit using any one of the waveguide elements 10, 10a, 10b, or 30 of the first to fourth embodiments and an electronic circuit are combined will be described. FIG. 11 is a perspective view for explaining a combination of an optical circuit and an electronic circuit using the waveguide element according to the present invention.

  As shown in FIG. 11, a lens array 41 in which a plurality of microlenses 41 a are arranged is installed above the electronic circuit 42. Further, an optical circuit 40 including a waveguide element having the same function as the waveguide element of the first embodiment is installed above the lens array 41.

  On the upper surface of the electronic circuit 42, a VCSEL (Vertical Cavity Semiconductor Emission Laser) 42 a that emits a vertical optical signal and a light receiving cell 42 b are disposed, and a conductor 42 c that inputs and outputs an electrical signal is disposed on the end surface.

  The optical circuit 40 is provided with a plurality of incident-side or emission-side inclined surfaces 40a. Although not shown, the optical circuit 40 includes a photonic crystal, and the inclined surface 40a is formed thereon. When light is incident on the inclined surface 40a, the light becomes propagating light on the Brillouin zone boundary, and light is emitted from the corresponding inclined surface 40a. Here, the microlens 41a corresponds to an incident part or an emission part.

  For example, signal light or control light is emitted from the VCSEL 42 a toward the lens array 41 by an electrical signal input to the electronic circuit 42. The light 43 enters the inclined surface 40a via the microlens 41a. The signal light or the control light is processed by the waveguide element and is emitted toward the lens array 41 from the inclined surface 40a different from the incident light. The light 43 is input to the light receiving cell 42b through the microlens 41a.

  With such a configuration, the advantages of both flexible electronic processing and high-speed processing using light can be used. Further, as shown in FIG. 11, since the optical circuit 40 and the electronic circuit 42 are separated from each other, each can be manufactured using completely different materials and processes, so that each can be manufactured efficiently without waste. Further, the optical circuit 40 and the electronic circuit 42 may be stacked and integrated on the same substrate.

  Although the waveguide element according to the first embodiment has been described, the waveguide elements according to the second, third, and second embodiments can be used in the same manner.

(Example)
The result of actually producing the waveguide device according to the first embodiment of the present invention and measuring the optical characteristics is shown below. FIG. 12 is a side view for explaining the configuration of the waveguide element in the embodiment. In addition, in the member used in FIG. 12, the same code | symbol is attached | subjected to the member which has the same function as the member used in FIG. 1 and FIG. The configuration of the waveguide element 50 will be described. The photonic crystal 2 as a core is formed by alternately stacking a plurality of Ta ₂ O ₅ thin films and SiO ₂ thin films on one side surface of a quartz parallel plane substrate 1 (100 mm × 20 mm × 1 mm) by vacuum deposition. Is done. The thickness of the Ta ₂ O ₅ thin film is 424 nm, and the thickness of the SiO ₂ thin film is 106 nm. Ten layers of these are formed, but the last thin film of SiO ₂ is the clad 51, and its thickness is about 2000 nm. In other words, in the embodiment, a SiO ₂ protective layer is formed as the clad 51 on the photonic crystal 2 having a nine-layer structure. From the above, the refractive index period of the photonic crystal 2 is 530 nm. Further, the width (length in the X-axis direction) of the photonic crystal 2 was 10 mm, and the length L was measured in two cases of 24.5 mm and 39.5 mm. Further, the end surface of the photonic crystal 2 is cut obliquely to form a polished surface so that the angles of the incident side inclined surface 2a and the outgoing side inclined surface 2b with respect to the XZ plane are 27 °, respectively, and the incident side inclined surface 2a And the output side inclined surface 2b was produced. Further, reflective layers 21a and 21b made of silver having a thickness of 150 nm were formed on the incident side inclined surface 2a and the emission side inclined surface 2b by vacuum deposition.

