Results following from time-reversal symmetry are developed for those nonlinear optical processes where a statistical average is required. These generalize previous analyses by removing the electric dipole approximation and allowing for intermediate resonances. For example, Onsager relations for self-conjugate nonlinear optical processes (when input and output photons form degenerate pairs) are derived and associated reversality relations generalized. In the nonresonant limit magnetic-dipole but not electric-quadrupole terms in coherent processes are suppressed. For general processes purely electric dipole contributions to natural optical activity are possible when intermediate resonances are present.
Results following from time-reversal symmetry are developed for those nonlinear optical processes where a statistical average is required. These generalize previous analyses by removing the electric dipole approximation and allowing for intermediate resonances. For example, Onsager relations for self-conjugate nonlinear optical processes (when input and output photons form degenerate pairs) are derived and associated reversality relations generalized. In the nonresonant limit magnetic-dipole but not electric-quadrupole terms in coherent processes are suppressed. For general processes purely electric dipole contributions to natural optical activity are possible when intermediate resonances are present.
Electromagnetic Radiation 20time reversal, for the motion equations of quantum mechanics and the Hamiltonian of electromagnetic interaction are unchanged under time reversal.However, most processes related to laser and nonlinear optics are actually high nonequilibrium ones.As we known that time reversal symmetry will generally be violated in non-equilibrium processes.It is proved in this paper that after the retarded effect of radiation fields is taken into account, the time reversal symmetry will be violated in light's high order stimulated radiation and absorption processes with ml lm BB , although the Hamiltonian of electromagnetic interaction is still unchanged under time reversal.The transition probability of third order process is calculated and the revised formula of nonlinear optics polarizability is deduced in this paper.Many phenomena of time reversal symmetry violation in non-linear optics just as sum frequency, double frequency, different frequencies, double stable states, self-focusing and self-defocusing, echo phenomena, as well as optical self-transparence and self absorptions and so on are analyzed.The reason to cause symmetry violation is that some filial or partial transition processes of bounding state atoms are forbidden or can't be achieved due to the law of energy conservation.These restrictions can cause the symmetry violation of time reversal of other partial transition processes which can be actualized really.These realizable filial or partial processes which violate time reversal symmetry generally are just the practically observed physical processes.The symmetry violation is also relative to the initial state's asymmetries of bounding atoms before and after time reversal.For the electromagnetic interaction between non-bounding atoms and radiation fields, there is no this kind of symmetry violation of time reversal.For example, in the experiments of particle physics in accelerators, we can not observe the symmetry violation of time reversal.At last, the influences of symmetry violation of time reversal on the foundation theory of laser and non-equilibrium statistical physics are discussed.The phenomena of producing laser without the reversion of particle population and transition without radiation can be well explained.The result indicates that the irreversibility of evolution processes of macrosystems originates from the irreversibility of micro-processes.The irreversibility paradox can be eliminated thoroughly.By introducing retarded electromagnetic interaction, the forces between classical changed particles are not conservative ones.Based on them, we can establish the revised Liouville equation which is irreversible under time reversal.In this way, we can lay a really rational dynamic foundation for classical non-equilibrium statistical mechanics. The transition probability of the first order processFor simplification, we consider an atom with an electron in its external layer.Electron's mass is , charge is q .When there is no external interaction, the Hamiltonian and the wave function of electron are individually 2 2 0 ˆ2 HU r m 1 0 n Et n en (1) www.intechopen.comRetarded Electromagnetic Interaction and Symmetry Violation of Time Reversal in High Order Stimulated Radiation and Absorption Processes of Lights as Well as Nonlinear Optics ... 21 After external electromagnetic field is introduced, the interaction Hamiltonian is 2 2 2 ˆˆ ˆ2 qq HA pA q c c How to reference In order to correctly reference this scholarly work, feel free to copy and paste the following: Mei Xiaochun (2012).Retarded Electromagnetic Interaction and Symmetry Violation of Time Reversal in High Order Stimulated Radiation and Absorption Processes of Lights as well as Nonlinear Optics -Influence on Fundamental Theory of Laser and Non-Equilibrium Statistical Physi, Electromagnetic Radiation, Prof. S. O.
