Čerenkov difference frequency generation in a two-dimensional nonlinear photonic crystal

Abstract

We present experimental realization of Čerenkov difference frequency generation (CDFG) in a 2-dimentional rectangular periodically poled LiTaO3. The backward reciprocal vector of the nonlinear photonic crystal accelerates the phase velocity of the nonlinear polarization wave so as to exceed the phase speed limit of achieving Čerenkov down-conversions in this normal dispersion medium. Some characteristics of CDFG, such as radiation angles, pumping power, and pulse temporal overlapping dependences were discussed. The experimental results matched well with theoretical predictions.