Abstract: A glass preform for an optical fiber is effectively drawn by connecting dummy rods to both ends of the glass preform and connecting the dummy rods to fitting members.

Abstract: The present invention relates to a method for precisely elongating a glass preform of an optical fiber body having a desired outer diameter. In this method, a predetermined part of the glass preform is elongated as tensile stress is applied to one end of the glass preform while a predetermined part of the glass preform is heated and softened successively from one end toward the other end of the glass preform. In this elongating operation, while the outer diameter of the softening portion of the glass preform is measured, the tensile stress is adjusted such that the outer diameter of the softening portion coincides with a preset value of the control outer diameter. In particular, this method is characterized in that the preset value of the control outer diameter is changed at least during a predetermined period until termination of elongation or during a predetermined period from the start of elongation.

Abstract: In order to provide an improved process for the production of a glass preform for an optical fiber which includes substantially no bubble formation therein and also has a substantially uniform shape, the present invention provides a process for the production of a glass preform which is at least partially formed from silica. In particular, a body is formed on a rod by depositing fine glass particles thereon, preferably by the vapor phase reactions, and heating the body to vitrify under a reduced atmosphere or a vacuumed atmosphere so that the glass preform is produced.

Abstract: A method of manufacturing an optical fiber in which the deviation of a cutoff wavelength from a design value can be minimized. It is found that, upon diameter reduction of a porous core glass body by heat treatment, when the diameter reduction ratio is set to a value larger than 0.90, a "spike" in the refractive index distribution curve of a core can be prevented, and the deviation of the cutoff wavelength from the design value can be minimized. Therefore, there is provided a method comprising the first step of depositing fine SiO.sub.2 particles and fine GeO.sub.2 particles, which are produced by a core formation burner, to grow a porous core glass body from a distal end of a rotating starting rod in an axial direction, the second step of performing diameter reduction by heating the grown porous core glass body by heating means while growing the porous core glass body, and the third step of depositing fine SiO.sub.

Abstract: A glass preform for an optical fiber is effectively drawn by connecting dummy rods to both ends of the glass preform and connecting the dummy rods to fitting members.

Abstract: An apparatus for vitrifying a soot preform from which an optical fiber is produced by drawing, is composed of a main vacuum chamber 20 in which a muffle tube 70 for vitrifying the soot preform PF is located, and an auxiliary vacuum chamber 30 mounted on the main vacuum chamber 20 and communicated therewith through a passage, and a gate valve 60 for opening and closing the passage. The muffle tube 70 has a inner surface covered with silicon carbide layer 70a.

Abstract: A thin glass film is formed on a substrate using a sol-gel method by applying to the substrate a hydrolyzable solution which contains a metal alkoxide, water, an alcohol and an acid, contacting the applied solution with an atmosphere containing ammonia and an alcohol to polycondensate the metal alkoxide, and heating to form the thin glass film.

Abstract: A glass preform for an optical fiber containing a dopant in a core portion at a high concentration is produced by providing a glass tube, forming a coating film of a sol-gel solution containing a dopant compound on an inner wall of the glass tube, vitrifying and collapsing the glass tube having the coating of the sol-gel solution to obtain a glass rod.

Abstract: A quartz optical waveguide comprising a substrate, a ridge-form core part formed on said substrate and a part which surrounds said core part and has a lower refractive index than that of said core part, wherein a refractive index changes continuously at an interface between said core part and said part having the lower refractive index, which has a decreased transmission loss and a connection loss when connected with an optical fiber.

Abstract: An optical switch with improved stability which has a flat waveguide including at least two optical waveguides which are made of a glass containing silica and arranged closely each other, at least a core part of each of the optical waveguides consisting of an amorphous material which is prepared by a sol-gel method and contains organic molecules doped and orientated in a direction of electrostatic field by the application of an electrostatic field, and means for changing an optical path through change of a refractive index of the core part by applying an external force to the core part, which means is provided near the core part.

Abstract: There is disclosed an optical component capable of amolifying function by itself and a method of producing thereof. The component includes a light amplifying portion therein and the light amplifying portion includes active elements which serves the light amplification. In the producing method, the amplifying portion is, for example, formed by utilizing sol-gel method to introduce the active elements.

Abstract: A quartz optical waveguide comprising a support, a quartz glass core part formed on said support and a part which surrounds said core part and has a lower refractive index than that of said core part, wherein said core part and/or a part of said lower refractive index part through which light is guided have a functional material waveguide film containing a functional material, which has a function such as laser amplification or a linear optical effect.

Abstract: A quartz optical waveguide comprising a substrate, a ridge-form core part formed on said substrate and a part which surrounds said core part and has a lower refractive index than that of said core part, wherein a refractive index changes continuously at an interface between said core part and said part having the lower refractive index, which has a decreased transmission loss and a connection loss when connected with an optical fiber.

Abstract: There is disclosed an optical component capable of amolifying function by itself and a method of producing thereof. The component includes a light amplifying portion therein and the light amplifying portion includes active elements which serves the light amplification. In the producing method, the amplifying portion is, for example, formed by utilizing sol-gel method to introduce the active elements.