NONEQUILIBRIUM STATES OF CHARGE CARRIERS IN SUPERCONDUCTORS: POSSIBILITIES TO CREATE INVERSE POPULATION AND INITIATE LASER ACTION

Abstract

Distribution functions of nonequilibrium electron-hole excitations are considered in superconductors under the external pumping. In isotropic superconductors with the Debye-like phonon spectrum, the inverse population theoretically may be created only at the tunnel injection of electrons from massive superconductor into thin superconducting film. In superconductors with non-Debye spectrum, particularly in anisotropic single crystals, in which the interaction of electrons with transverse phonon modes may become significant, the situation is much more preferable. Recently, it has been shown that the electron system of such superconductors can be shifted ultimately far from thermal equilibrium state by the incident light. Thus, the possibilities exist for the creation of generators of coherent electromagnetic radiation on the basis of superconducting active media.