Abstract: A method for producing an optical fiber preform comprising jetting a glass raw material mixture containing at least one phosphorous compound and a fuel gas through a burner, hydrolyzing the raw materials in the flame to form fine glass particles, depositing the fine glass particles to form a porous glass preform, and then sintering the porous glass preform in a stream of an inert gas with removing phosphorus liberated from the preform to produce a transparent optical fiber preform, from which transparent optical fiber preform, an optical fiber having low attenuation at a wavelength of about 1.52 micrometer is produced.

Abstract: An optical fiber comprising a core essentially made of quartz and a cladding made of fluorine added quartz is fabricated with good productivity from a glass preform produced by a method comprising maintaining a hollow cylindrical porous glass preform in a first high temperature atmosphere comprising at least one fluorine-containing compound with jetting a cooling gas through the central hollow part of the porous glass preform to grade the amount of fluorine to be added in the radial direction of the porous glass preform and then sintering the porous glass preform in a second high temperature atmosphere kept at a temperature higher than the first high temperature atmosphere to make it transparent.

Abstract: A method of manufacturing an O-ring type optical waveguide wherein a layer of fused silica is formed on the smooth cylindrical surface of an elongated member of fused silica and thereafter a thin layer of doped fused silica having an index of refraction greater than that of said fused silica is formed over said layer of fused silica. A second layer of fused silica is then formed over the layer of doped fused silica and the composite structure is heated to its drawing temperatures and drawn to reduce the cross sectioned area thereof to form an optical waveguide having a cylindrical layer of higher refractive index interposed between a core and an outer cylindrical layer of lesser refractive index.

Abstract: An optical fiber cable of a structure comprising optical fibers, cushion layers supporting the fibers by way of low friction layers and a strengthening member provided lengthwise along the cable, wherein concentrated tension and compression applied to the optical fibers due to the external bending force can be dispersed through the cushion and low friction layers and the tension applied to the entire cable can be received by the strengthening member.

Abstract: An O-type optical waveguide comprising a rod of fused silica having formed thereon a layer of doped fused silica having an index of refraction which is greater than that of the rod, and an outside layer of fused silica over the layer of doped fused silica. The surfaces between of doped silica, having the higher refractive index, and the low adjacent layers between which it lies are extremely smooth and clean or free from foreign particles thereby preventing scattering loss due to the inclusion of foreign particles.