Abstract: An optical device includes a photonic crystal main unit, an optical waveguide, an active region, an active substance, and a light source. The active region is formed in the optical waveguide and accommodates the liquid active substance formed with a four-level light-emitting material. For example, an accommodating unit formed in the active region is provided, and the active substance is accommodated in the accommodating unit. The active substance can be formed with an aqueous solution of a dye such as rhodamine, for example.

Abstract: A substrate for mounting an optical component is provided with a base member having a semiconductor device mounting portion including a higher located first area to have optical semiconductor devices mounted on its outer surface and a second area which is stepped down from the first area so as to be located lower than the first area; an insulation layer provided in the second area of the base member so as to have substantially the same height as the first area and having a smaller dielectric loss tangent than the base member; and driving electrode patterns provided on the insulation layer for driving the optical semiconductor devices. Further, an optical module is constructed by mounting optical semiconductor devices on the base member and providing an optical waveguide so as to be optically coupled with the optical semiconductor devices.

Abstract: Plural layers of metallic particle layers in which metallic particles having morphological anisotropy are dispersed and dielectric layers are alternately stacked on at least one pricipal surface of a substrate having transparency to form a polarizing layer. The content of the group 0 elements in the polarizing layer is kept not higher than 1.5.times.10.sup.20 molecules/cm.sup.3.

Abstract: A metal such as Au and a dielectric such as borosilicate glass are simultaneously sputtered to form a film on a glass substrate. Next, this film is heated to grow metal particulates. Next, the substrate is drawn on heating to give an anisotropy to the metal particulates and produce a polarizer. The metal particulates are spheroidal and are dispersed almost homogeneously in the dielectric.