Optimum formation of the response of aperiodic nonlinear crystals in the process of second harmonic generation

The theory of second harmonic generation in nonlinear optical crystals that is caused by the quasiphase-matched interaction of the waves with a random domain structure is developed. The theoretical analysis is performed using the approximation of the intensity fixed within the domain length. It is shown that the developed method allows one to accurately describe the energy exchange between the interacting waves at any values of the efficiency of second harmonic generation. Within the framework of the developed theory, the so-called simulated-annealing algorithm for the formation of the response of the medium is created, which is responsible for the spectral dependence of the efficiency of the second harmonic generation with any specified profiles under conditions of energy depletion of the fundamental radiation.