Abstract: In an optical device, a slab layer has an active layer sandwiched between two cladding layers. Periodic air holes are present in the slab layer. A linear defect region is present in a part of the air hole structures. As a result, laser oscillation is generated at the band end in a two-dimensional photonic crystal waveguide mode.

Abstract: The present invention intends to provide a two-dimensional photonic crystal having a high level of mechanical strength and functioning as a high-efficiency resonator. The two-dimensional photonic crystal according to the present invention includes a slab layer 31 under which a clad layer 32 is located. In the slab layer 31, areas 35 having a refractive index different from that of the slab layer 31 are cyclically arranged to create a two-dimensional photonic crystal. A portion of the cyclic arrangement of the areas 35 are omitted to form a point-like defect 36. This defect 36 functions as a resonator at which a specific wavelength of light resonates. An air-bridge cavity 37 facing the point-like defect 36 is formed over a predetermined range of the clad layer 32. In this construction, the clad layer 32 supports the slab layer 31 except for the range over which the air-bridge space 37 is formed. Therefore, the two-dimensional photonic crystal has a high level of mechanical strength.

Abstract: An optical delay circuit includes a plurality of defect waveguides arranged in parallel and including a line-shaped defect in a periodic refractive-index distribution structure of a photonic crystal. The defect waveguides include a multiplexing/demultiplexing portion in which the defect waveguides are arranged close to each other to multiplex and demultiplex light; and an optical delay portion extending from the multiplexing/demultiplexing portion, in which the defect waveguides are arranged with a predetermined distance therebetween so that light propagating in any of the defect waveguides does not interfere with light propagating in the other defect waveguides. Each of the waveguides has a different configuration.

Abstract: In this electromagnetic wave frequency filter, an electromagnetic wave of a predetermined frequency matching a resonant frequency of a resonator 41 is transmitted from an input waveguide 2 to an output waveguide 3 through the resonator 41, and is outputted from a drop port P31. This filter has an input-waveguide-side reflector 211 and an output-waveguide-side reflector 311, which reflect the electromagnetic wave of the predetermined frequency. The electromagnetic wave frequency filter satisfies the following relation: Qinb/(1?cos ?1)<<QV, Qinb/(1?cos ?1)=Qinr/(1?cos ?2), ?1, ?2?2N? (N=0, 1, . . .

Abstract: The Q factor and electric field pattern (radiation pattern) for a cavity made from a donor-type point defect 4 as is illustrated in FIG. 1 were simulated by the FDTD method. The simulation parameters were configured by selecting silicon for the slab 1; and setting approximately 1.55 ?m, which is generally used in optical communications, for the wavelength ?; 0.42 ?m for the lattice constant a; 0.6a for the slab 1 thickness; and 0.29a for the predetermined sectional radius of the through-holes 2.

Abstract: An object of the present invention is to provide a multiplexer/demultiplexer capable of preventing a decrease in multiplexing/demultiplexing efficiency due to an error in wavelength or due to a crosstalk with other wavelengths. A two-dimensional photonic crystal having holes 22 cyclically arranged is provided with an input waveguide 23 and an output waveguide 24. Located between the two waveguides are two point-like defects 25 and 26, each consisting of a region devoid of the holes 22. From the light including various wavelengths and propagating through the input waveguide 23, the two point-like defects extract a ray of light having a wavelength determined by the shape of the point-like defects and introduce it into the output waveguide 24.

Abstract: A semiconductor device has a two-dimensional slab photonic crystal structure in which a substrate supports a sheet-like slab layer including, sequentially stacked, a lower cladding layer, an active layer, and an upper cladding layer. A periodic refractive index profile structure, in surfaces of the stacked layers, introduces a linear defect region that serves as a waveguide. A p-type region and an n-type region in the slab layer define a pn junction surface at a predetermined angle with respect to the surfaces of the stacked layers in the slab layer.