The incident portion 3 is a collimator lens that is an aspherical objective lens having a focal length of 11.3 mm, and that propagates through the optical fiber 3a which is a single mode fiber for communication (SMF, wavelength 1550 nm specification, numerical aperture NA = 0.1). In 3b, a parallel light beam is obtained. Further, the parallel light beam is made into a linear focal point by an objective lens 3c which is a cylindrical plano-convex lens (material is optical glass BK7, center thickness 3.8 mm, focal point distance 3.9 mm) having a curvature radius of 2.0 mm. This linear focal point was incident perpendicularly to the bottom surface (a surface parallel to the XZ plane) of the photonic crystal 2. That is, the angle formed by the bottom surface of the photonic crystal 2 and the incident light 5 is 90 °. The reason why the focal point is linear is that the photonic crystal 2 serving as a waveguide has a slab shape. The exit unit 4 uses the same optical system as that of the entrance unit 3 in reverse to extract the exit light. Note that the band diagram of the photonic crystal according to this example has the shape shown in FIGS. 4 and 6 at a frequency corresponding to λ ₀ = 1550 nm. The SMF on the incident side and the outgoing side was connected to an optical vector analyzer (OVA-CT type manufactured by Luna Technologies Inc., USA), and the optical characteristics of the waveguide element 50 (all elements of Jones matrix) were evaluated.

  The measurement results of the above examples are shown below.

  FIG. 13 is a graph showing an impulse response when L = 24.5 mm in the example. FIG. 14 is a graph showing an impulse response when L = 39.5 mm in the example. In FIGS. 13 and 14, the horizontal axis represents the delay time, and the vertical axis represents the amplitude. In both FIG. 13 and FIG. 14, although a mode peak that becomes noise is slightly observed, it can be seen that the propagation is caused by almost a single mode (a mode on the Brillouin zone boundary). Thus, the waveguide element 50 of the embodiment can propagate a mode on the Brillouin zone boundary in a single mode.

  FIG. 15 is a graph showing insertion loss in the example when L = 24.5 mm. FIG. 16 is a graph showing the insertion loss in the example when L = 39.5 mm. 15 and 16, the horizontal axis represents wavelength and the vertical axis represents insertion loss. From FIG. 15, the insertion loss at the peak wavelength when L = 24.5 mm is 19.8 dB. Also, from FIG. 16, the insertion loss at the peak wavelength when L = 39.5 mm is 28.7 dB.

  In the embodiment, the incident light and the outgoing light are perpendicular to the substrate. However, it is possible to easily change the incident angle and the outgoing angle by changing the paths of the incident light and the outgoing light.

  The waveguide element of the present invention is preferably mounted on an optical circuit. By combining the optical circuit and the electronic circuit, a circuit that takes advantage of the advantages of the optical circuit and the electronic circuit can be manufactured.

The perspective view which shows the structure of the waveguide element which concerns on Embodiment 1 of this invention. The side view which shows the structure of the waveguide element which concerns on Embodiment 1 of this invention. The side view explaining the course of the light of the incident side of the waveguide element which concerns on Embodiment 1 of this invention Band diagram corresponding to FIG. The side view explaining the course of the light of the output side of the waveguide element which concerns on Embodiment 1 of this invention Band diagram corresponding to FIG. The side view which shows the structure of the waveguide element provided with the reflection layer which concerns on Embodiment 1 of this invention. The side view which shows the structure of the waveguide element which concerns on Embodiment 2 of this invention. Side view showing the configuration of the waveguide device according to the third embodiment of the present invention. The perspective view which shows the structure of the waveguide element which concerns on Embodiment 2 of this invention. The perspective view for demonstrating the combination of the optical circuit and electronic circuit using the waveguide element by this invention Side view for explaining the configuration of the waveguide element in the embodiment In an Example, the graph which shows an impulse response in case of L = 24.5mm In an Example, the graph which shows an impulse response in case of L = 39.5mm In an Example, the graph which shows the insertion loss in case of L = 24.5mm In an Example, the graph which shows the insertion loss in case of L = 39.5mm It is a perspective view which shows the structure which couple | bonded the optical circuit and the electronic circuit, Fig.17 (a) is a figure which shows end surface coupling | bonding, FIG.17 (b) is a figure which shows vertical coupling | bonding.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Substrate 2, 32 Photonic crystal 2a Incident side inclined surface 2b Output side inclined surface 3, 19 Incident part 3a, 4a, 14a, 19a Optical fiber 3b, 4b, 14b, 19b Collimator lens 3c, 4c, 14c, 19c Objective lens 4, 14 Emission part 5, 5b Incident light 6, 6a Emission light 7a, 7b, 9a, 9b Refracted light 8 Propagating light 10, 10a, 10b, 30, 50, 60 Waveguide element 11, 12, 16, 17 Broken line 13 , 18 lines 21a, 21b Reflective layer 32a Incident side diffraction grating 32b Outgoing side diffraction grating 40 Optical circuit 40a Inclined surface 41 Lens array 41a Micro lens 42 Electronic circuit 42a VCSEL
42b Light receiving cell 42c Conductor wire 43 Light 51 Clad 100 Electronic circuit 101 Conductor wire 102, 201 End surface 103, 202 Main surface 200 Optical circuit 300 Light

