Abstract: The three-dimensional structure includes first and second waveguides, a resonator, a first region. The waveguides cause light to propagate therein in a first guide mode. The second waveguide and the first region are mutually connected such that at least part of the light propagating in the second waveguide is coupled with light propagating in the first region in a guide mode different from the first guide mode. Light present in the resonator is coupled with the lights respectively propagating in the waveguides. A condition of ?1?cos(?)<0 is satisfied, where ? represents a phase difference between one of first and second lights whose intensity is higher than that of the other and third light. The first light is light reflected at a connection region between the first waveguide and the resonator. The second and third lights are lights coupled with the light present in the resonator and propagate in the waveguides.

Abstract: The three-dimensional structure includes first and second waveguides, a resonator, a first region. The waveguides cause light to propagate therein in a first guide mode. The second waveguide and the first region are mutually connected such that at least part of the light propagating in the second waveguide is coupled with light propagating in the first region in a guide mode different from the first guide mode. Light present in the resonator is coupled with the lights respectively propagating in the waveguides. A condition of ?1?cos(?)<0 is satisfied, where ? represents a phase difference between one of first and second lights whose intensity is higher than that of the other and third light. The first light is light reflected at a connection region between the first waveguide and the resonator. The second and third lights are lights coupled with the light present in the resonator and propagate in the waveguides.

Abstract: A waveguide based on a three-dimensional photonic crystal is arranged to provide wave-guiding in a single mode and a mode having a field strength distribution with unimodality in a plane perpendicular to the wave-guiding direction, to thereby enable wave-guiding in a desired frequency band, wherein the three-dimensional photonic crystal has a plurality of line defect members which include a first line defect member made of a medium having a refractive index not smaller than that of the columnar structures and formed in a direction perpendicular to the direction in which the columnar structures extend, and a second line defect member formed in the same direction as the first line defect member.

Abstract: The three-dimensional structure includes a first waveguide (line defect) in a three-dimensional photonic crystal formed by periodically arranging first and second media, which causes light to propagate therein in a first guide mode, a second waveguide (line defect) in the three-dimensional photonic crystal, which causes light to propagate therein in a second guide mode, reflective portions provided in the first and second waveguides to reflect parts of the lights propagating in the first and second waveguides, and a first region connected to the second waveguide so as to cause at least part of the light that has propagated in the second waveguide via the reflective portion to propagate therein in a third guide mode. The reflective portions are formed of media having refractive indexes different from those the first and second waveguides. Each reflective portion has a homogeneous refractive index distribution in an entire section orthogonal to a waveguide-extending direction.

Abstract: At least one exemplary embodiment is directed to a method for fabricating a three-dimensional photonic crystal. In the method for fabricating the three-dimensional photonic crystal, a plurality of layers can be defined as one unit, and the total thickness of the one unit can be controlled such that an average layer-thickness of the plurality of layers in the one unit is about equal to the ideal layer-thickness so that a photonic band-gap occurs in a desired wavelength region.

Abstract: A resonator is provided which is produced by a defect formed in a three-dimensional photonic crystal. The three-dimensional photonic crystal can include layers containing a plurality of columnar structures with discrete structures in sublayers.

Abstract: A waveguide based on a three-dimensional photonic crystal is arranged to provide wave-guiding in a single mode and a mode having a field strength distribution with unimodality in a plane perpendicular to the wave-guiding direction, to thereby enable wave-guiding in a desired frequency band, wherein the three-dimensional photonic crystal has a plurality of line defect members which include a first line defect member made of a medium having a refractive index not smaller than that of the columnar structures and formed in a direction perpendicular to the direction in which the columnar structures extend, and a second line defect member formed in the same direction as the first line defect member.

Abstract: At least one exemplary embodiment is directed to a method for fabricating a three-dimensional photonic crystal. In the method for fabricating the three-dimensional photonic crystal, a plurality of layers can be defined as one unit, and the total thickness of the one unit can be controlled such that an average layer-thickness of the plurality of layers in the one unit is about equal to the ideal layer-thickness so that a photonic band-gap occurs in a desired wavelength region.

Abstract: At least one exemplary embodiment is directed to a waveguide including a plurality of linear defects of a three-dimensional photonic crystal, the plurality of linear defects include a first defect formed by changing the medium of some of columnar structures to a medium different from that of the columnar structures and a second linear defect formed by shifting the position or changing the shape of some of the columnar structures extending in the same direction as the first linear defect, and the first linear defect and the second linear defect are disposed apart by 0.5 times the out-of-plane lattice period or more in the stacking direction of the three-dimensional photonic crystal.

Abstract: At least one exemplary embodiment is directed to a method for manufacturing a three-dimensional photonic crystal including a plurality of stacked layers having periodic structures where the thickness of the periodic structures in a layer are adjusted such that the layer satisfies the following equation: neff1×H1×M=neff×H wherein H1 represents the actual thickness of the layer, neff1 represents the actual refractive index of the periodic refractive index structure, H represents the design thickness of the layer, neff represents the design effective refractive index of the periodic refractive index structure, and M represents a coefficient inclusive and between 0.5 and 2.0.

