Abstract

Quadratic cascading response is evoked during the ultrafast and phase mismatched (cascading limit) second harmonic generation (SHG) process, which becomes more and more recognized alongside with typical nonlinear phenomena such as nonlinear phase change, pulse intrinsic self-steepening (SS) and material Raman effects. The mean value (local component) of this cascading response has been widely investigated and known as cascading quadratic nonlinearity (has a soliton number N_casc) which gives rise to a Kerr-like phase change and is tailored by the phase mismatch (∆k) between the fundamental wave (FW) and the second harmonic (SH) [1]. Moreover, the first order of the cascading response is revealed as an effective SS term [2,3], which adds to the intrinsic SS and induces shock front on pulses. Then, such SS effects will cause pulse delay when operating with material dispersions. Meanwhile, first order Raman response will also cause pulse delay by continuously red-shifting the pulse spectrum. Hence, there comes a pulse delay competition between the cascading and Raman responses.

© 2013 IEEE