Self-Steepening of Ultrashort Pulses without Self-Phase Modulation

Here we present a use of lambda
²
: lambda
²
nonlinearities that has no analog in cubic media. Through mixed quadratic and cubic nonlinearities in a frequency-doubling crystal we find the first manifestation of the Chen-Lee-Liu-type (CLL) derivative nonlinear Schrodinger equation (dNLSE) in nonlinear optics. In conclusion, we have observed novel optical effects by using a mix of quadratic and cubic nonlinearities. The observed effects are in agreement with a CLL-equation model of the pulse propagation, constituting the first observation of CLL-type dynamics in optics. The effects may have significant use in pulse-shaping applications.