On the generation of radiation of different natures

Abstract

The book discusses the nature and consequences of competition between different types of radiation - spontaneous and induced, as well as superradiation in quantum and classical systems. Near the new threshold for the generation of stimulated radiation, the mechanism of formation of characteristic triangular pulses of this radiation against the background of the spontaneous field of quantum sources is considered. The formation of such pulses in outer space is discussed. Based on these ideas, a model is presented to describe the periodic change in the luminosity of Cepheid stars. The work also compares the nature of oscillation generation by an ensemble of quantum and classical emitters in open systems for two cases: during excitation of waveguides and in superradiance modes. In the first case, the traditional description is used - that is, emitters and oscillators interact only with the field of an open resonator or waveguide, the spatial distribution of which is initially specified. In the second case, on the contrary, the emitters and oscillators interact only with each other, in particular, in the absence of resonator or waveguide fields. This type of excitation is characteristic of the superradiance regime. For the same ensemble of emitters and oscillators, the characteristic times (reverse increments) of the development of these two processes and the achievable field amplitudes (at the same level of energy losses due to radiation) turn out to be similar. For a system of nonlinear oscillators, constant pumping modes are considered and the RF field pressure, which causes the movement of the oscillators, is taken into account. The influence of noise on the process of superradiation is considered. Under these conditions, methods for initiating generation by an external field are considered, and the nature of the formation of resonator and waveguide fields due to reflection effects is discussed. The processes discussed are revealed in the behavior of systems of classical oscillators, as well as when considering the generation of cyclotron waves by an electron flow in a magnetically active waveguide. In all cases, if the conditions for generating the total field of interacting emitters or oscillators are met, in the absence of reflection from the ends of the system, this superradiance mode dominates. And only in the presence of processes of field reflection from the ends, noticeably larger resonator or waveguide fields are formed. The injection of particles into the system and the high speed of their drift also increase the amplitude of the resonator and waveguide fields.