Gte Automatic Electric Laboratories Incorporated

Gte Automatic Electric Labs Inc.

Arthur H Fitch

Joseph Zucker

A method of determining splice loss 10 log (1-P.sub.R /P.sub.O) that is practiced at the location of a splice between one ends of input and output fibers. A reference level P.sub.O of light that is transmitted out of the one end of the input fiber is obtained by inserting it into an integrating cylinder of split block construction, prior to making the splice, and coupling diffuse light in the cylinder to a radiometer. After the ends of the fibers are spliced together, the splice and a significant portion of the adjacent length of output fiber exhibiting substantial leaky mode radiation that is caused by the splice, is located in the cylinder. With light of the reference level in the input fiber being incident on the splice, the radiometer provides an indication P.sub.R of light lost as a result of the splice. The indication P.sub.R may also be obtained by integrating only light radiated from a length of the leaky mode section of output fiber, which has been found to extend to approximately one foot downstream of the splice.

Method of measuring splice loss in optical fibers

A small amount of light that is transmitted in one of a pair of optical fibers having cleaved ends thereof loosely brought into butt contact is converted to leaky modes in the other fiber. Leaky mode light that is radiated out of the perimeter of the other fiber is collected in an integrating enclosure located proximate its one end and extending over a limited length of the other fiber. The light in the enclosure is detected for producing a measure of the degree of alignment of the adjacent ends of the fibers. After the cleaved ends of the fibers are aligned with micromanipulators so as to null the intensity of detected leaky mode radiation, an electrical arc is created across them for permanently joining the fiber ends together in a splice. The integrity of the resultant splice is determined by producing a measure of the splice loss 10 log (1-P.sub.R /P.sub.O), where P.sub.R is a measure of light scattered from the splice and/or radiated out of the perimeter of the leaky mode section of the other fiber for light of a radiant power P.sub.O in the one fiber and incident on the splice.

Method of splicing ends of optical fibers

Apparatus for field measurement of the insertion loss of a splice between one ends of first and second optical fibers comprises an integrating sphere that is split along its axis and which has a fiber input port, a pair of spaced-apart padded holes on the axis for receiving associated fibers so as to center the splice inside the sphere, and an output port receiving one end of a fiber bundle which couples diffuse light in the sphere to a radiometer. A baffle plate in the sphere prevents light rays from the splice being incident on the output port. The splice loss is determined by inserting the one end of the first fiber into the input port, with the other end illuminated by light from a source, and reading a reference level of light coupled to the radiometer. The two fibers are then spliced together and the splice located inside the sphere. With light of the reference level now incident on the splice, light scattered thereby is diffused in the sphere and coupled by bundle fibers to the radiometer which indicates the radiant power of scattered light. The splice loss is a function of the ratio of the indications of scattered and reference light.

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Redwood City, CA, United States of America

Arthur H Fitch