Kinetics of formation of the CO2 molecule distributions over the vibrational-rotational levels in the active medium of a waveguide CO2 laser

Self-radiation of an absorbing medium induced by a fast frequency-tuning laser

“…The semiclassical description [4] is applied: the radiation field is treated classically and the medium is considered as a number of non-interacting two-level quantum oscillators with bulk density N. It is assumed that the light beam is collinear with a linear polarization, and the moments of transition in quantum systems are oriented in space in the direction of the polarization of the incident radiation. The method of calculation of the electric field is based on the simultaneous solution of the classical wave equation and the von Neumann equation for a twolevel system.…”

“…The method of calculation of the electric field is based on the simultaneous solution of the classical wave equation and the von Neumann equation for a twolevel system. In [4] the following expression was obtained for the complex amplitude of the electric field E(t, z) at the exit of the cell of length z:…”

“…The development of frequency-tunable lasers has led to new approaches in the study of the coherent effects. The coherent interaction of fast-tuning laser radiation with an absorbing medium without any additional fields was first studied in [4] (see also) [5]. Linearly polarized and frequency modulated radiation of the injection diode laser with wavelength λ ≈ 4.2 mkm was used with a tuning rate μ.…”

“…The model of this phenomenon was provided and showed qualitative agreement with the experiment. There were no detailed quantitative comparisons in [4] since the rate of the frequency tuning of 'classical' diode lasers and the detection speed of fast signals in the IR region were limited. Later the development of fast-tuning quantum cascade lasers and modern techniques of spectra recording stimulated the new studies of these effects [6][7][8][9][10].…”

Vibrational cooling of the active medium of a laser by the intra-cavity radiation flux

“…The experimental lay-out is shown schematically in figure 1. The components of the spectrometer are described elsewhere [12][13][14], the main change being the provision of side windows on the discharge tube to allow transverse probing. The measurements are thus values averaged over the radial temperature distribution, which was found to be essentially flat due to efficient turbulent mixing [11].…”