and made piezoactive

radial poling. A flat response of optical phase shifts is observed in the frequencyrange over 10KHz to 3 MHz whereas at frequencies higher than 4MHz it shows multiplepeaks dominated by radial resonances of the fiber—jacket composite. An excellentagreement exists between the experimental data and theoretical calculations based onradial vibration analysis.1. INTRODUCTIONAll—fiber components associated with passive and active optical functions suchas coupling, multiplexing and demultiplexing, switching as well as modulating haverecently received considerable attention"2, mainly because of the strong potential