Transverse Magnetic (TM) Guided-Transverse Electric (TE) Radiation Mode Conversion in Proton-Exchanged Z-Cut LiNbO3 Waveguides

The mechanism of transverse magnetic (TM) guided to transverse electric (TE) radiation mode conversion losses in proton-exchanged z -cut LiNbO 3 waveguides was investigated experimentally. These mode conversion losses are caused by strains in the proton-exchanged regions. To clarify the mechanism, the influence of both external electric fields and propagation directions on the conversion efficiencies were measured, and a model of the strain induced by proton exchange is presented.