Bending effects in biconically tapered single-mode fibers

Biconically tapered single-mode fibers were fabricated, and their characteristics were studied experimentally. The optical throughput was measured as the fiber was being pulled to produce the required radial profile. The tapered single-mode fiber was bent in a simple fixture, and the optical throughput was measured as a function of the bending angle. It is seen that the bending resulted in very strong oscillations of the optical power as the bend angle was varied. At the point when the light in the core was minimal, the cladding region was bright, indicating that the light has moved to the cladding. The propagation characteristics of the tapered single-mode fiber subjected to bending are analyzed using a stepwise approximation. A simple sensor based on this principle is discussed