Claims (13)

A laminated body having refractive index periodicity in one direction, and having a bottom surface perpendicular to the refractive index periodic direction, an incident side inclined surface and an output side inclined surface inclined with respect to the bottom surface; A waveguide device comprising a photonic crystal as a core, an incident part, and an emission part,
The incident portion causes light to be incident on the bottom surface of the photonic crystal;
The light incident on the photonic crystal is reflected by the incident-side inclined surface, and light propagated by a band on the Brillouin zone boundary is generated in the photonic crystal,
The propagating light is reflected by the exit side inclined surface, and light is emitted from the bottom surface of the photonic crystal,
A waveguide element in which light emitted from the photonic crystal is guided to the emitting portion. A photonic crystal as a core, which is a laminate having a refractive index periodicity in one direction and has a bottom surface perpendicular to the refractive index periodic direction and an inclined surface inclined with respect to the bottom surface; A waveguide element comprising an incident part,
The incident portion causes light to be incident on the bottom surface of the photonic crystal;
A waveguide element in which light incident on the photonic crystal is reflected by the inclined surface, and propagating light is generated in the photonic crystal by a band on a Brillouin zone boundary. A photonic crystal as a core, which is a laminate having a refractive index periodicity in one direction and has a bottom surface perpendicular to the refractive index periodic direction and an inclined surface inclined with respect to the bottom surface; A waveguide element comprising an output part,
The propagating light by the band on the Brillouin zone boundary propagating in the photonic crystal is reflected by the inclined surface, and light is emitted from the bottom surface of the photonic crystal,
A waveguide element in which light emitted from the photonic crystal is guided to the emitting portion.   The waveguide element according to claim 1, wherein a reflection layer is formed on each of the incident side inclined surface and the emission side inclined surface.   The waveguide element according to claim 2, wherein a reflective layer is formed on the inclined surface.   The waveguide element according to claim 4, wherein the reflective layer is a metal film.   The waveguide element according to claim 4, wherein the reflective layer is a dielectric multilayer film. A laminated body having a refractive index periodicity in one direction, a bottom surface perpendicular to the refractive index periodic direction, a top surface facing the bottom surface, an incident side diffraction grating and an output side diffraction formed on the top surface A waveguide element having a photonic crystal as a core having a lattice, an incident part, and an emission part,
The incident portion causes light to be incident on the bottom surface of the photonic crystal;
Light incident on the photonic crystal is reflected by the incident-side diffraction grating, and light propagated by a band on the Brillouin zone boundary is generated in the photonic crystal,
The propagating light is reflected by the emission side diffraction grating, and light is emitted from the bottom surface of the photonic crystal,
A waveguide element in which light emitted from the photonic crystal is guided to the emitting portion. A core having a refractive index periodicity in one direction and having a bottom surface perpendicular to the refractive index periodic direction, a top surface facing the bottom surface, and a diffraction grating formed on the top surface; A waveguide device having a photonic crystal and an incident part,
The incident portion causes light to be incident on the bottom surface of the photonic crystal;
A waveguide element in which light incident on the photonic crystal is reflected by the diffraction grating, and propagation light is generated in the photonic crystal by a band on a Brillouin zone boundary. A core having a refractive index periodicity in one direction and having a bottom surface perpendicular to the refractive index periodic direction, a top surface facing the bottom surface, and a diffraction grating formed on the top surface; A waveguide device comprising a photonic crystal and an emission part,
Light propagated by a band on a Brillouin zone boundary propagating in the photonic crystal is reflected by the diffraction grating, and light is emitted from the bottom surface of the photonic crystal,
A waveguide element in which light emitted from the photonic crystal is guided to the emitting portion.   The traveling direction of light incident on the photonic crystal or the traveling direction of light emitted from the photonic crystal is the same direction as the refractive index periodic direction of the photonic crystal. A waveguide element according to any one of claims 4 and 8.   The waveguide element according to claim 2 or 9, wherein a traveling direction of light incident on the photonic crystal is the same direction as the refractive index periodic direction of the photonic crystal.   The waveguide element according to claim 3 or 10, wherein a traveling direction of light emitted from the photonic crystal is the same direction as the refractive index periodic direction of the photonic crystal.

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