Improved sensitivity in sensor fibers by the proper source/coating selection.

The dependence of the optical attenuation on the fiber coating has been measured for a sensor fiber subjected to periodic microbending. The dependence on the spectral characteristics of the selected light sources is also addressed and the proper source/coating combination is discussed. Results indicate that the proper selection of this combination is of crucial importance in the design, development, and performance of fiber optic sensors in which intensity modulated microbending transducers are considered. A combination of a short wavelength for the light source and a fiber coated with a hard, elastomeric material seems to be the optimal selection for enhancing the sensitivity in controlled microbending experiments with applications to fiber optic sensors. The highest sensitivity to microbending was obtained for a nylon coated fiber and using a He-Ne laser at 632.8 nm.