Abstract: A network system includes a network architecture including: a network layer configured to define an entirety of an electric power network constituted from electric power grids; a local network layer configured to define a local network corresponding to electric power grid groups and forming a part of the electric power network; a grid layer configured to define the electric power grids; a physical layer configured to define constituent elements included in the electric power grids; a first layer configured to define the information communication network that is associated with the network layer; a second layer configured to define the information communication network that is associated with the local network layer; a third layer configured to define the information communication network that is associated with the grid layer; and space, a fourth layer configured to define the information communication network that is associated with the physical layer.

Abstract: A power system includes: a direct-current bus to which a power generation device and a plurality of power devices are connected; and a plurality of battery devices connected at predetermined intervals from one end of the direct-current bus to another end and configured to supply and receive power to and from the direct-current bus.

Abstract: A network system includes: a wireless base station configured to relay communication performed by wireless terminals; distributed antennas each being configured to be connected to the wireless base station and form a cell that enables communication with the wireless terminals; direct-current grids each being arranged in a predetermined form in a communication area formed by the cells and configured to interchange power with power devices connected to the subject direct-current grid; a power gate arranged between the direct-current grids located adjacent to each other and configured to interchange power between the adjacent direct-current grids; and a control device configured to control the power gate based on information acquired from the power devices via the distributed antennas. The power devices connected to the direct-current grids are configured to perform communication with the control device via the distributed antennas that form the communication area including the direct-current grids.

Abstract: A composite optical waveguide 1 includes a first optical waveguide 9 comprising a silica-based core and a second optical waveguide 11 comprising an Si-based core. The second optical waveguide 11 is joined to the first optical waveguide 9. The length of the first optical waveguide 9 corresponds to a permissible propagation loss of the second optical waveguide 11. The second optical waveguide 11 includes a sharply curved portion 13 having a radius smaller than the minimum bend radius of the first optical waveguide 9.

Abstract: A waveguide structure includes core 1 formed of a semiconductor such as Si, two external regions 2 which are not optically connected to the core but arranged at a certain distance from the core and bridges 3 which electrically connect the external regions to the core. Light propagating in the waveguide core is strongly confined in the waveguide core and optically disconnected from (i.e. not coupled with) the external regions, so that light can propagate in the waveguide without being affected by the existence of the external regions. Furthermore, the waveguide core is electrically connected to the external regions through the bridges, so that a voltage can be applied and a current can be caused to flow to the core from the external regions.

Abstract: A composite optical waveguide 1 includes a first optical waveguide 9 comprising a silica-based core and a second optical waveguide 11 comprising an Si-based core. The second optical waveguide 11 is joined to the first optical waveguide 9. The length of the first optical waveguide 9 corresponds to a permissible propagation loss of the second optical waveguide 11. The second optical waveguide 11 includes a sharply curved portion 13 having a radius smaller than the minimum bend radius of the first optical waveguide 9.

Abstract: A waveguide structure comprises a core (1) composed of a semiconductor such as Si; two external regions (2) which are not optically coupled with the core but arranged at a certain distance from the core; and a bridge (3) electrically connecting the external regions with the core. Since light propagating in the waveguide core is strongly confined within the waveguide core and is optically disconnected (not coupled) with the external regions, the light can propagate in the waveguide without being affected by the existence of the external regions. Furthermore, since the waveguide core is electrically connected with the external regions through the bridge, a voltage can be applied and a current can be carried to the core from the external regions.

Abstract: In an optical circuit including multi-dimensional photonic crystals, in which the optical circuit has a structure (33), such as a light emitting member or a light receiving member, having a natural resonance frequency, another structure (34) having a natural resonance frequency slightly differing from the natural resonance frequency of the structure (33) is arranged in the vicinity of the structure (33) to control the directivity of localization and propagation of an electromagnetic field, light emission and light reception in a spatial region including the above structures in the multi-dimensional photonic crystals, in order to permit functional operations to be realized.

Abstract: There is provided an optical device and an optical waveguide composed of a photonic crystal in which two optical waveguide modes that are orthogonal to a light propagation direction can be used, whereby design latitude is increased. In the optical waveguide device composed of a photonic crystal, in a dispersion relationship of the photonic crystal, light is propagated using a refractive index guide mode that is a minimum frequency optical waveguide mode. Alternatively, two optical waveguide modes that are orthogonal to light propagation direction are used, a linear defect waveguide mode is used for the first optical waveguide mode; and light is propagated in the second light guide mode by using a refractive index guide mode that is a minimum frequency optical waveguide mode in a dispersion relationship of the photonic crystal.

Abstract: In an optical circuit including multi-dimensional photonic crystals, in which the optical circuit has a structure (33), such as a light emitting member or a light receiving member, having a natural resonance frequency, another structure (34) having a natural resonance frequency slightly differing from the natural resonance frequency of the structure (33) is arranged in the vicinity of the structure (33) to control the directivity of localization and propagation of an electromagnetic field, light emission and light reception in a spatial region including the above structures in the multi-dimensional photonic crystals, in order to permit functional operations to be realized.

