Abstract: The present invention provides a method for manufacturing an optical fiber base material and an optical fiber base material, the method including: arranging a rod containing SiO2 family glass for core, in a container; pouring a SiO2 glass raw material solution for cladding layer and a hardener into the container, the glass raw material solution containing a hardening resin; solidifying the glass raw material solution through a self-hardening reaction; and then drying the solidified material and heating the solidified material in chlorine gas, to manufacture an optical fiber base material in which a SiO2 cladding layer is formed in an outer periphery of the rod containing SiO2 family glass for core.

Abstract: An optical connector connects: N (N is an integer of 3 to 14) single-mode fibers each including one core with a high refractive index in a cladding material with a low refractive index; to multi-core fiber including N cores with high refractive indexes in a cladding material with low refractive index such that the cores of the single-mode fibers are respectively optically coupled to cores of the multi-core fiber. The optical connector includes: quartz glass cylinder having a first end face to be in contact with the multi-core fiber and a second end face to be in contact with single-mode fibers; N glass fibers that are arranged in the quartz glass cylinder to extend from the first to second end face, the N glass fibers each including: a circular rod with high refractive index that has a constant outer diameter; and a low refractive index material that surrounds an outer periphery of the circular rod and has a constant thickness.

Abstract: The present invention provides a method for manufacturing an optical fiber base material and an optical fiber base material, the method including: arranging a rod containing SiO2 family glass for core, in a container; pouring a SiO2 glass raw material solution for cladding layer and a hardener into the container, the glass raw material solution containing a hardening resin; solidifying the glass raw material solution through a self-hardening reaction; and then drying the solidified material and heating the solidified material in chlorine gas, to manufacture an optical fiber base material in which a SiO2 cladding layer is formed in an outer periphery of the rod containing SiO2 family glass for core.

Abstract: Provided is an optical connector that can optically couple a multi-core fiber and single-mode fibers with a high efficiency. The optical connector connects: N (N is an integer of 3 to 14) single-mode fibers each including one core with a high refractive index, in a cladding material with a low refractive index; to a multi-core fiber including N cores with high refractive indexes in a cladding material with a low refractive index such that the cores of the single-mode fibers are respectively optically coupled to the cores of the multi-core fiber.

Abstract: In a polymer waveguide comprising a cladding layer with a low refractive index and a core layer with a high refractive index of a substantially rectangular section covered with the cladding layer, the core layer and a side cladding layer constituting the cladding layer in its portion located on both sides of the core layer are formed of a material comprising a branched polysilane compound containing a silicone compound. By virtue of this constitution, the polymer waveguide has a low loss and causes no significant change in optical characteristics upon a change in ambient temperature.

Abstract: A silicone compound, either alone or in combination with a photoacid generator, is added to a branched polysilane compound. According to this constitution, highly reliable polymer material and polymer film can be realized which have excellent stability of refractive index against heat and high transparency and, when the photoacid generator is contained, can cause a change in refractive index upon exposure to ultraviolet light with high sensitivity and high resolution.

Abstract: A silicone compound, either alone or in combination with a photoacid generator, is added to a branched polysilane compound. According to this constitution, highly reliable polymer material and polymer film can be realized which have excellent stability of refractive index against heat and high transparency and, when the photoacid generator is contained, can cause a change in refractive index upon exposure to ultraviolet light with high sensitivity and high resolution.

Abstract: In a polymer waveguide comprising a cladding layer with a low refractive index and a core layer with a high refractive index of a substantially rectangular section covered with the cladding layer, the core layer and a side cladding layer constituting the cladding layer in its portion located on both sides of the core layer are formed of a material comprising a branched polysilane compound containing a silicone compound. By virtue of this constitution, the polymer waveguide has a low loss and causes no significant change in optical characteristics upon a change in ambient temperature.

Abstract: A laser device dices a substrate by generating a continuous wave-oscillation laser beam 3 that is converged by a lens 4 and focused at a predetermined focus O between the surface of the substrate 1 and a tip of a nozzle of a guide 5. Then, the focus is expanded to result in a laser beam 3a having a beam spot diameter of S at the surface of the substrate 1. A flow of assist gas G.sub.0, G.sub.1, G.sub.2 having a predetermined constant pressure is supplied from a gas intake 6 surrounding the laser beam 3. As the laser beam 3a is defocused, the beam spot diameter S is expanded and its energy distribution is moderated. The gas is blown onto the substrate 1 at constant pressure in order to suppress generation of strains due to thermal deformation.

Abstract: A rare earth element-doped multiple-core optical fiber 31 has a bundle of cores 32-1.about.32-7 co-doped with Er and Al, primary cladding layers 33 covering each core, and an outer cladding layer 34 covering all cores 32-1.about.32-7, wherein one core 32-1 being positioned substantially on a central axis of the outer cladding layer and surrounded by other six cores 32-2.about.32-7. A core diameter Dc of the center core 32-1 is smaller than a core diameter Do of each peripheral core 32-2.about.32-7. The power of both signal light (1.53 .mu.m.about.1.57 .mu.m wavelength bands) and pumping light (0.98 .mu.m or 1.48 .mu.m band) propagating through the center core 32-1 becomes lower and the power propagating through each core 32-1.about.32-7 is equalized, and the flatter characteristics of gain to wavelength are obtained.

