Abstract

A TM wave excited in a Ti indiffused waveguide in LiNbO₃ was observed to change into TE at the waveguide output within times of the order of tens of seconds after "turn-on". The waveguides were fabricated in x cut y propagating LiNbO₃ and were single mode at the frequency of interest. The observations were made with λ = 6328 Å radiation at power levels of the order of 40 μw. The rate at which the changes take place is a function of the input power and it is not observed at very low power levels. An initial TE-excitation does not change into TM. In the simplest context, the phenomenon is tied to the well known "optical damage" in LiNbO₃. The explanation of the effect is complicated by the fact that the TE and TM waves are greatly phase-mismatched and no efficient coupling ought to occur between them.

© 1982 Optical Society of America