Generation of Picosecond Acoustic Pulses by Laser Radiation in Piezosemiconductors

Theoretical description is proposed of the frequency spectrum of strain pulses, excited by optical generation of nonequilibrium charge carriers in piezocrystals. The acoustic pulses are excited by the inverse piezoeffect by electric fields induced by spatial separation of electrons and holes. The conditions necessary for picosecond strain pulse generation are determined. The possibility of acoustic pulse excitation with duration governed by Debye screening time is predicted. It is shown that piezomechanism of optoacoustic transformation may be more effective than thermoelastic and electronic mechanisms.