Sound amplification by stimulated emission of radiation method of the pumping keeps the system electro-neutral and the dispersion laws of electrons and holes are assumed to be parabolic and isotropic. Also phonon dispersion law is required to be linear and isotropic too. Since the entire system is electro-neutral, the process of pumping creates electrons and holes with the same rate. A mathematical analysis, leads to an equation for the average number of electron-hole pairs per one phonon mode per unit volume. For a low loss limit, this equation gives us a pumping rate for the SASER that is rather moderate in comparison with usual phonon lasers on
Sound amplification by stimulated emission of radiation are more excited electrons than electrons in the lowest energy state in the system. As electron releases energy (e.g. phonon) it interacts with another excited electron to release its energy too. Therefore, we have a stimulated emission, which means a lot of energy (e.g., acoustic radiation, phonons) is released at the same time. One can mention that the stimulated emission is a procedure where we have a spontaneous and an induced emission at the same time. The induced emission comes from the pumping procedure and then is added to the spontaneous emission. A SASER device should consist of a pumping