Abstract: Embodiments of the invention include a singlemode optical fiber having an antimony (Sb) doped core region, a suitable cladding region formed on the core region, and one or more gratings written in the optical fiber. Optical fibers manufactured according to embodiments of the invention provide faster growth of grating strength, higher thermal stability, and longer photosensitive wavelength compared to conventional Ge doped silica optical fibers. The optical fiber is fabricated for applications such as fiber grating applications where the index of the core is modulated by UV radiation. Also, the addition of Sb in the core region of the singlemode optical fiber provides higher temperature (e.g., greater than 100° C.) applications of fiber gratings and a reduced degradation of the band rejection efficiency. Also, the optical fibers are more conducive to direct and non-destructive grating writing over polymer jackets with a longer photosensitive wavelength in the UV range.

Abstract: This invention is predicated upon applicants' discovery that UV-induced gratings can be formed through polymer coatings that include conjugated double bonds and aromatic moieties. Coatings with low concentrations of aromatic-containing free-radical photoinitiators provide both reasonable curing speeds and sufficient transparency that gratings can be written through them. Moreover some of these aromatic-containing free-radical photoinitiators act synergistically with non-aromatic ketone photoinitiators. Advantageous aromatic-containing free-radical photoinitiator concentrations are in the range 0.01%-0.1% and preferably in the range 0.02% to 0.05%. Advantageous polymer coatings are acrylate-based coatings.

Abstract: Applicants have determined that much of the nonuniformity in solution doped preforms is due to nonuniformity of the soot layer caused by the high temperature necessary for complete reaction, and that MCVD fabrication using reaction temperature lowering gases such as nitrous oxide (N.sub.2 O) can produce more uniform soot layers. The conventional oxygen/reactant gas mixture presents a very small temperature window in which a uniform silica soot layer can be deposited without sintering. If the temperature in oxygen is too low, SiCl.sub.4 will not react completely and silicon oxychlorides will form. This degrades the soot layer and makes it unusable. If the temperature is too high the soot layer begins to sinter, decreasing the surface area and porosity. Adding a reaction temperature lowering gas lowers the reaction temperature and enables deposition of soot on the tube wall at a temperature substantially lower than the sintering temperature.

Abstract: In accordance with the invention, the index of refraction of a region of a glass body is selectively increased by treating the glass with hydrogen or deuterium, heating the hydrogenated glass to a temperature in excess of 500.degree. C., permitting the glass to rapidly cool below 100.degree. C. and exposing the region to UV radiation, preferably in the range 300 nm to 400 nm. The result is an increase in the refractive index of the irradiated region. Absorption is via a GODC band at 330 nm believed to result from a singlet to triplet transition. This band is about 1000 times weaker than the commonly used band at 240 nm. This process can be used to make and adjust a variety of optical waveguide devices such as photoinduced Bragg gratings and long period gratings.

Abstract: A method is provided of trimming the optical coupling ratio of an optical coupler to a prescribed value. The optical coupler is formed from a plurality of waveguides which each include a core and cladding. In accordance with the method, an irradiation energy is selected that is absorbed by portions of the waveguides located in a coupling region. A dosage of radiation is applied to the waveguide portions at least sufficient to adjust the optical coupling ratio to the prescribed value. The radiation, which may be absorbed by the cladding and/or the core of the waveguides, causes a change in the refractive index difference between the core and cladding of the waveguides. This change in the refractive index difference will result in a change in the optical coupling ratio of the device.

Abstract: The method of making an optical fiber refractive index grating comprises writing the grating through the fiber coating. The method involves providing optical fiber of significantly higher photosensitivity than conventional fiber, such that the grating can be written before unacceptable darkening of the coating occurs. Such fiber is H.sub.2 and/or D.sub.2 -loaded silica-based fiber having a Ge-doped core, the fiber selected to have a germanium-oxygen deficiency center content that provides the fiber with a photosensitivity that is at least twice as large as that of an otherwise identical, conventionally prepared, optical fiber. The fiber typically is drawn from a preform, at least a portion of which was exposed to a reducing atmosphere at an elevated temperature.

Abstract: An optical fiber formed from a glass preform substantially free of OH impurities is disclosed. The optical fiber is made to be free of OH impurities by a method having the steps of introducing a moving stream of vapor mixture including at least one compound glass-forming precursor together with an oxidizing medium into a tube, while generating a hydrogen-fee isothermal plasma on an outer surface of the tube to react the mixture and produce a glassy deposit on an inner surface of the tube. The glass preform is drawn to produce the optical fiber.