Computational modeling of second-harmonic generation by solution of full-wave vector Maxwell equations

A numerical study of second-harmonic generation based on direct solutions of full-wave vector Maxwell equations, conducted by use of a finite-difference time-domain scheme, is reported. Although nonlinear problems have already been solved by finite-difference time-domain schemes, this is the first finite-difference time-domain computation of second-harmonic generation in a nonlinear crystal with a complete description of the electric field. Only spatially plane waves are considered, but the three components of the electric field are taken into account. The advantages and the drawbacks of this new approach are shown: On the one hand, all the spectral components of the waves are computed, but, on the other, the phase mismatch, which is imposed rather than computed, requires the use of a fine temporal mesh. The numerical results obtained for second-harmonic generation of femtosecond pulses in a thin KDP crystal are compared with those obtained by solution of the nonlinear Schrodinger equations. They illustrate the advantages of this method. (C) 2000 Optical Society of America [S0740-3224(00)00201-0].