Abstract: In a single mode optical waveguide having a substrate, a cladding layer formed on the substrate, a core portion embedded in the cladding layer, and an elongated member for applying a stress to the core portion or a stress relief groove for relieving a stress from the core portion in the cladding layer along the core portion. The position, shape and material of the elongated member or the groove are determined in such a way that stress-induced birefringence produced in the core portion in accordance with a difference in thermal expansion coefficient between the substrate and the single mode optical waveguide is a desired value.

Abstract: A hybrid optical integrated circuit having a high-silica glass optical waveguide formed on a silicon substrate, an optical fiber and an optical device coupled optically to the optical waveguide, and an optical fiber guide and an optical device guide on the substrate for aligning the optical fiber and the optical device at predetermining positions, respectively, relative to the optical waveguide. Islands carrying electrical conductors are disposed on the substrate. A first electrical conductor film is formed on the substrate. Second electrical conductor films are formed on the top surfaces of the optical waveguide, the optical fiber guide, the optical device guide and the islands and are electrically isolated from the first electrical conductor film. An electrical conductor member is provided to feed electric power from the first and second electric conductor films to the optical device which needs the power supply.

Abstract: A method for fabricating a hybrid optical integrated circuit having a high-silica glass optical waveguide formed on a silicon substrate, an optical fiber and an optical device coupled optically to the optical waveguide, and an optical fiber guide and an optical device guide on the substrate for aligning the optical fiber and the optical device at predetermined positions, respectively, relative to the optical waveguide. Islands carrying electrical conductors are disposed on the substrate. A first electrical conductor film is formed on the substrate. Second electrical conductor films are formed on the top surfaces of the optical waveguide, the optical fiber guide, the optical device guide and the islands and are electrically isolated from the first electrical conductor film. An electrical conductor member is provided to feed electric power from the first and second electric conductor films to the optical device which needs the power supply.

Abstract: An infrared ray-transmitting glass composition for optical fibers consisting essentially of 28 mol % to 38 mol % of BaF.sub.2, 2 mol % to 7 mol % of GdF.sub.3 and 58 mol % to 69 mol % of ZrF.sub.4, and optical fibers comprising said glass composition.

Abstract: Glass material for infrared ray-transmitting optical fibers comprises a three-component material made of a 28 mol % to 38 mol % BaF.sub.2 -2 mol % to 7 mol % GdF.sub.3 -58 mol % to 69 mol % ZrF.sub.4 -based composition. The glass material is cast in a metal mold with a hollow section which is preheated to a temperature of at least 100.degree. C. but below the glass deformation temperature and annealing the melt in the metal mold to form a glass rod. The glass rod forming step includes heating the melt in the temperature range of between about 200.degree. C. and less than the glass deformation temperature and cooling the melt. The glass rod is removed from the metal mold and optically polished at the ends and sides and is then drawn into a fiber while applying tension to the tip of the glass rod while the glass rod is being heated. The glass rod is drawn into a glass fiber while maintaining the temperature at the end portion of the glass rod constant.

Abstract: Glass for optical fibers is made of material of a binary system containing a fluoride selected from BaF.sub.2, SrF.sub.2 CaF.sub.2 and PbF.sub.2 and another fluoride selected from AlF.sub.3 and ZrF.sub.4.