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.