Temperature-insensitive quasi phase matching method for nonlinear frequency conversion

A temperature-insensitive quasi phase matching method is proposed to increase the temperature acceptance bandwidth in nonlinear optical frequency conversion. In the method, the nonlinear crystal is cut at an angle that enables the first temperature derivation of phase mismatching to be zero, which makes the phase mismatching value to be insensitive to temperature variation. Then, the phase velocities of mixing waves are quasi phase matched by appropriate poled period of the nonlinear crystal. Simulations of second harmonic generation of 1064 nm in periodically poled KTiOPO4 crystal and 5 mol% MgO-doped periodically poled LiNbO3 are conducted. The temperature acceptance bandwidths in periodically poled KTiOPO4 and 5 mol% MgO-doped periodically poled LiNbO3 reach 943 °C cm and 393 °C cm, respectively.