ELECTROOPTIC MODULATION AND SELF-POLING IN STRAIN-INDUCED WAVE-GUIDESIN BARIUM STRONTIUM-TITANATE NIOBATE

Characterization of bulk single crystals and optical waveguides in Ba1 -xSrxTiyNb2-yO6 (BSTN) indicate it to be a promising new ferroelectric material for electrooptic devices. The electro-optic coefficient r(33 ) is measured to be 218 +/- 12 pm/V, a factor of 7 greater than LiNbO3 . Data on refractive indices, dielectric constant, and Curie temperatu re T-c in bulk samples are also presented. Strain-induced waveguides i n Z-cut samples exhibited low losses (1.8 dB/cm for TM polarization an d 2.5 dB/cm for TE polarization) at a wavelength of 1.3 mu m. Electro- optic modulation was demonstrated in these waveguides to frequencies > 100 MHz. A ''self-poling'' effect was found, whereby strong electro-op tic modulation is observed in the strain waveguides without repoling t he crystal after processing at temperatures far above T-c. (C) 1995 Am erican Institute of Physics.