Theoretical analysis of optimal QPM-SHG waveguide structure in KTP substrates

Abstract

Based on the QPM structure, the "dead layer" effect on KTP substrates is qualitatively analyzed. Assuming the refractive index profile of an ion exchanged KTP channel waveguide is an exponential decay function in the depth direction, and a step-like function in the width direction, the analytical expression of the optical field distribution for the lowest order mode is obtained. According to the coupled-mode theory, the optimal QPM-SHG waveguide structure in KTP substrate with the "dead layer" effect are qualitatively discussed.