We develop a consistent formalism for the treatment of temporal atomic or molecular coherence in multiphoton absorption. The formalism is fully quantum mechanical under the assumption that the exciting laser fields are well described by coherent states. We make use of the language and methodology of resonance physics to the extent possible, but deliberately avoid the rotating-wave approximation, and do not restrict the allowed atomic states to be finite in number or the electric field strengths to be small in magnitude. For compactness in the presentation only electric dipole transitions are considered. As all of the transitions, both stimulated and spontaneous, are due to the activation of quantum mechanical dipoles, it is most efficient to construct the formalism so that it emphasizes the role of dipole operators, and we do this. The one strong restriction imposed here, but avoided in a following paper, is to consider only multiphoton transitions that have one resonance between initial and final states and no intermediate resonance. We describe, in effect, the time dependences associated with the early multiphoton absorption calculations of Bebb and Gold.
The principle of microscopic reversibility is a fundamental element in the formulation of fluctuation relations and Onsager reciprocal relations. As such, a clear description of whether and how this principle is adapted to the quantum-mechanical scenario might be essential for a better understanding of nonequilibrium quantum processes. Here, we propose a quantum generalization of this principle which highlights the role played by coherence in the symmetry relations involving the probability of observing a quantum transition and that of the corresponding time-reversed process. We study the implications of our findings in the framework of a qubit system interacting with a thermal reservoir and implement an optical experiment that simulates the dynamics. Our theoretical and experimental results show that the influence of coherence is more decisive at low temperatures and that the maximum departure from the classical case does not take place for maximally coherent states. Classical predictions are recovered in the appropriate limits.
A local-field theory describing optical phase conjugation in condensed media in the special case of degenerate four wave mixing is established. The aim of the theory is to form the framework for microscopic studies of optical phase conjugation (i) of evanescent fields in the context of near-field optics, (ii) in mesoscopic films and quantum wells, (iii) in small particles, and (iv) in lossy media where the field penetration depth is comparable to or (substantially) less than the vacuum wavelength of the driving field. The aforementioned goal makes it necessary to abandon both the slowly varying envelope- and the electric dipole approximations usually adopted in phase conjugation studies where spatially slowly decaying or modulated fields are mixed. By keeping in the interaction Hamiltonian the term of second order in the vector potential and in the current-density operator the term of first order in the vector potential new microscopic field-matter interaction processes of particular importance in the present context are included. The physics of the various nonlinear microscopic processes is analysed, and systematised by presenting in diagrammatic form the nonlocal electrodynamics hidden in the nonlinear constitutive relation. A new nonlocal conductivity tensor, enabling one to describe the degenerate four wave mixing process among the prevailing local fields, is presented and the eigensymmetries of its various parts are analysed. Starting from the general local-field theory a degenerate four wave mixing response tensor of relevance for media exhibiting two-dimensional translational invariance is established and discussed. In the last part of the paper an integral equation allowing one to obtain the phase conjugated local field inside and outside the nonlinear medium is established, discussed and formally solved, and it is pointed out that this equation for systems with two-dimensional translational invariance often can be analysed analytically and numerically using methods previously developed in theoretical studies of the linear local-field electrodynamics of mesoscopic films.
We show that second-order nonlinear optical processes such as sum and difference generation can be observed in isotropic media, despite the fact that such processes are forbidden in the electric-dipole approximation. A theoretical treatment of quadrupole sum- and difference-frequency generation is given, which includes the effects of spin-orbit and Zeeman splittings. The quadrupole nonlinear susceptibility is evaluated and expressions for phase matching and output power are found. We have generally confirmed the theoretical predictions by observing quadrupole sum-frequency generation of ultraviolet light in sodium vapor. Deviations of the data from the simple theory can be satisfactorily accounted for by the effects of two-photon saturation, induced index of refraction changes, and single- and multi-photon absorption. Generalization of the dipole forbidden susceptibilities to the case of quadrupole-pumped processes is discussed, with difference-frequency generation in Cs vapor considered as an example.