Abstract

We report a fiber-optic refractive-index sensor that is applicable to a long-distance measurement. The sensor consists of a silica glass fiber bent into a U shape with a bending radius of typically several hundred micrometers. The cladding at the tip of the sensor is stripped off. The sensing mechanism is based on the variation of the output intensity that is induced by radiation loss at the bend, which enables us to measure the refractive index of the outer medium. A fabrication method of fusing the sensor with a CO₂ laser and etching with HF is described. Multipoint measurements of optical-time-domain reflectometry are also described.

© 1992 Optical Society of America

Fiber Optics. Part IV. A Photorefractometer

N. S. Kapany and J. N. Pike
J. Opt. Soc. Am. 47(12) 1109-1117 (1957)

Photorefractometer I. Extension of Sensitivity and Range

N. S. Kapany and D. A. Pontarelli
Appl. Opt. 2(4) 425-430 (1963)

Photorefractometer II. Measurement of N and K

N. S. Kapany and D. A. Pontarelli
Appl. Opt. 2(10) 1043-1048 (1963)

Macrobending single-mode fiber-based refractometer

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Appl. Opt. 48(31) 6044-6049 (2009)

Optical time-domain reflectometry of bent plastic optical fibers

Tatsuya Sugita
Appl. Opt. 40(6) 897-905 (2001)