Abstract

The static and low-frequency pressure sensitivity of the optical phase in a single-mode fiber has been studied extensively as related to development of phase modulated interferometric fiber-optic sensors. In this low-frequency case, pressure applied to the fiber results in both axial and radial strains along the insonifted fiber. For ultrasonic frequencies, however, inertial effects do not permit a net axial strain contribution. We have studied analytically the fiber sensitivity to identify coatings which optimize the ultrasonic sensitivity of such axially constrained isotropic fibers. Both single-layer coatings and multilayer coatings are considered. Preliminary experimental results were found to be in agreement with the analysis.

© 1983 Optical Society of America