Polarization-independent LiTaO/sub 3/ guided-wave electrooptic switches

Polarization-independent LiTaO/sub 3/ optical switches that utilize the off-diagonal electrooptic coefficient r/sub 51/ are discussed. The waveguides are formed by Zn vapor diffusion. Interguide transfer efficiencies of 84 and 88% for TM and TE polarizations, respectively, have been obtained. Modulation efficiency of 99.8% for TM and 95% for TE have been demonstrated at nearly equal voltages by thermally tuning to 20 degrees C. The relatively high voltage-length product (30-35 V-cm) attained in these initial devices at a 0.633- mu m wavelength is attributed to a weak overlap between optical and electrical fields in the periodic electrode structure.<
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