Multiple-beam interferometric determination of Poisson’s ratio and strain distribution profiles along the cross section of bent single-mode optical fibers

Multiple-beam Fizeau fringes crossing bent single-mode optical fibers immersed in matching liquid reveal the existence of induced birefringence. Changes in the fiber cladding refractive index delta n were measured from the fringe shift to an accuracy of +/- 1 x 10(-4). Mathematical expressions were deduced to evaluate Poisson's ratio and to describe the radial strain distribution profiles of bent optical fibers from the experimental values of the fringe shifts. Experimental results were obtained from microinterferograms. Studying bent fibers by application of Fizeau fringes interferometry provides a nondestructive, accurate, sensitive, and reliable method to measure their parameters and characteristics.