FREQUENCY-RESPONSE AND PHASE-SHIFT NONLINEARITY OF A CYLINDRICAL PVF(2)-FILM-BASED FIBEROPTIC PHASE MODULATOR

A new cylindrical coil configuration for polyvinylidene flouride (PVF2 )-film-based fiber-optic phase modulator is studied for the frequency response and nonlinearity of phase shift at the resonant frequency. Th is configuration, hitherto unapproached for PVF2 film Modulators, offe rs resonance at well-defined, controllable, and higher frequencies tha n possible for the flat-strip configuration. Significantly, two versio ns of this configuration are presented that achieve selective mode sup pression or enhancement and hence provide a choice of the resonance fr equency at which a large phase shift occurs. It is shown that the coil version in which the fiber loops are bonded strongly to each other le ads to large reduction in the phase shift. A comparative study of the existing piezoelectric fiber-optic phase modulator designs is also pre sented.