A quantum-mechanical description of a radiation-balanced solid-state laser is presented. The impurity ion levels are coupled both by the phonons of the host lattice and by the radiation field. The set of dynamic Heisenberg-Langevine equations for the material system and the phonon operators has been derived. These equations include
radiative and nonradiative damping terms and quantum-stochastic forces. This description could be used for investigation of the influence of phonon dynamics on laser stability.
The loss mechanism to account for the loss of laser photos from the cavity due to absorption by the second dopant inside the laser rod is investigated. We introduced a system of three-level ions as a dissipative subsystem and considered that photons can be lost through their coupling to this quantum subsystem. The conventional quantum laser theory is then expanded for this special case.
The method of elimination of boson operators is used to theoretically analyze the possibility and optimal conditions of superradiance regime of laser cooling of crystals and glasses doped with rare-earth ions. A set of kinetic equations governing the processes of laser cooling and optical superradiance in a multilevel system is derived for the pulsed regime. It is demonstrated that the efficiency of laser cooling in this regime is proportional to a factor N<SUP>2</SUP>(lambda) <SUP>2</SUP>Kn<SUB>S</SUB>, where N is the number of active impurity centers, (lambda) is the superradiance wavelength, K is the number of superradiance channels, and n<SUB>S</SUB> is the number of superradiance events per second.
The chain of kinetic equations for two-level and three-level macroscopic systems, interacting with the electromagnetic field, is obtained on the basis of the method of elimination of the boson variables, taking a new type of decoupling for three-particle correlators into account. These equations yield a better description of experimentally observed shape of super-radiant pulse than the standard theories based on the decoupling of the Tyablyakov's type.