Time Domain Modeling of Induced Birefringence and Phase Shift in Piezoelectric Resonance Enhanced Electrooptic Modulators

摘要

In our continuing effort of developing electromagnetic-electromechanical-electrooptic interactive devices, the effect of piezoelectric resonance on the performance of electrooptic modulators is investigated. Time domain finite element models were constructed to determine the phase shift due to the induced birefringence of the device. Two sinusoidal voltage sources are used one to sweep over a range of frequencies while the other setting the modulator at a selected resonance frequency. Ferroelectric single crystals such as LiNbO_3 and Pb(Zn_(1/3)Nb_(2/3))O_3-PbTiO_3, were examined for their induced index of refraction, the induced phase shift, and the half-wave voltage of given configurations. The time domain model of dual signal ac biased configuration displayed wide bandwidth enhancement when biased at proper resonant modes, which matches well with experimental observations. The results demonstrate the piezoresonant enhancement in terms of low half wave voltage and high electrooptic coefficients in broad frequency ranges. The results also provided corresponding insights that further our understanding on experimental observations reported previously by the authors. The models are suitable for designing of electrooptic device configurations that optimize the properties desired.