Abstract: A porous silica body with a density of 0.1 g/cm.sup.3 to 0.5 g/cm.sup.3 and a density variation of less than 30% is subjected to a first heat-treatment in an ammonia-containing atmosphere, a second heat-sintering in non-oxidizing atmosphere, and further heat-treatment at a temperature in the range of 1400.degree. C. to 2000.degree. C. under an increased pressure of 500 kg/cm.sup.2 or more in a non-oxidizing atmosphere.
Abstract: A glass body for optical fiber containing GeO.sub.2 --SiO.sub.2 glass in a core portion thereof, in which the GeO.sub.2 --SiO.sub.2 glass has an absorbance at 5.16 eV of at least 1/mm but not higher than 2.5/mm or in which concentration of Ge.sup.2+ contained in the GeO.sub.2 --SiO.sub.2 glass substantially lies within the range of 1.1.times.10.sup.-9 to 2.8.times.10.sup.-9 mol/mm.sup.3 as calculated by the following general equation:A=.epsilon..sub.5.16ev .multidot.C.sub.(Ge2+) .multidot.1wherein A is absorbance which is expressed by A=-log T (T being transmittance) and normalized per 1 mm of optical path length, C.sub.(Ge2+) is Ge.sup.2+ concentration, .epsilon..sub.5.16ev is absorption coefficient (1/mol/cm), and 1 is optical path length.
Abstract: A process for producing fluoride glass, including the steps of: introducing a raw material for fluoride glass into a heating vessel; and heating the raw material in the heating vessel, while causing the heating vessel to have a negative internal pressure and introducing an inert gas into the heating vessel, thereby to melt the raw material under heating.
Abstract: The invention relates to the production of high purity fused silica glass which is highly resistant to 248 nm excimer laser-induced optical damage. In particular, this invention relates to a fused silica optical member or blank.
Type:
Grant
Filed:
December 10, 1996
Date of Patent:
April 7, 1998
Assignee:
Corning Incorporated
Inventors:
Roger J. Araujo, Nicholas F. Borrelli, Christine L. Hoaglin, Charlene Smith
Abstract: An induction-heated furnace, suitable for heat treatment of synthetic silica bodies, under conditions of high purity, includes a tubular susceptor (1) disposed with its axis vertical and an induction coil (3) for raising the temperature of the susceptor. The susceptor is made from graphite and/or silicon carbide, and is enclosed within a vacuum envelope (2) made from vitreous silica or fused quartz, the envelope being surrounded by the induction coil which is liquid-cooled. The design is such that the vacuum envelope (2) operates at temperatures below those at which either devitrification or sagging of the envelope might occur even when the tubular susceptor (1) is heated to a temperature of 1700.degree. C. Thus sintering of a porous synthetic silica body (9) can be carried out under atmospheric or reduced pressure, the furnace including a shaft (7) adapted to support the body to be heated and capable of rotation about and movement along said vertical axis of the tubular susceptor (1).
Type:
Grant
Filed:
November 10, 1994
Date of Patent:
February 3, 1998
Assignee:
TSL Group PLC
Inventors:
Robert Nicholson, Bernard Phillipe Robert Poullain, Ian George Sayce
Abstract: During the gradual build-up of porous quartz glass by the combustion of a hydrolysis gas mixture and preferably for a certain period of time thereafter, a drying gas mixture is conducted under positive pressure through the porous tubular deposit from the inside to the outside as it is being built-up. This is accomplished by depositing the quartz on a tubular substrate in which a drying gas is introduced at positive pressure.
Abstract: A method and apparatus are provided for drawing a self-aligned core fiber free of surface contamination and inserting the core fiber into a cladding material to make an optical fiber preform. Single or multi-mode optical fibers having high quality core-clad interfaces can be directly drawn from the preforms described herein.
Abstract: In accordance with the invention, the index of refraction of a glassy material is increased by treating the material with hydrogen and applying heat. Specifically, the glass is exposed to hydrogen or deuterium at pressure in the range 14-11,000 p.s.i. and a temperature in the range 21.degree.-150.degree. C. for a time sufficient for the hydrogen to diffuse into the glass. The glass is then subjected to heat in excess of about 500.degree. C., as by application of a flame or infrared radiation. The duration of heating can be less than a second. The result is a substantial and long-lived increase in the normalized refractive index. For example, flame heating of H.sub.2 loaded commercial GeO.sub.2 doped optical fibers (AT&T Accutether single mode fiber) has produced normalized index changes .increment.n/n of 4.times.10.sup.-3. This process can be used to make and adjust a variety of optical waveguide devices.
Type:
Grant
Filed:
December 14, 1994
Date of Patent:
March 19, 1996
Assignee:
AT&T Corp.
Inventors:
Robert M. Atkins, Paul J. Lemaire, Victor Mizrahi, Kenneth L. Walker
Abstract: In accordance with the invention, the index of refraction of a region of a glass body is selectively increased by treating the material with hydrogen and then simultaneously applying heat and actinic radiation to the region. Preferably the body is heated to a temperature in excess of 150.degree. C. and the heat and radiation are simultaneously applied. The result is a substantial and long-lived increase in excess of 5.times.10.sup.-5 in the refractive index of the irradiated region. This process can be used to make and adjust a variety of optical waveguide devices such as photoinduced Bragg gratings.
Type:
Grant
Filed:
September 13, 1994
Date of Patent:
December 26, 1995
Assignee:
AT&T Corp.
Inventors:
Paul J. Lemaire, William A. Reed, Ashish M. Vengsarkar
Abstract: A new method for preparing low loss multimode and monomode glass optical fibers which avoids casting or pouring the core and clad melts is disclosed. The new technique is based on a reactive-gas-transport approach which avoids contamination from absorbing impurities and scattering centers by reacting the glass melt with reactive gases which remove impurities and increase the refractive index of the fiber.