Low-loss, damage-resistant optical waveguides in Zn-diffused LiNbO3 by a two-step procedure

In the present work the fabrication of high-quality LiNbO3 waveguides, base d on Zn diffusion from vapor phase using a two-step diffusion process, has been demonstrated. The optical waveguides fabricated using this method have low propagation losses (less than 0.5 dB/cm measured at 633 nm), as a cons equence of the high surface quality obtained. High photorefractive damage r esistance is reported, and it has been related to the Zn incorporation into the LiNbO3 crystals. Additional advantages of this waveguide fabrication m ethod due to the low temperature of the process (< 900 degreesC) are to pre vent Li out-diffusion and to preserve ferroelectric domain structures.