Abstract: An optical beam diameter reducer for reducing a beam diameter of an optical beam comprises a three-layer structure composed of a central core, a refractive index inclined layer formed outside the core which refractive index gradually decreases toward the outside in the radial direction and a cladding layer formed outside the refractive index inclined layer.

Abstract: A high power laser transmitting fluoride glass fiber of an enhanced 2.94- .mu.m laser damage threshold value is disclosed, in which either of the core with a high refractive index and the cladding with a low refractive index is formed of fluoride glass which contains fluorine (F) as a component but has it substituted with 0 to 4.1 mol % of bromine (Br), chlorine (Cl), or bromine and chlorine. The optical fiber of the present invention may have its core formed of fluoride glass and its cladding formed of fluorine-contained resin, and the core glass has a composition that 70 to 80% of fluorine (F) is substituted with 0 to 4.1 mol % of bromine (Br), or chlorine (Cl), or bromine and chlorine.

Abstract: A high-output, single fundamental transverse mode solid state laser is disclosed which uses a semiconductor laser array as an excitation light source. The solid state laser comprises: a laser element which includes a core containing an element added as a laser medium, a cladding containing no such laser medium element, and reflecting mirrors coated over the cladding surface for repeatedly reflecting incident excitation light so that it may repeatedly pass through the core; an excitation light source formed by semi-conductor laser or light emitting diode array; means for guiding the excitation light from the excitation light source to one side of the laser element for incidence thereto; and a resonator for the oscillation of the solid state laser.

Abstract: A spatial light modulator is disclosed, in which a low dark resistance single-crystal plate is used which is formed of Bi.sub.12 MO.sub.20 (where M is Si, Ge or Ti) or similar type crystal, doped with phosphorus (P) in the range of 0.03.ltoreq.P.ltoreq.0.2 in atomic percentage to provide a dark resistivity far lower than that of an undoped crystal, and a high dark resistance layer, which is of the same crystal structure as that of the single-crystal plate and lattice-matched therewith and has photoconductivity, electro-optic effect and a high dark resistivity, is provided on the light incident side of the single-crystal plate. A tapered low dark resistance single-crystal plate may be used which is formed of Bi.sub.12 MO.sub.20 (where M=Si, Ge, or Ti) or similar sillenite type crystal, doped with phosphorus (P) in the range of 0.03.ltoreq.P.ltoreq.0.

Abstract: A method and an apparatus for manufacturing a fluoride glass fiber preform are disclosed which preclude the step of pouring a glass melt into a mold from a crucible, and hence permit the fabrication of a long, homogeneous fluoride glass fiber preform free from foreign substances and air bubbles leading to scattering and which also allow ease in the fabrication of a preform having an elliptic core portion for drawing a polarized wave retaining fiber.

Abstract: A fusion splicing method for optical fibers in which optical fibers are fusion spliced in an inert gas atmosphere after water adsorbed on their surfaces is removed by decomposition in a plasma of an inert gas containing a halogen.

Abstract: A method and apparatus is disclosed which ensures highly accurate control of the core-cladding diameter, enabling the fabrication of a preform for the single mode fiber. Moreover, glass refining steps for dehydration, the removal of compound ions, the reduction of the absorption loss by transition metals, etc. and preform manufacturing steps are combined into a series of steps, and the entire manufacturing process can be mechanized and automatically controlled; therefore, the yield rate of product is high and the industrial-scale productivity is also excellent.

Abstract: A method is disclosed for manufacturing a bismuth-containing oxide single crystal, in which vapor of bismuth or alkylated bismuth and vapor of an organic compound of other metal ion components of a crystal are introduced into a heated reaction chamber to be reacted with oxygen gas, so that the desired bismuth-containing oxide single crystal is deposited on a substrate prepared in the reaction chamber. A Bi.sub.12 SiO.sub.20 single oxide crystal can be produced by the use of bismuth or alkylated bismuth and alkylated silicon or silicon alkoxide or by the use of bismuth or alkylated bismuth and alkylated germanium or germanium alkoxide. A (Y.sub.1--x Bi.sub.x).sub.3 Fe.sub.5 O.sub.12 single crystal can be poduced by the use of bismuth or alkylated bismuth yttrium alkoxide and carbonyl iron.