Abstract: The channel add/drop filter includes first and second 2D photonic crystals, and the first 2D photonic crystal includes a first waveguide and a first cavity, with the first cavity acting to take in light of a specific wavelength from the first waveguide and radiate it outside the first photonic crystal, and the second 2D photonic crystal includes a second waveguide with substantially the same characteristics as the first waveguide and a second cavity with substantially the same characteristics as the first cavity. The first and second waveguides are optically connected so that when the principal plane of the first 2D photonic crystal and the electric-field vector of the light within the first waveguide torn, an arbitrary angle ?, the principal plane of the second 2D photonic crystal and the electric-field vector of the light within the second waveguide form an angle of ?+(?/2).

Abstract: The present invention aims to provide an electromagnetic wave frequency filter capable of transmitting an electromagnetic wave having a predetermined frequency between two waveguides with a high level of efficiency. This object is achieved by the following construction: A resonator 15 that resonates with the electromagnetic wave having the predetermined frequency is located between an input waveguide 13 and an output waveguide 14 and close to the two waveguides. The output waveguide 14 is designed so that it extends parallel to the input waveguide 13 within a predetermined section 18 located in proximity to the resonator 15, and its distance from the input waveguide 13 in the other section is larger than that in the predetermined section 18.

Abstract: A semiconductor device has a two-dimensional slab photonic crystal structure in which a substrate supports a sheet-like slab layer including, sequentially stacked, a lower cladding layer, an active layer, and an upper cladding layer. A periodic refractive index profile structure, in surfaces of the stacked layers, introduces a linear defect region that serves as a waveguide. A p-type region and an n-type region in the slab layer define a pn junction surface at a predetermined angle with respect to the surfaces of the stacked layers in the slab layer.

Abstract: The present invention has been made to provide an optical multiplexer/demultiplexer with a high multiplexing and demultiplexing efficiency. The object is achieved as follows. In an in-plane heterostructure photonic crystal in which vacancies 32 are periodically arranged in each of forbidden band zones 301, 302, . . . with different cycle distances, a waveguide 33 is formed passing through all the forbidden band zones by rendering corresponding vacancies 32 defective in a linear arrangement, and point-like defects 341, 342, . . . are formed by rendering three vacancies 32 in a linear arrangement defective in each of the forbidden band zones.

Abstract: The present invention aims to provide a two-dimensional photonic crystal having an optical resonator, which allows the control of the front/back emission ratio of light. To achieve this object, a refractive index member (13) made of a material having a refractive index different from that of air is mounted on a two-dimensional photonic crystal having a body (11) in which holes (12) are periodically arranged. In this construction, the body (11) and the refractive index member (13) cooperatively function as an optical resonator located at the position where the refractive index member (13) is mounted. The light emitted from this optical resonator is stronger on the side having a higher refractive index, i.e. on the side where the refractive index member is mounted. Accordingly, the light (191) emitted from the side where the refractive index member (13) is mounted is stronger than the light (192) emitted from the other side. The ratio of the emission intensity of the two rays of light (191) and (192), i.e.

Abstract: The present invention provides a two-dimensional photonic crystal optical resonator and reflector having high light-extracting efficiency. A two-dimensional photonic crystal consisting of a slab-shaped body is created by periodically arranging holes having a refractive index different from that of the body. A waveguide is formed by providing a linear zone where no hole is bored. Two acceptor type point defects are formed by enlarging two holes spaced apart from each other by a distance L in the longitudinal direction of the waveguide. An appropriate selection of the distance L suppresses or increases the reflection and transmission of light at the point defects, allowing an efficient extraction of light resonating at the point defects. This allows the body to be used as an optical resonator for producing a resonance of light between the two point defects or optical reflector for reflecting light at the two point defects.