Abstract: A three-dimensional photonic crystal has periodic-refractive-index structures including a first layer having a periodic structure based on a first rectangular lattice having a period of A along a first axis and a period of B along a second axis orthogonal to the first axis in the plane direction, a second layer having a periodic structure disposed at a position shifted by +3B/8 along the second axis with respect to the position of the first rectangular lattice, a third layer having a periodic structure disposed at a position shifted by A/2 along the first axis and B/2 along the second axis with respect to the position of the periodic structure in the first layer, and a fourth layer having a periodic structure disposed at the same position as the periodic structure in the second layer.

Abstract: A three-dimensional photonic crystal of the present invention has a complete photonic band gap in a wide wavelength region and that can be easily produced. A three-dimensional photonic crystal in which a plurality of layers including a periodic-refractive-index structure are periodically stacked includes, a first layer having holes provided at lattice points of a first rectangular lattice and a second rectangular lattice, a second layer having columnar structures at lattice points of a face-centered rectangular lattice, a third layer having a periodic structure the same as that of the first layer and disposed at a shifted position, and a fourth layer having a periodic structure the same as that of the second layer.

Abstract: A three-dimensional photonic crystal has periodic-refractive-index structures including a first layer having a periodic structure based on a first rectangular lattice having a period of A along a first axis and a period of B along a second axis orthogonal to the first axis in the plane direction, a second layer having a periodic structure disposed at a position shifted by +3B/8 along the second axis with respect to the position of the first rectangular lattice, a third layer having a periodic structure disposed at a position shifted by A/2 along the first axis and B/2 along the second axis with respect to the position of the periodic structure in the first layer, and a fourth layer having a periodic structure disposed at the same position as the periodic structure in the second layer.

Abstract: At least one exemplary embodiment is directed to a waveguide including a plurality of linear defects of a three-dimensional photonic crystal, the plurality of linear defects include a first defect formed by changing the medium of some of columnar structures to a medium different from that of the columnar structures and a second linear defect formed by shifting the position or changing the shape of some of the columnar structures extending in the same direction as the first linear defect, and the first linear defect and the second linear defect are disposed apart by 0.5 times the out-of-plane lattice period or more in the stacking direction of the three-dimensional photonic crystal.

Abstract: At least one exemplary embodiment is directed to a waveguide, which includes a three-dimensional photonic crystal including a first linear defect and a second linear defect. The first linear defect is disposed at part of columnar structures and is formed of a medium different from the columnar structures. The second linear defect is disposed at part of columnar structures extending in the longitudinal direction of the first linear defect and is formed of a medium having a refractive index different from that of the medium used for the columnar structures. The second linear defect is separated from the first linear defect by a distance of at least 0.5 times the out-of-plane lattice period of the three-dimensional photonic crystal in a direction in which layers including the columnar structures are stacked.

Abstract: A three-dimensional photonic crystal of the present invention has a complete photonic band gap in a wide wavelength region and that can be easily produced. A three-dimensional photonic crystal in which a plurality of layers including a periodic-refractive-index structure are periodically stacked includes, a first layer having holes provided at lattice points of a first rectangular lattice and a second rectangular lattice, a second layer having columnar structures at lattice points of a face-centered rectangular lattice, a third layer having a periodic structure the same as that of the first layer and disposed at a shifted position, and a fourth layer having a periodic structure the same as that of the second layer.

Abstract: Provided is a resonator using a three-dimensional photonic crystal. In the resonator, a range of choice of a resonance wavelength is wide and a desirable electric field distribution is obtained. The resonator according to the present invention includes a plurality of point defects provided in the three-dimensional photonic crystal. At least one of the plurality of point defects does not include a eigenmode in a photonic band gap of the three-dimensional photonic crystal.

Abstract: A three-dimensional photonic crystal operating at a plurality of design wavelengths, in which the photonic band gap can be adjusted to a desired wavelength band without changing the lattice period, and an optical element that can contain a defect resonator or a defect waveguide in the three-dimensional photonic crystal are provided.

Abstract: At least one exemplary embodiment is directed to a method for fabricating a three-dimensional photonic crystal. In the method for fabricating the three-dimensional photonic crystal, a plurality of layers can be defined as one unit, and the total thickness of the one unit can be controlled such that an average layer-thickness of the plurality of layers in the one unit is about equal to the ideal layer-thickness so that a photonic band-gap occurs in a desired wavelength region.

Abstract: A three-dimensional photonic crystal includes a first region including a first layer, a second layer, a third layer, a fourth layer and a second region including the first layer, the second layer, the third layer, the fourth layer, and additional layers including discrete structures spaced from each other. The horizontal interval and the vertical interval of the rod-shaped structures in the first region are the same as those of the rod-shaped structures in the second region, respectively.