WATER-VAPOR EFFECTS ON OPTICAL CHARACTERISTICS IN TI-LINBO3 CHANNEL WAVE-GUIDES

This paper describes experimental studies on propagation loss and crosstalk of TM-polarized light in Ti-diffused Z-cut LiNbO3 channel waveguides as a function of the water vapor content in the diffusion atmosphere. The dependence of surface roughness and crystal quality on the waveguide fabrication atmosphere is taken into consideration. In this study it is found that waveguides with low propagation loss (< 0.2 dB/cm), low crosstalk (< -20 dB), and smooth surfaces can be fabricated by strictly controlling the water vapor content introduced into the oxygen or argon carrier gas.