Abstract: A waveguide structure having a cross-sectional structure wherein Si is in the center and it is surrounded by a peripheral material, which is either SiO2 or a polymer material. The above-mentioned peripheral material functions as a cladding.

Abstract: In an optical circuit including multi-dimensional photonic crystals, in which the optical circuit has a structure (33), such as a light emitting member or a light receiving member, having a natural resonance frequency, another structure (34) having a natural resonance frequency slightly differing from the natural resonance frequency of the structure (33) is arranged in the vicinity of the structure (33) to control the directivity of localization and propagation of an electromagnetic field, light emission and light reception in a spatial region including the above structures in the multi-dimensional photonic crystals, in order to permit functional operations to be realized.

Abstract: A nonlinear-optic waveguide device has a thin-wire optical waveguide including a core having a cross-sectional area of at most 1 ?m2 and a cladding, the core and the cladding having a refractive index difference of at least 1. A light pulse introduced into the core has a peak power of at least several hundreds W and a pulse duration of at most 10 ps. The thin-wire optical waveguide has a length of about 1 cm. The nonlinear optical device, a mode-locked semiconductor laser, and tunable optical filter are combined into a white pulse light source.

Abstract: A nonlinear-optic waveguide device has a thin-wire optical waveguide including a core having a cross-sectional area of at most 1 ?m2 and a cladding, the core and the cladding having a refractive index difference of at least 1. A light pulse introduced into the core has a peak power of at least several hundreds W and a pulse duration of at most 10 ps. The thin-wire optical waveguide has a length of about 1 cm. The nonlinear optical device, a model-locked semiconductor laser, and tunable optical filter are combined into a white pulse light source.

Abstract: A waveguide structure having a cross-sectional structure wherein Si is in the center and it is surrounded by a peripheral material, which is either SiO2 or a polymer material. The above-mentioned peripheral material functions as a cladding.

Abstract: The present invention provides a photonic crystal waveguide comprising: a substrate; a bottom cladding layer over the substrate; and a core layer over the bottom cladding layer, the core layer having a uniform distribution of holes, wherein the core layer has at least a waveguide region which is thicker than a remaining region of the core layer to cause a refractive index guide effect, or wherein the core layer has at least a waveguide region, on which a dielectric pattern is provided which has a refractive index higher than a substance in contact with a top surface of the core layer, or wherein the core layer has at least a waveguide region, and the holes except on the waveguide region are filled with an air, whilst the holes on the waveguide regions are filled with a filler material having a refractive index higher than 1.

Abstract: A method for measuring the waveform of light is provided, which makes it possible to synchronize easily the phase of sampling light with the phase of target light even if the target light is ultra-high speed pulsed light and is transmitted by way of long transmission channel, and to measure the waveform of target light with sufficient time resolution in real time. The method comprises the steps of: (a) generating sampling light having a pulse width sufficiently narrower than that of the target light from the target light; a repetition frequency of the sampling light having a constant difference with respect to a repetition frequency of the target light; (b) supplying the sampling light and the target light to a nonlinear optical member to generate cross-correlated light between the sampling light and the target light; and (c) measuring waveform of the target light based on the cross-correlated light.

Abstract: A lightwave circuit, by which the degree of integration can be further improved by employing a multilayered structure of wiring, is disclosed. The disclosed photonic crystal multilayer substrate has portions, each portion having a slab-waveguide type photonic crystal structure, multilayered in the direction of the thickness of the substrate. In the photonic crystal structure, a photonic crystal layer is disposed between cladding layers; the photonic crystal layer is made of a photonic crystal having a two or three dimensional periodically modulated structure with respect to the effective refractive index in the order of optical wavelengths; and each cladding layer is made of a material whose effective refractive index differs from the effective refractive index of the photonic crystal layer.

Abstract: A semiconductor laser with a rewritable wavelength stabilizer which comprises a laser mirror made of a grating written into a photorefractive material, in which the oscillation wavelength of the laser diode is determined by the period of the grating. This allows the refractive index of the grating to be changed by illuminating the photorefractive material after cooling thereof to a temperature at which most of the doped impurities form DX centers. The grating can be erased by heating the photorefractive material to a temperature at which most DX centers are ionized, which erases the grating. Thereafter the photorefractive material is cooled again to a temperature at which most impurities become DX centers, and a new grating can be written in the photorefractive material. The wavelength of the semiconductor laser can be changed repeatedly by erasing and rewriting the grating therein.

Abstract: A method for measuring the waveform of light is provided, which makes it possible to synchronize easily the phase of sampling light with the phase of target light even if the target light is ultra-high speed pulsed light and is transmitted by way of long transmission channel, and to measure the waveform of target light with sufficient time resolution in real time. The method comprises the steps of: (a) generating sampling light having a pulse width sufficiently narrower than that of the target light from the target light; a repetition frequency of the sampling light having a constant difference with respect to a repetition frequency of the target light; (b) supplying the sampling light and the target light to a nonlinear optical member to generate cross-correlated light between the sampling light and the target light; and (c) measuring waveform of the target light based on the cross-correlated light.