Chevron Research Company

Donald C Schmadel

Jack E Goodman

William H Culver

An apparatus and process are described which can measure the strength of an evanescent field at the surface of an optical fiber. Light is injected into an end of the optical fiber while the portion of the fiber to be tested is contacted with a material having a higher index of refraction than the optical fiber. The amount of light lost, i.e., coupled out of the fiber, is a function of the evanescent field strength at the cladding surface of the optical fiber. This loss can be correlated with optical fibers which have thicker and thinner claddings to determine the thickness of the cladding and/or the extent of removal of the cladding by, for example, etching.

Process and apparatus for measuring an evanescent field in an optical

A frequency shifted cavity apparatus for electromagnetic radiation.

Frequency shifted cavity for electromagnetic radiation

A tuned optical fiber grating and a tuning process is disclosed. The gratings on the optical fiber ar tuned so that the reflectance of the grating can occur at a specific wavelength. The process involves encasing that portion of the fiber containing the grating while shining light of the wavelength of desired reflectance through the fiber and stretching the grating until reflectance occurs. Thereafter, the tuned grating is sealed within a tube formed around the tuned grating.

Process of tuning a grated optical fiber and the tuned optical fiber

A ruggedized grated optical fiber is described. The gratings in the fiber permit its use as a reflector or an interferometer when pairs of gratings having the same reflectance characteristics are spaced along the optical fiber. The ruggedized fiber comprises an optical fiber having the outer cladding removed down to an inner sheathing wherein a portion of the inner sheathing is further removed to expose the core wherein evanescent waves are encountered. The gratings are formed in this core. Surrounding the gratings and connected to the inner sheathing are two semi-tubular sections which are affixed to the inner sheathing and hermetically sealed around the gratings.

Ruggedized grated optical fiber

The invention covers a process of forming gratings in optical fiber. The gratings are formed at depth wherein the evanescent waves of the optical fiber are encountered. The process permits the fabrication of gratings in the optical fiber that reflect light of predetermined wavelengths. The grated optical fibers can be used as reflectors or interferometers when the gratings are used in pairs.

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Kensington, MD, United States of America

Donald C Schmadel