Studies On The Propagation Of Several Types Of Laser Beams Through Random And Determinate Media

Laser beams interacting with media plays an important role in the study of laser physics. During the past decades, due to the practical requirement in the fields of optical communications, military, medical diagnosis, materials processing and so on, the propagation properties of optical beams through various media have been widely investigated. Among them, a good deal of attention has been paid on various laser beams on propagation in atmosphere. Ocean is another important natural turbulence, however, oceanic turbulence has not been explored as extensively as atmospheric turbulence has due to its complexity. Until recently, a new model of spatial power spectrum of oceanic turbulence has been introduced. On the other hand, most of the studies concerning partially coherent beams are confined to the Gaussian Schell-model beams, in recent years, many random sources with non-Gaussian correlations have been introduced. More and more attention has been paid to these beams with special correlations due to their distinctive propagating characteristics, such as self-splitting, self-shifting, self-focusing and so on. In the context, on the basic of the theory of coherence and polarization, the propagation of various laser beams including, electromagnetic beams, array beams, stochastic vortex beams, and non-Gaussian correlation pulses through determinate and random media are investigated in detail. The influences of source correlations and the media parameters on the statistical properties are discussed.The dissertation is arranged as follows:In Chapter 1, the background and the status in related fields are introduced. Though analyzing the development process of light wave propagation home and abroad, we present the motivation and the significance of our research. Then the theoretical basis and fundamental methods are introduced, including:mutual coherence function and cross-spectral density; the cross-spectral density matrix; the theory of the diffraction integral; theory of lasers propagating in turbulence; models of atmospheric turbulence and oceanic turbulence; theory of devising genuine spatial correlation function.In Chapter 2, the propagation properties of several electromagnetic beams in oceanic turbulence are studied. Firstly, a radially polarized beam is taken as an example, and we investigated the interaction of coherent electromagnetic beams with oceanic turbulence. Based on the extended Huygens-Fresnel diffraction integral and the unified theory of coherence and polarization of light, the elements of the cross-spectral density matrix have been derived, and the spectral density, the spectral degree of polarization, and the beam quality of the beam on propagation are discussed. Then with the help of vector integration, we reveal the spectral changes in stochastic anisotropic electromagnetic Gaussian Schell-model beams propagating through a homogeneous and isotropic turbulent ocean, and determines the effects of the turbulence parameters on the changes. At last, we discuss the influence of astigmatism on electromagnetic non-Gaussian correlated random beams on propagation. An electromagnetic non-uniformly correlated source is used as an example, we explore the behavior of aberrant electromagnetic non-uniformly correlated beams propagating in the presence of turbulent ocean, and determine the effects of astigmatism on spectra distribution and degree of polarization.In Chapter 3, the spreading regions of array beams propagating though turbulent ocean is examined. Based on the mean-squared beam width, we discuss the Rayleigh range and two turbulence distances of one-dimensional Gaussian array beams in uniform oceanic turbulence. The effects of the array beam parameters (waist width, beam number, separation), the strength of turbulent ocean, and the combination form on spreading regions are stressed.In Chapter 4, the evolution of non-Gaussian correlated vortex beams propagating in random media is investigated. To illustrate the theory, the multi-Gaussian Schell-model vortex beams through non-Kolmogorov turbulence is taken as an example, and the dependence of the spectral density, the degree of coherence and the turbulence-induced spreading on source correlations, the vortex phase and the medium parameters are studied in detail.In Chapter 5, the recently introduced scalar sinc-Schell model pulsed source is extended to the full electromagnetic domain, and we focus on the evolution of the statistical properties of electromagnetic sinc-Schell model pulses in dispersive media. The effects of the temporal coherence length of sources and the dispersion dispersive coefficient of medium on the profiles of temporal intensity and temporal polarization are also emphasized.