100 MHZ-BANDWIDTH RESPONSE OF A FIBER PHASE MODULATOR WITH THIN PIEZOELECTRIC JACKET

100 MHz-bandwidth response of an all-fiber phase modulator composed of a single-mode optical fiber jacketed with a 10 mum-thick vinylidene fluoride/trifluoroethylene copolymer, radially poled is presented. Multiple peaks of optical phase shifts induced are observed over the frequency range of 10-100 MHz and ascribed to radial resonances of a fiber-jacket composite. The theoretical analysis of phase shifts is performed based on vibration theory of elasticity taking the exact geometry and composition of the cylindrical multilayer structure into account. The analysis also shows that the phase modulation is strongly dependent on jacket thickness and the maximum induced phase shift will be obtained in the 100 MHz region when the jacket is chosen to be thin as 0.7 mum.