Femtosecond pulse shaping via engineered nonlinear photonic crystals

Non-stationary second harmonic generation by femtosecond pulses, taking into account both group velocity mismatch and dispersion in nonlinear photonic crystals (quasi-phase matched crystals) with domains of arbitrary sizes has been studied numerically. A simulated-annealing algorithm, working on the basis of numerical calculation, is developed to design quasi-phase matching gratings which can yield the desired amplitude and phase profile for second-harmonic pulses in the presence of pump depletion.