Sound amplification by stimulated emission of radiation direct semiconductor. Consequently, the pumping of these transitions has to be very intense so as to obtain a steady laser generation. Hence, the lasing transition with production of only one particle – photon – must be resonant. This means that the lasing transition must be allowed by momentum and energy conservation laws to generate in a steady form. Photons have negligible wave vectors and therefore the band extremes have to be in the same position of the Brillouin zone . On the other hand, for devices such as SASERs, acoustic phonons have a considerable dispersion. According to dynamics, this leads
Sound amplification by stimulated emission of radiation introduced around 1995 The pumping is created by mechanical oscillations of a cylindrical resonator and the phase bunching of bubbles is realized by acoustic radiation forces. A notable fact is that gas bubbles can only oscillate under an external action, but not spontaneously. According to other proposed schemes, the electrostriction oscillations of the dispersed particle volumes in the cylindrical resonator are realized by an alternating electromagnetic field. However, a SASER scheme with an alternating electric field as the pump has a limitation. A very large amplitude of electric field (up to tens of kV/cm) is required to realize the amplification.