Enhanced harmonic generation in aperiodic optical superlattices

We find that harmonic generation can be enhanced with aperiodic optical sup erlattice (AOS) structures realized by inverting poled ferroelectric domain s in sample. The optimal design of the AOS can be achieved with use of the simulated annealing method. The constructed AOSs can implement multiple wav elength second-harmonic generation and the coupled third-harmonic generatio n with an identical effective nonlinear coefficient. The simulations show t hat the constructed AOSs can enhance harmonic generation compared with the Fibonacci optical superlattice. The physical origin of this enhancement is ascribed to the constructive interference effect. (C) 1999 American Institu te of Physics. [S0003-6951(99)03841-3].