Quantization Of Electromagnetic Field In Nonlinear And Inhomogeneous Absorbing Medium

Since the advent of laser, the interactions between laser and matter have become a hotspot and frontier of research in physics. Especially, mechanism of various radiations generated during interactive process is of considerable importance not only in the basis interest in academy but also in application. Simultaneously, the radiation is a quantum problem from its microcosmic mechanism. To understand the physical essence of radiation process in depth, imaginably, the development of a fully quantum mechanical description is necessary. In this thesis, quantizations of electromagnetic field in inhomogeneous and anisotropic absorptive dielectrics are theoretically investigated, using Langevin noise scheme. Subsequently, full quantum theory of Cherenkov radiation in an anisotropic absorbing media and radiation in laser plasma are explored by means of these quantization fields, and some worthful results are presented.The important results obtained are summed up as following:1. According to Langevin noise scheme, the wave equation with regard to Green function is analytically solved by direct integral method for a quadratic continuous nonlinear absorptive dielectric medium. The quantization of electromagnetic field in such a nonlinear absorptive dielectric is carried out for which the material dielectric function is assumed as separable variable about the frequency and the space coordinate. The vacuum field fluctuations for different spatial continuous variations of dielectric function are numerically calculated, which shows that the present result is self-consistent.2. A new approach is developed to solve the Green's function that satisfies the Hehmholtz equation with complex refractive index. Especially, the Green's function for the Helmholtz equation can be expressed in terms of a one-dimensional integral, which can convert Helmholtz equation into a Schrodinger equation with complex potential. And Schrodinger equation can be solved by Feynman path integral. Using this approach, the Green's function in arbitrary inhomogeneous absorptive dielectrics can be solved, which is useful for realizing electromagnetic field quantization in arbitrary inhomogeneous absorptive dielectrics.3. Based on Langevin noise scheme, we suggest a general approach to realize the quantization of radiation field in an anisotropic dispersive dielectric medium by defining a modified new coefficient of Langevin force operator. The transformation relation between the quantization methods for isotropic and anisotropic dispersive media is presented.4. The integral equation of modified coefficient satisfying in anisotropic absorptive dielectrics is discovered, which can realize electromagnetic field quantization in arbitrary anisotropic absorptive dielectrics.5. A fully quantum mechanical treatment is presented for the Cherenkov radiation stimulated by a uniformly moving charge particle in both isotopic medium and anisotropic medium. The relation between Cherenkov radiation intensity and dielectric tensor is analyzed. The results showed that, the medium dielectric tensor changes the density of the Cherenkov radiation but does not change the emitting angle of the radiation, which is of advantage for the collection of radiation wave with expectant wavelengths.6. Based on the Langevin noise approach, a full quantum theory of radiation in laser plasma is explored, where the laser power is limited to the range from 1010 W/cm2 to 1012 W/cm2 and the plasma is considered as a homogeneous dielectric background. By numerical calculation, the results show that the radiation is generated from resonance of the plasma and the emitted rate of photon depends on the angular relation of the directions of radiation fields as well as the motion of the unbounded free electrons. In addition, the photons are more easily created under the lower collision frequency.