Soviet Journal of Quantum Electronics

Negative absorption of light by a medium exhibiting selective frequency modulation of quantum oscillators

Лев Абрамович Ривлин

Published Mar 31, 1980• 1 citation

Abstract

An analysis is made of the appearance of negative absorption as a result of inhomogeneous deformation of the spectral functions of excited and unexcited radiators when they are subject to frequency (for example, Doppler) modulation. The problem of stimulated emission of γ rays is considered specifically.

DOI: 10.1070/qe1980v010n03abeh010006

Related papers

Mössbauer medium with a hidden nuclear population inversion and negative absorption of gamma quanta

Лев Абрамович Ривлин

We consider physical foundations of an eventual experiment aimed at observing stimulated gamma-photon emission of long-lived Mössbauer isomers through selective frequency modulation of gamma-resonances establishing hidden population inversion without exceeding the number of excited nuclei over unexcited ones and without additional pumping. The examples of suitable nuclei and numerical estimates of the parameters are presented.

Quantum ElectronicsJun 30, 20110 citations

Dynamic holograms in amplifying medium

Е. В. Ивакин, I. P. Petrovich, Alexander S. Rubanov +1 more

An investigation was made of the formation of dynamic holograms in media with a negative absorption coefficient. Recording and/or reconstruction of a wave front under these conditions resulted in an increase of the intensity of the light fluxes. When feedback was sufficiently strong, a dynamic hologram (recorded in an excited system by spatial modulation of the gain) generated radiation with a specified spatial-temporal spectrum.

Soviet Journal of Quantum ElectronicsJul 31, 197510 citations

Spectroscopy of a resonance medium based on the use of nonlinear absorption of strong polychromatic radiation with equidistant spectrum

G. I. Toptygina, Evald E. Fradkin

Let us consider preliminary two situations. In the first of them the monochromatic radiation is absorbing. The increase of its intensity leads to the diminution of an absorption down to zero in a limiting case, i.e. to the effect of saturated absorption. In the second case an absorption of test radiation with a small intensity is observing, while two—level atom is strongly interacting with a perturbing field. This case is characterized by asymmetric dependence of absorption on the frequency difference w- w = A, where w and w are the frequencies of two light waves. As it was shown by Rautian and Sobelman in 19611, the amplification of test radiation arises in a certain range of frequency offsets A instead of the absorption, and the energy transfers from a strong wave to a weak one. In this paper we study the problem which appears from the above situation, when the intensity of test radiation increases. Such an increase leads to new maxima in absorption spectra of test radiation at frequencies A = i n = 2, 3 4 . . . which are additional to the main maxima at n R A = where R the Rabi frequency. These new resonances were observed by Bonch-Bruevich, Vartanyan, and Chigir in 19792 and cal led the subradiat ive structure. We have the following simple approximate expression for R obtained in the case of interaction with two fields: Q =d(?+E2)1"2/h. (1) R 0 1 There are two essential effects in the described situation: the saturation of absorption and the nonlinear interference effect. The last causes the redistribution of an absorbed energy between radiation components, the negative absorption (amplification) without population inversion, and the multiphoton parametric resonances at difference frequencies. The laser generation on the base7of the negative absorption without population inversion was obtained in 1989. The following problems arise from the facts reviewed above: 1. The calculation of absorption coefficients for individual components of a strong polychromatic radiation with an equidistant spectrum. 2. Determining of a generalized Rabi frequency and verification of the simple formula A = In for maxima of resonances. n R The aim of this paper is to solve these problems.

Proceedings of SPIE, the International Society for Optical Engineering/Proceedings of SPIEJul 1, 19921 citation

Emission of radiation by a resonance medium excited with a variable superluminal velocity

Rostislav M. Arkhipov, A. V. Pakhomov

Specific properties of the radiation emitted by a spatially modulated resonance medium excited by an ultrashort light pulse propagating through the medium at a variable superluminal velocity are analyzed. In so doing, frequencies different from that of the resonance transition of the medium may appear in the emission spectrum. It is demonstrated that, in contrast to an earlier studied case of medium excitation at constant velocity, variation of the excitation velocity leads to generation of a spectral continuum, the boundaries of which are determined by the range of variation of the medium-excitation velocity.

Optics and SpectroscopyMay 1, 20172 citations

Macroscopic properties of materials from stimulated emission and absorption

W.S.C. Chang

All optical oscillators and amplifiers can be analyzed as an electromagnetic structure, such as a cavity or a transmission line, which contains an amplifying medium. The operating characteristics of lasers are governed by both the electromagnetic properties of the structures and the properties of the amplifying medium. Stimulated emission and absorption of radiation from energy states are the physical basis of amplification in all laser materials. In order to study lasers, it is necessary to understand the energy levels of the amplifying medium and the stimulated transitions involving them. Quantum mechanical analysis of the energy states and the stimulated emission and absorption is presented in most books on lasers. However, quantum mechanical analyses cover only the analysis of individual atoms. We need to relate the effects of the quantum mechanical interactions to the macroscopic properties of the materials so that properties of the lasers may be analyzed. Therefore, the macroscopic susceptibility of materials related to stimulated emission and absorption is the focus of discussion in this chapter. It is not the purpose of this book to teach quantum mechanics. There are already many excellent books on this topic. The readers are assumed to have a fundamental knowledge of quantum mechanics. However, it is necessary first to review some of the major steps in order to understand precisely the notation used and the meaning of the results. This is presented in Section 5.1.

Cambridge University Press eBooksJan 20, 20050 citations

On the nature of the Mossbauer effect

A. V. Kirichok, Volodymyr M. Kuklin, Anatolij G. Zagorodny

The spectrum of electromagnetic waves emitted by an oscillator trapped in an external potential well is studied. It is assumed that the natural frequency of the oscillator is much greater than the frequency of oscillations in the potential well. We consider the quantum model of emission with regard to the recoil effect. The highest intensity of the absorption and emission lines is observed on the natural frequency of the oscillator when the recoil energy is equal to the energy of the quantum of low-frequency (LF) oscillations in the potential well. A certain decrease in the amplitude of the emission and absorption lines is noted caused by the oscillations of the potential well due to, for example, the presence of the phonon spectrum. The relaxation times of the oscillator LF motion in the potential well, resulted from the phonon emission, are estimated. It is concluded that these processes have no influence on the observed features of the emission and absorption of high-frequency photons. This model can be applied to description of the emission and absorption of gamma rays in the crystal structures even in the presence of the phonon spectrum on condition that the relaxation time of the LF movements in the potential well is greater than the lifetime of the HF oscillator.

arXiv:1701.06223Jan 22, 20170 citations