Influence of self- and cross-phase modulations on an optical frequency doubling process for metamaterials.

In the process of doubling the frequency of high-power laser radiation in metamaterials, the self- and cross-phase modulations associated with the cubic nonlinearity of the medium are studied in the constant-intensity approximation. It is assumed that the pump wave propagates in a region with negative refraction. It is shown that in the case of a nonlinear-optical process of frequency doubling of an intense light wave in a metamaterial, it is important to take into account the self-action and cross-interaction effects that directly affect the optimal phase relationship between the interacting waves.

Quasi-phase-matched intracavity laser frequency summation.

The work presents a theoretical analysis of quasi-phase-matched intracavity interaction in the constant-intensity approximation at frequencies summing with simultaneous regard for the losses and phases of interacting waves. An analytical expression for optimum correlation between interacting waves has been received. It is shown that, by the choice of optimum values of phase mismatch, pump intensity, and phase relationship, it is possible considerably to increase conversion efficiency in comparison with the noncavity case.

Frequency conversion to the second harmonic in different-layer nonlinear media.

The process of frequency conversion in a multilayer structure of different media with quadratic nonlinearity is investigated by using the constant-intensity approximation. The values of complex amplitudes of the fundamental radiation and the second harmonic at the outlet of each layer are the entrance values of the corresponding complex amplitudes of the next layer. Analytical expressions for second-harmonic conversion efficiency for the case of n layers are proposed.

Phase effects at fifth-harmonic generation.

The use of the constant intensity approximation in the theory of fifth-harmonic generation in dissipative media, with an account of reverse harmonic reaction on the exciting wave phase, has been developed. The optimal values of lengths for all three crystals when the conversion efficiency to the fifth harmonic is maximum have been obtained. It has been shown that, when the optimal parameter values of the problem are chosen, the high efficiency of the fifth-harmonic cascade generator can be reached.