Abstract: In 2D photonic crystals, cavities having a heightened Q factor are made available, wherein combining the high Q cavities with waveguides affords channel add/drop filters having high resolution. In a cavity constituted by a point defect within a 2D photonic crystal, the 2D photonic crystal is configured by an arrangement, in a two-dimensional lattice of points defined in a slab (1), of low-refractive-index substances (2) having a low refractive index relative to the slab (1) and being of identical dimension and shape. The point defect (4) contains a plurality of three or more lattice points that neighbor one another, and in these lattice points no low-refractive-index substances (2) are arranged; therein the dimension of the low-refractive-index substance (2) that should be arranged to correspond to at least one of the lattice points nearest the point defect (4) is dimensionally altered from a predetermined dimension.

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: A semiconductor material having a disordered structure consists of a semiconductor material on which epitaxial growth is possible. The semiconductor material has an energy band structure constituted by one of the indirect band structure, the direct band structure, and a combination of the indirect and the direct band structures, and consists of a plurality of semiconductor layers. The semiconductor layer is orderly arranged along its surface and disorderly arranged along its thickness direction with respect to at least one of the followings the number of atomic or molecular layers constituting the semiconductor layer, a composition of a specific molecular layer of the molecular layers, and impurity doped to the semiconductor layer.

Abstract: A device for measuring thermal conductivity of a desired sample liquid, even of a transparent or hot sample liquid, on the basis of thermal diffusion to the sample liquid from a small and thin metal disc which is heated by laser flash. The device has means for elevating the relative surface level of the sample liquid, filling a gap between the metal disc and a sample holding block to form a cylindrical liquid layer therein, and the thermal diffusion can be measured by a thermocouple connected to the metal disc.

Abstract: An apparatus for measuring thermal conductivity of a desired sample liquid, even of a transparent sample liquid, on the basis of thermal diffusion to the sample liquid from a small and thin metal disc which is heated by laser flash. The sample liquid is inserted within a small gap which is formed between the metal disc and a sample holding block, and the thermal diffusion can be measured by a thermocouple connected to the metal disc.