Abstract: In a fluoride glass optical fiber with extremely small transmission loss for infrared light having a core layer and a clad layer each consisting mainly of ZrF.sub.4 - BaF.sub.2 - LaF.sub.3 - AlF.sub.3, NaF and H.sub.f F.sub.4 are used as additives to obtain a desired refractive index difference between the core layer and the clad layer. The mixing ratio of the NaF to the H.sub.f F.sub.4 satisfies the realtions;.vertline.0.25 .DELTA.H.sub.f F.sub.4 -3.DELTA.NaF.vertline..ltoreq.5,where .DELTA.NaF is the difference between the amount (mol %) of the N.sub.a F to be added to the core layer and that to be added to the clad layer, and .DELTA.H.sub.f F.sub.4 to be added to the core layer and that to be added to the clad layer.

Abstract: A fluoride glass for infrared optical transmission fiber is purified for dehydration and deoxidation to reduce transmission loss by reacting melted fluoride glass with NF.sub.3 gas at temperature between 500.degree. C. and 800.degree. C. No scattering loss is increased by the present purification as decomposed product in the reaction does not precipitate.

Abstract: A single crystal manufacturing device, in which there are provided a crucible having a melting part for holding a molten liquid of a raw material and a nozzle part for continuously taking out a predetermined amount of the molten liquid by the action of gravity; a heater for heating the raw material to melt it in the melting part; and temperature control means for heating the nozzle part to take out the molten liquid of the raw material from the nozzle part and for providing as large a thermal gradient as possible in the solid-liquid interface between the molten liquid taken out from the nozzle part and a grown single crystal continuous to the molten liquid.The crucible can be double-structured. A guide pipe filled with fibrous material may be provided between the nozzle and the rollers of the grown single crystal.

Abstract: A fiber for optical transmission, in which a core thereof for propagating light is formed of a single crystal of an ionic substance except positive ions having no closed cell electronic structure and positive ions of strong covalency. The ionic substance is a binary system compound, a ternary or more multi-system compound, or a solid solution between a binary system compound and a ternary or more multi-system compound.

Abstract: A magnetic transfer record film employed for magneto-optically reading magnetic record patterns. The magnetic transfer record film is formed, as the principal component, of an alloy of a heavy rare earth metal and a transition metal and has an easy axis of magnetization in a direction perpendicular to the film surface and further has an alloy composition included in a range of .+-.10% at the periphery of a center alloy composition where the saturation magnetic moment becomes minimum with respect to a change of the composition within a temperature range used. The magnetic transfer record film is deposited on a transparent substrate and positioned closely to a magnetic record medium on which a magnetic record pattern to be observed is stored, so that the magnetic record pattern is transferred to the magnetic transfer record film. An optical system is provided to magneto-optically read out the transferred magnetic record pattern from the magnetic transfer record film.

Abstract: A magnetic head for reading out the state of magnetization recorded on a magnetic recording medium, in which the magnetic head comprises a substrate of insulating material, an amorphous magnetic thin film, a pair of current terminals, and a pair of voltage terminals. The amorphous magnetic thin film is deposited on the substrate so as to have a width smaller than respective unit areas of magnetic records on a magnetic recording medium to be separately read out therefrom and to have an easy axis of magnetization in a direction perpendicular to the film surface. The current terminals are formed on the substrate for flowing a current in the amorphous magnetic thin film in the lengthwise direction thereof. The voltage terminals are formed on the substrate for deriving from the amorphous magnetic thin film a voltage induced in the transverse direction thereof.

Abstract: A magneto-optical memory medium having an easy axis of magnetization perpendicular to the medium surface. The memory medium is formed by an amorphous Dy-Fe system alloy film containing 18 to 28 atom % Dy.

Abstract: A magnetic transfer record film employed for magneto-optically reading magnetic record patterns. The magnetic transfer record film is formed, as the principal component, of an alloy of a heavy rare earth metal and a transition metal and has an easy axis of magnetization in a direction perpendicular to the film surface and further has an alloy composition included in a range of .+-. 10% at the periphery of a center alloy composition where the saturation magnetic moment becomes minimum with respect to a change of the composition within a temperature range used. The magnetic transfer record film is deposited on a transparent substrate and positioned closely to a magnetic record medium on which a magnetic record pattern to be observed is stored, so that the magnetic record pattern is transferred to the magnetic transfer record film. An optical system is provided to magneto-optically read out the transferred magnetic record pattern from the magnetic transfer record film.