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. This configuration, hitherto unapproached for PVF2 film Modulators, offers resonance at well-defined, controllable, and higher frequencies than possible for the flat-strip configuration. Significantly, two versions of this configuration are presented that achieve selective mode suppression or enhancement and hence provide a choice of the resonance frequency 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 leads to large reduction in the phase shift. A comparative study of the existing piezoelectric fiber-optic phase modulator designs is also presented.