LAUSR

Oscillation and wave excitation processes are investigated in systems with quadratic nonlinearity in the presence of selective absorption at second harmonic frequency. Specific examples are considered: wave excitation by sources moving with velocity close to that of natural disturbances in the medium, wave excitation in a plane layer (one-dimensional resonator) by oscillation of one of the walls, and forced oscillations of two coupled oscillators. It is shown that, as the second harmonic absorption factor increases, the fundamental oscillation amplitude grows. Similar relation holds for nondispersive nonlinear waves characterized by shock wave formation and energy “spread” to higher harmonics. Second harmonic suppression “blocks” the cascade process of energy transfer toward upper part of the spectrum and “turns off” nonlinear absorption. Some of the systems under consideration had been implemented and experimentally investigated. Selectively absorbing media designed for high-frequency waves can be considered as metamaterials and synthesized on the basis of corresponding technologies.