Femtosecond supercontinuum generation and Čerenkov conical emission in periodically poled LiTaO3

We investigated the femtosecond supercontinuun generation and Čerenkov conical emission in periodically poled LiTaO3. A broadband spectrum was achieved from 380 nm to 440 nm and 490 nm to 970 nm. We have also demonstrated a novel way of calculating the nonlinear refractive index in the filamentation using Čerenkov radiation method. The nonlinear refractive index was about 0.024, it has the same order of magnitude with the refractive index change in proton-exchanged waveguide.