Temperature and polarization dependence of LiNbO3 quasiphase-matched wavelength converters

Temperature and polarization characteristics of 1.55-μm-band LiNbO3 quasiphase-matched (QPM) wavelength converters have been studied by second-harmonic generation (SHG). It is found that the shift of the QPM wavelength is linearly proportional to temperature over the measured temperature range between 10 and 40 °C, with a temperature tolerance (corresponding to a 3 dB reduction in the QPM conversion efficiency) of greater than 10 °C for a 10-mm-long device. With respect to the angle θ of the injected fundamental light polarization direction, the SHG power changes as a function of sin4 θ, with a tolerance of over 60°. Theoretical explanations for the observed results are also presented.