Thermal nonlinearity effect used in laser excitation of ultrasonic signals in geomaterials

The possibility of creating laser-ultrasonic sources of short power pulses of elastic longitudinal waves on the basis of nonlinear thermal processes in the generator medium is examined theoretically and experimentally. A three-dimensional model of thermal nonlinearity is considered, and the waveforms, spectra, and directional diagrams of signals excited in geomaterials are calculated.