Abstract: An optical delay circuit includes a plurality of defect waveguides arranged in parallel and including a line-shaped defect in a periodic refractive-index distribution structure of a photonic crystal. The defect waveguides include a multiplexing/demultiplexing portion in which the defect waveguides are arranged close to each other to multiplex and demultiplex light; and an optical delay portion extending from the multiplexing/demultiplexing portion, in which the defect waveguides are arranged with a predetermined distance therebetween so that light propagating in any of the defect waveguides does not interfere with light propagating in the other defect waveguides. Each of the waveguides has a different configuration.

Abstract: The present invention has been devised to provide a two-dimensional photonic crystal optical resonator and optical reflector having high light-extracting efficiency. This is achieved by the following construction. A two-dimensional photonic crystal consisting of a slab-shaped body 11 is created by periodically arranging areas (or holes) 12 having a refractive index different from that of the body 11. A waveguide 13 is formed by providing a linear zone where no hole 12 is bored. Two acceptor type point defects 14 are formed by enlarging two holes 12 spaced apart from each other by a distance L in the longitudinal direction of the waveguide. In this construction, an appropriate selection of the distance L suppresses the reflection and transmission of light at the point defects 14, allowing an efficient extraction of light resonating at the point defects 14. An appropriate selection of the distance L will increase the reflectivity of light at the point defects 14.

Abstract: The present invention provides an optical multiplexer/demultiplexer that can be smaller in size and higher in Q-factor or efficiency. This object is achieved by the following construction. In a slab-shaped body 11, low refractive index areas 12 having a refractive index lower than that of the material of the body 11 are periodically arranged to construct a two-dimensional photonic crystal, in which a waveguide 13 is formed by not boring holes 12 linearly. A donor type cluster defect 14 is formed by not boring holes 12 at two ore more lattice points located adjacent to the waveguide 13. With this construction, only a specific wavelength of light included in the light propagating through the waveguide 13 resonates at the donor type cluster 14, and the light thus trapped is released to the outside (demultiplexing). Conversely, only a specific wavelength of light may be introduced through the donor type cluster defect 14 into the waveguide 13 (multiplexing).

Abstract: A two-dimensional photonic crystal slab having a photonic band gap common to a light beam in the TE-like mode and a light beam in the TM-like mode includes a slab member containing a high refractive index material and low refractive index sectors, arranged in the slab member in a triangular pattern, having a triangular prism shape. The two-dimensional photonic crystal slab further includes a linear defect section that is a disordered portion in a periodic structure of a photonic crystal and extends in the ?-J direction. Light beams in the TE-like mode and light beams in the TM-like mode can be propagated through the waveguide section. A two-dimensional photonic crystal waveguide includes the two-dimensional photonic crystal slab.

Abstract: A semiconductor device has a two-dimensional slab photonic crystal structure in which a substrate supports a sheet-like slab layer including, sequentially stacked, a lower cladding layer, an active layer, and an upper cladding layer. A periodic refractive index profile structure, in surfaces of the stacked layers, introduces a linear defect region that serves as a waveguide. A p-type region and an n-type region in the slab layer define a pn junction surface at a predetermined angle with respect to the surfaces of the stacked layers in the slab layer.

Abstract: In an optical device, a slab layer includes an active layer sandwiched between cladding layers. The slab layer has a periodic refractive index profile structure in a two-dimensional plane, as a two-dimensional slab photonic crystal structure, and a linear defect region serving as a waveguide in the periodic refractive index profile structure. Regions having different widths of the waveguides, as segments of the waveguide, are connected in series.

Abstract: Two-dimensional photonic crystal surface-emitting laser comprising a two-dimensional photonic crystal, having media different in refractive index arrayed in a two-dimensional cycle, disposed in the vicinity of an active layer that emits light by the injection of carriers, wherein the two-dimensional photonic crystal consists of square lattices having equal lattice constants in perpendicular directions, and a basic lattice consisting of a square with one medium as a vertex has an asymmetric refractive index distribution with respect to either one of the two diagonals of the basic lattice to thereby emit light in a constant polarizing direction.