Aetna Telecommunications Laboratories

Adc Fiber Optics Corporation

Glenn R Elion

Arthur R Nelson

A wide bandwidth, high sensitivity optical accelerometer having a lever arm to amplify the mechanical displacement of the accelerometer mass element. The optical accelerometer includes a high resonant-frequency spring-mass system, wherein the acceleration forces up to several hundred Hz cause a linear displacement of the mass with force, which, through the lever arm, modulates the intensity of a beam of light with a large gain. The modulated light beam is in turn converted to an electrical signal which corresponds to the applied accelerating force. The accelerometer of the present invention may be largely fabricated from a single piece of material such as silicon, wherein the lever, mass, spring and supporting structure are etched from a single substrate according to known photolithographic processes. Alternatively, the accelerometer components may be molded from a sheet plastic or other material. The accelerometer herein described provides a desired wide bandwidth and high sensitivity characteristic, and may be economically and accurately fabricated according to known manufacturing techniques.

Optical accelerometer

The optically transmissive fiber of a fiber optic cable is protected from degradation by corrosion from environmental fluids in high pressure and/or temperature environments. The light transmitting fiber is surrounded with one or more protective layers which contain finely divided particles, typically of the same composition as the corrodible components of the fiber, with the particles functioning to absorb and neutralize the corrosivity of the environmental fluids. These fluids cannot be entirely prevented from slowly penetrating the protective layers or coatings over time, particularly under the influence of the elevated temperatures or pressures. The particles are typically of a metal or metal oxide matching the metal or metal oxide constituent of the outer portions of the optical fiber itself. These particles typically are suspended in the polymeric, buffering layer directly surrounding the optical fiber. The particles are in a powdered form of micron size or smaller. This small size avoids micro bending losses typically associated with the presence of inhomogeneous layers adjacent to the optically transmitting fiber. Preferably before being buffer coated, the optical fiber is given a protective metal or metal oxide surface layer and a coupling agent layer may also be added between the fiber and buffer layer. This coupling layer is also doped with powders of the corrosion protecting elements. Outer layers such as cable sheathing may also include doping compounds to absorb or neutralize the corrosive environmental fluids.

Optical fiber protection by powder filled coatings

A process for manufacturing an optical fiber having a ceramic coating applied at the preform stage or drawn fiber stage wherein the coating hermetically seals the fiber against penetration of environmental gases and fluids and increases the fiber tensile strength, and a fiber produced by the process. An optical fiber preform, from which a fiber is to be drawn, preferably after a preliminary cleaning and drying, is coated with a ceramic layer by reacting hot gaseous compounds of tin or titanium with chlorine, bromine or iodine and water or hydrogen peroxide, typically with nitrogen or oxygen carrier gases. The reaction produces a thin ceramic preform coating of one or more layers of an oxide of tin, titanium, or tin with titanium. The thus coated preform is drawn to the dimensions of a desired optical fiber. The drawn fiber may itself be coated, typically in an on-line process fed directly from a drawing furnace, and comprising one or more reaction zones which apply a further or initial ceramic layer to the fiber. The thus coated or multiply coated fiber is typically buffer coated. Prior to the application of the buffer coating, the bonding between buffer and ceramic is improved by the application of a coupling enhancement compound.

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Northborough, MA, United States of America

Glenn R Elion