Nonlinear surface ultrasonic monopulses in solid film-substrate system

An excitation of ultra-high frequency (100 MHz - 1 GHz) nonlinear solitary acoustic waves, propagating along the interface between a solid film and a solid substrate, is theoretically analyzed. A quadratic elastic nonlinearity in both contacting media of the system is taken into account in the case of baseband waves. The Benjamin-Ono (B-O) type equation, due to the character of the linear wave dispersion, describes the baseband waves., but they are not true monopulse-like solitons and manifest as single shock-like pulses in the case of an excitation from the long initial rectangular pulse.