Generation of coherent phonon pulses by hot electrons in non-crystalline semiconductors

We study the cooperative generation of phonon pulses in semiconductors by groups of inverted equidistant multilevel coupled excitations (electrons, excitons). Such equidistant systems take place in chalcogenide glasses with fractal structure. It is demonstrated that the cooperative generation of non-equilibrium localized phonons can be observed in experimental studying of the relaxation of groups of excited atoms after the passage of short laser pulse through the glass sample. The increasing of the absorption coefficient in the process of the excitation of glasses by short laser pulse with relatively small power is conditioned by the generation of the non-equilibrium coherent localized phonons in the process of the relaxation of non-equilibrium excitations. These coherent non-equilibrium localized phonons strongly change the topology of the random potential and, thus, open a new channel of the interband light absorption. These transitions take place with simultaneous participation of the photons and localized phonons.