Abstract: A matrix switch of an optical waveguide type which has low transmission loss variations and includes uniform grooves with a deep vertical cross section is provided. A switching part for selecting between a light path extending from an input port of a first set of optical waveguides 111-11m to an output port of the first set of optical waveguides 111-11m and a light path extending from an input port of the first set of optical waveguides 111-11m to an output port of a second set of optical waveguides 121-12n is arranged for insertion into a switching groove arranged at each of the intersections of the first set of optical waveguides 111-11m and the second set of optical waveguides 121-12n. Each of the switching grooves is arranged on an imaginary straight line connecting intersections of the first set of optical waveguides 111-11m and the second set of optical waveguides 121-12n.

Abstract: An optical multiplexing/demultiplexing apparatus in which a plurality of optical multiplexing/demultiplexing units operating in different wavelength bands are connected hierarchically. Each of the plurality of optical multiplexing/demultiplexing units includes an input waveguide for receiving wavelength multiplexed optical waves, a filter for separating the wavelength multiplexed optical wave from the input waveguide into a first optical wave in a corresponding operating wavelength band and a second optical wave in the other wavelength bands. Each of the multiplexing/demultiplexing units also includes an AWG optical multiplexer/demultiplexer for separating the first optical wave from the filter into individual optical waves each of a single wavelength, and a branch waveguide for directing the second optical waves from the filter to an input waveguide of a succeeding optical multiplexing/demultiplexing unit.

Abstract: A matrix switch of an optical waveguide type which has low transmission loss variations and includes uniform grooves with a deep vertical cross section is provided. A switching part for selecting between a light path extending from an input port of a first set of optical waveguides 111-11m to an output port of the first set of optical waveguides 111-11m and a light path extending from an input port of the first set of optical waveguides 111-11m to an output port of a second set of optical waveguides 121-12n is arranged for insertion into a switching groove arranged at each of the intersections of the first set of optical waveguides 111-11m and the second set of optical waveguides 121-12n. Each of the switching grooves is arranged on an imaginary straight line connecting intersections of the first set of optical waveguides 111-11m and the second set of optical waveguides 121-12n.

Abstract: An optical multiplexing/demultiplexing apparatus in which a plurality of optical multiplexing/demultiplexing units which are different from one another in operating wavelength band are connected hierarchically. Each of the optical multiplexing/demultiplexing units comprises an input waveguide for receiving a wavelength multiplexed optical waves, a filter for separating the wavelength multiplexed optical wave from the input waveguide into a first optical wave in the corresponding operating wavelength band and a second optical wave in the other wavelength bands, an AWG optical multiplexer/demultiplexer for separating the first optical wave from the filter into individual optical waves each of a single wavelength, and a branch waveguide for directing the second optical waves from the filter to the input waveguide of a succeeding optical multiplexing/demultiplexing unit.

Abstract: An optical multiplexing/demultiplexing apparatus in which a plurality of optical multiplexing/demultiplexing units which are different from one another in operating wavelength band are connected hierarchically. Each of the optical multiplexing/demultiplexing units comprises an input waveguide for receiving a wavelength multiplexed optical waves, a filter for separating the wavelength multiplexed optical wave from the input waveguide into a first optical wave in the corresponding operating wavelength band and a second optical wave in the other wavelength bands, an AWG optical multiplexer/demultiplexer for separating the first optical wave from the filter into individual optical waves each of a single wavelength, and a branch waveguide for directing the second optical waves from the filter to the input waveguide of a succeeding optical multiplexing/demultiplexing unit.

Abstract: A plate plastics optical waveguide includes a core portion composed of a polymer containing a deuterium atom or a halogen atom, and a clad portion which surrounds the core portion and is composed of a polymer having a refractive index lower than that of the core portion. A plastics optical waveguide having a core portion comprising a deuterated or halogenated polyacrylate or polysiloxane shows an optical loss of 0.1 dB/cm or less for light having a wavelength of 1.3 .mu.m.

Abstract: Halides of Si and Ti, B, P, or Ge and oxygen or steam are introduced into a reaction vessel and heated in a vapor phase to form fine glass particles by oxidation or hydrolysis. The fine glass particles are deposited on a substrate. The deposited fine glass particles are heated and vitrified into a transparent glass layer, which is etched to form a core having a desired pattern by a reactive sputter etching process using Freon gas. The core is coated by a clad. In a waveguide thus formed, the cross sectional configuration and dimensions of the core layer and the refractive index difference are precisely controlled. The waveguide is manufactured with good reproducibility. The fabrication method is suitable for mass production of waveguides. An expansion coefficient transient layer is provided between the core layer and the substrate to prevent a crack in the waveguide.

Abstract: Two gaseous raw glass materials containing dopants to provide different refractive indices and borne by an argon carrier are jetted from the central or inner and first concentric nozzles 11, 12 of a five tip burner 1; an argon shield is supplied through the second concentric nozzle 13, and hydrogen and oxygen are supplied through the third and fourth concentric nozzles 14, 15, respectively. Soot-like glass particles 4 are formed by flame hydrolysis and deposited on the lower end of a start rod 3 which is gradually rotated and withdrawn to thus grow a cylindrical preform 2. The intermixing of the particles formed from the two glass materials produces a preform having a substantially parabolic radial index of refraction distribution, which characteristic is retained in an optical communication fiber formed by sintering and drawing the preform.

Abstract: A refractory starting member is rotated and, at the same time, moved along the axis of rotation. A glass raw material for the formation of the core of a porous preform and consequently an optical fiber preform is introduced into a high temperature portion near the tip of a high temperature burner from a nozzle for the core disposed in alignment with the center of rotation of one end face of the starting member. The glass raw material blown out from the nozzle for the core are caused by the flames of the high temperature burner to react to produce glass fine particles, which are deposited on abovesaid end face of the starting member at the central portion thereof in its axial direction to form a porous core. At least one nozzle for spraying a glass raw material for the formation of the cladding of the optical fiber preform is disposed opposite to the end face of the starting member but a little deviated from the axis of rotation thereof, or disposed opposite to the peripheral surface of the porous core.

Abstract: A method for manufacturing a glass core rod and a cladding layer clothing the glass core rod applied successively or continuously by using a carbon dioxide gas laser. A refractory mandrel is heated by means of carbon dioxide gas laser irradiation and a mixed gas of oxygen and pure silicon tetrachloride vapor and a dopant compound vapor is ejected to the refractory mandrel so as to deposit silicon oxide and oxide of the dopant compound on the mandrel and to form a glass core by fusing it. Further heating is applied by irradiation by the carbon dioxide laser beam on the glass core and a mixed gas oxygen and pure silicon tetrachloride vapor and a dopant compound vapor or of oxygen gas and pure silicon tetrachloride vapor to deposit silicon oxide and oxide of the dopant compound or silicon oxide on the glass core to form a cladding layer of fused silica or fused silica containing the dopant.