This thesis treats the coherent interaction of light quantum with a crystal, taking proper account of the mutual interactions of the individual scatterers. Of particular interest is the case of resonant scattering. Using the Feynman approach to quantum electrodynamics, we first develop the general ideas with one- and two-particle systems. The major results are then presented in sections V and VI. [see PDF for formulas] In section V we derive a general quantum expression governing the coherent optical properties of an N particle system: In section VI we use these results to treat resonant optics. It is found that at certain well defined frequencies and angles, the interactions among the resonators can lead to a greatly enhanced coherent width, and therefore to suppression of incoherent processes such as inelastic scattering and absorption. It will be shown that for certain conditions, this width enhancement causes anomolously high transmission or reflection.
This thesis treats the coherent interaction of light quantum with a crystal, taking proper account of the mutual interactions of the individual scatterers. Of particular interest is the case of resonant scattering. Using the Feynman approach to quantum electrodynamics, we first develop the general ideas with one- and two-particle systems. The major results are then presented in sections V and VI. [see PDF for formulas] In section V we derive a general quantum expression governing the coherent optical properties of an N particle system: In section VI we use these results to treat resonant optics. It is found that at certain well defined frequencies and angles, the interactions among the resonators can lead to a greatly enhanced coherent width, and therefore to suppression of incoherent processes such as inelastic scattering and absorption. It will be shown that for certain conditions, this width enhancement causes anomolously high transmission or reflection.
The subject of the review is the diffraction of an electromagnetic wave on a periodic condensed matter where the Bragg condition is satisfied at the frequency of resonance excited in this medium. The Bragg systems known as resonant photonic crystals in general have been considered, and the propagation, reflection, transmission, and diffraction of electromagnetic radiation in different objects—(I) periodic quantum-well structures near the exciton resonance, (II) optical lattices of atoms cooled in a laser field, and (III) bulk crystals and multilayers with gamma-ray resonance intranuclear transitions—have been described in a unified context. The main attention has been paid to the steady-state linear diffraction, including resonant reflection and transmission, which is the best studied and allows a comparison of the three aforementioned systems with the aim of revealing specific characteristics and common features. A characteristic common property of the considered systems is the suppression of non-radiative channels and an inhomogeneous broadening of the resonance frequency. The second fundamental property of resonant photonic crystals is that the interaction of light with resonant excitation can occur in two regimes depending on the thickness of the sample. In the superradiant regime realized for a small number of resonant layers N (fine structures), the height of the peak and half-width of the reflection spectrum monotonically increase with increasing value of N. With a further increase in N, there occurs a transition to a photonic-crystal regime where the half-width of the reflection spectrum is saturated, which manifests itself in the form of an optical stop band. The theoretical description is illustrated by experimental spectra measured for all three resonant Bragg systems.
This thesis concerns the theoretical investigation of interference phenomena related to elastic and inelastic scattering of quantized light. The presented work is naturally divided into two parts, the first is concerning elastic scattering while the second explores inelastic scattering. In the first part we use a scattering-matrix formalism combined with results from random-matrix theory to investigate the interference of quantum optical states on a multiple scattering medium. We investigate a single realization of a scattering medium thereby showing that it is possible to create entangled states by interference of squeezed beams. Mixing photon states on the single realization also shows that quantum interference naturally arises by interfering quantum states. We further investigate the ensemble averaged transmission properties of the quantized light and see that the induced quantum interference survives even after disorder averaging. The quantum interference manifests itself through increased photon correlations. Furthermore, the theoretical description of a measurement procedure is presented. In this work we relate the noise power spectrum of the total transmitted or reflected light to the photon correlations after ensemble averaging. This analysis enables us to describe an experimental observation of the quantum nature of light that survives the averaging over disorder. In the second part we investigate inelastic scattering. This we do by first treating the scattering of light on dipoles embedded in an arbitrary dielectric environment. By considering the two different models for dipole interaction known as the minimal-coupling and electric-dipole interaction Hamiltonians, we find exact relations between the electric field and the dipole operators in the Heisenberg picture, while keeping the model of the dipoles arbitrary. Due to the exact treatment of the electric-field operators, we obtain kernels known from classical scattering theory to describe the propagation of the field from the dipoles. Using the found electric field operators we derive the Heisenberg equations of motion for the dipoles while treating them as quantum two-level systems and using the Born–Markov and rotating-wave approximations. Postponing the rotating-wave approximation to the very end of the formal calculations allows us to identify the different physical parameters of the dipole evolution in terms of physical quantities known from optics. Finally, we use our Heisenberg picture formalism to treat a dilute cloud of two-level atoms, by simplifying the equations of motion using a single-scattering approximation for the interaction between the atoms. This enables us to derive expressions for the steady-state population and fluorescence spectrum, where we find cooperative effects in both the elastic and the inelastic spectra.
