PLANAR FLEXIBLE FIBEROPTIC ACOUSTIC SENSORS

The acoustic sensitivity of optical fibers is considered analytically. High sensitivity is obtained with low bulk modulus, very thick polymeric coatings. The very thick coating limit has been realized by embedding optical fibers in an appropriate elastomer (polyurethane). A planar flexible fiber-optic interferometric acoustic sensor has been developed by wrapping optimized single-mode fibers in a planar spiral form, and then embedding the fiber in a thin polyurethane layer. The acoustic sensitivity of the sensor has been found to be high in frequency (0.2–2.5 kHz) and static pressure independent. The sensor was found to be compatible with water, and was compared favorably to that of a planar polyvinylidene fluoride sensor of similar geometry. © 1990 IEEE