Ultrabroadband Optical Phenomena in Quadratic Nonlinear Media

We present a comprehensive framework to study the nonlinear evolution of ultrabroadband optical pulses in quadratic nonlinear media. We employ a nonlinear envelope equation that goes beyond the traditional slowly varying approximation and allows treatment of all the harmonics by means of a single equation. We exploit this model to simulate recently observed supercontinuum phenomena such as ultrabroadband parametric downconversion and the generation of octave-spanning spectra from femtosecond pulses.