This book presents a systematic account of optical coherence theory within the framework of classical optics, as applied to such topics as radiation from sources of different states of coherence, foundations of radiometry, effects of source coherence on the spectra of radiated fields, coherence theory of laser modes, and scattering of partially coherent light by random media. The book starts with a full mathematical introduction to the subject area and each chapter concludes with a set of exercises. The authors are renowned scientists and have made substantial contributions to many of the topics treated in the book. Much of the book is based on courses given by them at universities, scientific meetings and laboratories throughout the world. This book will undoubtedly become an indispensable aid to scientists and engineers concerned with modern optics, as well as to teachers and graduate students of physics and engineering.
The exponentially decaying semi-stationary states of an assembly of identical classical radiators can have decay rates and resonant frequencies significantly different from that of an isolated radiator. These coherent effects on classical radiators emitting classical waves apply also to the particle processes in quantum limits, leading to the superradiant and subradiant modes with widths(decay rates) greatly enhanced or suppressed and resonant energies significantly shifted. The purpose of this thesis is to investigate these coherent effects on slow neutron-heavy nuclei interaction. A simple field model is introduced to show the coherent effects on the decay rates and resonant energies of two identical decaying states and on the neutron widths and resonant energies of neutron-two nuclei scattering. The latter case is also obtained by multiple scattering theory and is extended to a more general case of neutron-N nuclei scattering. The coherent effects on neutron width near Bragg angle in a crystal are also investigated.
A theory for the response of a 2 D two-level system to irradiation by a symmetric light pulse is developed. Under certain conditions, such an electron system approximates an ideal solitary quantum well in a zero field or a strong magnetic field H perpendicular to the plane of the well. One of the energy levels is the ground state of the system, while the other is a discrete excited state with energy ℏω 0 , which may be an exciton level for H =0 or any level in a strong magnetic field. It is assumed that the effect of other energy levels and the interaction of light with the lattice can be ignored. General formulas are derived for the time dependence of the dimensionless “coefficients” of the reflection ℛ( t ), absorption A ( t ), and transmission ℐ( t ) for a symmetric light pulse. It is shown that the ℛ( t ), A ( t ), and ℐ( t ) time dependences have singular points of three types. At points t 0 of the first type, A ( t 0 )= T ( t 0 )=0 and total reflection takes place. It is shown that for γ r ≫γ, where γ r and γ are the radiative and nonradiative reciprocal lifetimes, respectively, for the upper energy level of the two-level system, the amplitude and shape of the transmitted pulse can change significantly under the resonance ω l =ω 0 . In the case of a long pulse, when γ l <γ r , the pulse is reflected almost completely. (The quantity γ l characterizes the duration of the exciting pulse.) In the case of an intermediate pulse duration γ l ≅γ r , the reflection, absorption, and transmission are comparable in value and the shape of the transmitted pulse differs considerably from the shape of the exciting pulse: the transmitted pulse has two peaks due to the existence of the point t 0 of total reflection, at which the transmission is zero. If the carrier frequency ω l of light differs from the resonance frequency ω 0 , the oscillating ℛ( t ), A ( t ), and ℐ( t ) time dependences are observed at the frequency Δω=ω l −ω 0 . Oscillations can be observed most conveniently for Δω≅γ l . The position of the singular points of total absorption, reflection, and transparency is studied for the case when ω l differs from the resonance frequency.
This book is devoted to the modern problems of quantum optics. Atomic radiations in free space, waveguides, cavities and periodical structures are investigated. The wavepacket quantum-mechanical picture of radiation is stressed and different quantum states of the radiation field are described. The analysis of the appearance of coherence in lasers is followed by a discussion of the connection between the form of the Hamiltonian and the initial conditions in the radiation problems. The quantum theory of interference is also given and causality in the radiation process is investigated, and the resolvent method for radiation problems is also described. A new type of laser generator with an extremely narrow spectrum is then proposed. Finally, problems of the quantum-mechanical description of macroscopic body movement are discussed in connection with the observation of squeezed light.