An all-fiber Fabry-Perot interferometer using coherence demultiplexing and rugate mirror reflectors grown with electron cyclotron resonance plasma enhanced chemical vapor deposition (ECR-PECVD) on the fiber ends is proposed. The interferometer consists of a laser diode source, two optical fiber cavities, three rugate mirrors, a phase modulator and phase detection system. Coherence demultiplexing allowed the use of fiber cavities of several meters in length with a partially coherent illuminating light source. Truly inhomogeneous refractive index mirrors were designed taking into account dispersion and losses of SiO_xN_y at the required wavelength of 1.3 micrometers . The reflectance/transmittance ratio during growth were adjustable from 0.05/0.95 to 0.95/0.05 and mirrors used in the experimental interferometer had no inal reflectances of 40%, 68%, and 40% respectively. Design and fabrication procedures permit implementation of window functions and matching layers for flexible control over transmittance and reflectance charateristics. The long-cavity Fabry-Perot sensor was demonstrated for use as a strain gauge. Good agreement was shown with results obtained by a conventional strain gauge.

Date Published: 25 September 1995
PDF: 9 pages
Proc. SPIE 2510, Fiber Optic and Laser Sensors XIII, (25 September 1995); doi: 10.1117/12.221714

Published in SPIE Proceedings Vol. 2510:
Fiber Optic and Laser Sensors XIII
Ramon P. DePaula; John W. Berthold III, Editor(s)