Photorefractive damage resistance in Ti:PPLN waveguides with ridge geometry

A theoretical analysis of the photorefractive sensitivity of Ti:PPLN ridge waveguides in comparison with conventional Ti:PPLN channel waveguides is presented. In particular, intensity-dependent photorefraction, effective indices, waveguide modes and power-dependent SHG in Ti:PPLN ridge and channel waveguides are modeled for a wide range of parameters. Results predict a much better damage resistance of Ti:PPLN waveguides with ridge geometry in comparison with conventional indiffused channels. This superiority of ridge waveguides is attributed to their higher effective refractive index contrast and more tightly confined guided modes. The theoretical predictions are supported by experimental results for second harmonic generation (SHG) at room temperature and for light-induced detuning characteristics of the phase-matching wavelength.