Abstract: A rare earth element-doped multiple-core optical fiber has an outer cladding layer and a plurality of cores each covered with a primary cladding layer. The cores are positioned substantially on a central axis of the outer cladding layer and separated with a predetermined spacing S from each other by the primary cladding layer. The outer cladding layers are made of SiO.sub.2, or SiO.sub.2 added with a dopant like F, Ge, etc. The primary cladding layer is made of SiO.sub.2 doped with Er, or SiO.sub.2 doped with Er and F together and formed to have a predetermined thickness of 1.0 .mu.m.about.1.5 .mu.m to form the predetermined spacing S. The Soot glass rods for cores and primary cladding layers are immersed in an Er-compound solution, then picked up, dried and consolidated to form Er--Al co-doped SiO.sub.2 --GeO.sub.2 transparent glass rods.

Abstract: An Er-doped multiple-core optical fiber amplifier has an Er-doped multiple-core optical fiber. A signal light of 1.5 .mu.m wavelength band is input through an optical isolator at front stage, and excitation lights of 0.98 .mu.m or 1.48 .mu.m wavelength emitted from excitation light sources are injected through a WDM coupler at front stage and a WDM coupler at rear stage, respectively. An amplified signal light is output through optical isolator at rear stage. A length L.sub.M of the Er-doped multiple-core optical fiber is set to obtain a substantially maximum saturated output power of the amplified signal light.

Abstract: A rare earth element-doped multiple-core optical fiber 31 has a bundle of cores 32-1.about.32-7 co-doped with Er and Al, primary cladding layers 33 covering each core, and an outer cladding layer 34 covering all cores 32-1.about.32-7, wherein one core 32-1 being positioned substantially on a central axis of the outer cladding layer and surrounded by other six cores 32-2.about.32-7. A core diameter Dc of the center core 32-1 is smaller than a core diameter Do of each peripheral core 32-2.about.32-7. The power of both signal light (1.53 .mu.m.about.1.57 .mu.m wavelength bands) and pumping light (0.98 .mu.m or 1.48 .mu.m band) propagating through the center core 32-1 becomes lower and the power propagating through each core 32-1.about.32-7 is equalized, and the flatter characteristics of gain to wavelength are obtained.

Abstract: At least three elementary optical fibers are covered with a jacket layer. Each of the elementary optical fibers has a core of a first refractive index doped with at least one rare earth element and Al, and a cladding layer of a second refractive index lower than the first refractive index for covering the core. A value of (1+2t/Dw) is ranged to be 1.1 to 2.5, where t is a thickness of the cladding layer, and Dw is an outer diameter of the core, and a doping amount of Al is at least 1 weight %. The at least three elementary optical fibers are inserted into a jacket tube, and the elementary optical fibers and the jacket tube are heated to be welded at contact surfaces thereof by vacuum-drawing air from interstices of the elementary optical fibers and the jacket tube. Thus, a preform is obtained, and the preform is heated to be drawn. Consequently, a rare earth element-doped multiple-core optical fiber is fabricated.

Abstract: A polymer core optical wave-guide which comprises a substrate, a buffer layer formed on the surface of the substrate made of a SiO.sub.x N.sub.y H.sub.z film of desirable thickness having a refractive index of n.sub.b, an approximately rectangle-shaped core formed on the buffer layer made of a polymer material having a refractive index of n.sub.w (n.sub.w >n.sub.b), a cladding layer covering the surface of the core having a refractive index of n.sub.c (n.sub.c <n.sub.w).

Abstract: An optical waveguide with a specific refractive index difference .DELTA..sub.1 has a constitution in which a core with a high refractive index and having a rectangular section is built in a cladding layer with a low refractive index formed on a substrate. A pig tail optical fiber, formed by a first fiber serially connected to a second fiber, each having a different specific refractive index difference, is connected to an input terminal of the optical waveguide. The second fiber has a specific refractive index difference .DELTA..sub.2 (<.DELTA..sub.1) and is connected to a terminal of the first fiber which has a specific refractive index difference nearly equal to .DELTA..sub.1. A diffusion region in the neighborhood of the connection is formed by diffusing a dopant for refractive index control in the core of the second fiber by heat addition. Due to the diffusion region, the diameters of the first fiber and the second fiber are adjusted so as to be nearly equal.

Abstract: A core waveguide having a substantially rectangular cross section, with the width thereof greater than the thickness thereof, is provided in a cladding formed on a substrate, and a rare earth element-doped layer is provided in the core waveguide along the waveguiding direction of the waveguide. With the width of the core waveguide set greater than the thickness of the core waveguide, good optical confinement in the width direction of the waveguide is obtained, which enables light to be absorbed by the rare earth element-doped layer efficiently and concentratedly. It is thereby possible to achieve a marked improvement in the excitation efficiency of excitation power. Thus, an enhanced excitation efficiency is achieved with less addition of a rare earth element, and a high-gain optical amplification waveguide free of concentration extinction is provided.

Abstract: An optical star coupler comprises an optical fiber bundle consisting of a plurality of optical fibers. The central portion of the optical fiber bundle is twisted, fused and pulled under heating so as to form a tapered region, and the outer peripheral portion of the tapered region is coated with a dielectric substance.

Abstract: An optical receiving method utilizing polarization diversity is disclosed in which first and second reference lightwaves having different frequencies and having polarization planes substantially perpendicular to each other, are combined with a signal lightwave to form a combined lightwave. The combined lightwave is subjected to heterodyne detection to obtain a detection signal and the detection signal is separated into first and second intermediate-frequency signals having different carrier frequencies. The first and second intermediate-frequency signals are converted into first and second baseband signals, respectively, and the first and second baseband signals are added to obtain an output signal.

Abstract: An optical waveguide star coupler includes a light propagating core provided on a substrate. An exciting light and a signal light are supplied to the light propagating core. The light propagating core includes a plurality of Y-branching waveguides connected one after another to provide a multi-stage waveguide structure. A signal light inputted in the core is combined during the propagation through the core with the exciting light so that the signal light is amplified.