Formation And Properties Of Optical Waveguides In Strontium Barium Niobate (Sbn:60)

Single mode channel and planar waveguides have been formed in strontium barium niobate Sr0.6 Ba0.4Nb206 (SBN:60) by sulfur indiffusion.1 The vapor diffusion is performed in a sealed ampule and is followed by oxidation in an open tube. Present channel waveguide losses are high: approximately 15-20 dB/cm for the TM mode and 27-32 dB/cm for the TE mode in Z-cut substrates. After poling of the substrate, electro-optic modulation was observed. The effective electro-optic coefficient was determined experimentally as 3.3 ± 0.2 x 10-10 m/V (over the frequency range 100 Hz-1 MHz) which is about 15 times greater than for the commonly used integrated optical materials, LiNbO3 and LiTaO3. Diffusions were conducted with the S35 radio-isotope in order to determine the sulfur distribution within the SBN. The atomic sulfur concentration was estimated to be approximately 4 x 1017 cm-3 in the region from the surface to a 2.5 tim depth and there was still a significant concentration (approximately an order of magnitude smaller) at depths of > 20 μm.