Phase and group synchronization in second-harmonic generation of ultrashort light pulses in one-dimensional photonic crystals

It is shown, on the basis of an analysis of the dispersion relation for an infinite one-dimensional periodic multilayer structure and direct numerical integration of Maxwell's equations by the finite-difference method, that s tructures with photonic band gaps (PBGs) make it possible to provide simult aneously conditions for phase and group synchronizations for second-harmoni c generation with participation of extremely short light pulses. The phase and group detunings, which arise as a result of the dispersion of the nonli near medium, are compensated by the dispersion of the PBG structure. The us e of this regime of nonlinearly optical interactions opens up the possibili ty of attaining high frequency conversion efficiencies irrespective of the synchronization length in the interior volume of a nonlinear material. (C) 2000 MAIK "Nauka/Interperiodica".