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Title: Gain dynamics in the active medium of a pulsed e-beam sustained discharge CO laser: theory and experiment

Abstract

The small-signal gain (SSG) dynamics is studied experimentally and theoretically in the active medium of a pulsed e-beam sustained discharge CO laser in a broad range of vibrational transitions, various compositions and densities of the active medium, as well as various positions of a small-aperture probe laser beam in the gas-discharge region. The results of measurements are compared with theoretical calculations based on a spatially homogeneous CO laser model taking into account the multiquantum VV exchange processes. The sensitivity of the SSG dynamics to variations in the active medium and pump parameters is studied. Good agreement is demonstrated between theoretical and experimental data on the SSG dynamics obtained by using corrected values of local energy input in the calculations. (lasers)

Authors:
; ; ; ; ; ;  [1]; ; ; ;  [2]
  1. P.N. Lebedev Physics Institute, Russian Academy of Sciences, Moscow (Russian Federation)
  2. State Research Center of Russian Federation 'Troitsk Institute for Innovation and Fusion Research', Troitsk, Moscow Region (Russian Federation)
Publication Date:
OSTI Identifier:
21470865
Resource Type:
Journal Article
Resource Relation:
Journal Name: Quantum Electronics (Woodbury, N.Y.); Journal Volume: 35; Journal Issue: 12; Other Information: DOI: 10.1070/QE2005v035n12ABEH008963
Country of Publication:
United States
Language:
English
Subject:
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; APERTURES; CARBON MONOXIDE; DENSITY; ELECTRIC DISCHARGES; ELECTRON BEAMS; EXPERIMENTAL DATA; GAIN; LASERS; PROBES; PUMPING; SENSITIVITY; SIGNALS; THEORETICAL DATA; VARIATIONS; AMPLIFICATION; BEAMS; CARBON COMPOUNDS; CARBON OXIDES; CHALCOGENIDES; DATA; INFORMATION; LEPTON BEAMS; NUMERICAL DATA; OPENINGS; OXIDES; OXYGEN COMPOUNDS; PARTICLE BEAMS; PHYSICAL PROPERTIES

Citation Formats

Vetoshkin, S V, Ionin, Andrei A, Klimachev, Yu M, Kozlov, A Yu, Kotkov, A A, Seleznev, L V, Sinitsyn, D V, Kurnosov, A K, Napartovich, A P, Rulev, O A, and Shnyrev, S L. Gain dynamics in the active medium of a pulsed e-beam sustained discharge CO laser: theory and experiment. United States: N. p., 2005. Web. doi:10.1070/QE2005V035N12ABEH008963.
Vetoshkin, S V, Ionin, Andrei A, Klimachev, Yu M, Kozlov, A Yu, Kotkov, A A, Seleznev, L V, Sinitsyn, D V, Kurnosov, A K, Napartovich, A P, Rulev, O A, & Shnyrev, S L. Gain dynamics in the active medium of a pulsed e-beam sustained discharge CO laser: theory and experiment. United States. doi:10.1070/QE2005V035N12ABEH008963.
Vetoshkin, S V, Ionin, Andrei A, Klimachev, Yu M, Kozlov, A Yu, Kotkov, A A, Seleznev, L V, Sinitsyn, D V, Kurnosov, A K, Napartovich, A P, Rulev, O A, and Shnyrev, S L. Sat . "Gain dynamics in the active medium of a pulsed e-beam sustained discharge CO laser: theory and experiment". United States. doi:10.1070/QE2005V035N12ABEH008963.
@article{osti_21470865,
title = {Gain dynamics in the active medium of a pulsed e-beam sustained discharge CO laser: theory and experiment},
author = {Vetoshkin, S V and Ionin, Andrei A and Klimachev, Yu M and Kozlov, A Yu and Kotkov, A A and Seleznev, L V and Sinitsyn, D V and Kurnosov, A K and Napartovich, A P and Rulev, O A and Shnyrev, S L},
abstractNote = {The small-signal gain (SSG) dynamics is studied experimentally and theoretically in the active medium of a pulsed e-beam sustained discharge CO laser in a broad range of vibrational transitions, various compositions and densities of the active medium, as well as various positions of a small-aperture probe laser beam in the gas-discharge region. The results of measurements are compared with theoretical calculations based on a spatially homogeneous CO laser model taking into account the multiquantum VV exchange processes. The sensitivity of the SSG dynamics to variations in the active medium and pump parameters is studied. Good agreement is demonstrated between theoretical and experimental data on the SSG dynamics obtained by using corrected values of local energy input in the calculations. (lasers)},
doi = {10.1070/QE2005V035N12ABEH008963},
journal = {Quantum Electronics (Woodbury, N.Y.)},
number = 12,
volume = 35,
place = {United States},
year = {Sat Dec 31 00:00:00 EST 2005},
month = {Sat Dec 31 00:00:00 EST 2005}
}
  • The method for measuring the rate constants of the VV' exchange between CO and O{sub 2} molecules is developed. The method is based on a comparison of the measured and numerically calculated small-signal-gain (SSG) dynamics in the active medium of a pulsed electron-beam-controlled cryogenic CO laser. The SSG dynamics was measured in CO-He-O{sub 2} mixtures with the fixed CO:He = 1:4 ratio by varying the oxygen content from 0 to 4%. The SSG dynamics was measured by probing the active medium of the pulsed CO laser by a beam from a tunable cw CO laser. The mathematical model of themore » CO laser takes into account the influence of oxygen on energy exchange processes. The parameters of the analytic approximation for constants of the near-resonance VV' exchange CO(v)+O{sub 2}(u=0) {yields} CO(v-1)+O{sub 2}(u=1) are determined by the developed method for quantum vibrational numbers v = 18-24. In particular, the rate constant for v = 20 is (3.1{+-}0.5)x10{sup -12} cm{sup 3} s{sup -1} at the gas temperature of 150 K. The extrapolation of the obtained analytic expression for rate constants in gases at room temperature gives the reasonable agreement with the measurements performed earlier for v = 12 and 13. (active media. lasers)« less
  • The time dependences of the gain of vibrational-rotational lines of the CO molecule were investigated experimentally for the first time in the case of pulsed electron-beam-controlled excitation by ionization of carbon monoxide cooled to cryogenic temperatures. The Patel formula was used to calculate the temperature rise of the active medium during the pumping process. The efficiency of the vibrational excitation of CO for E/N = 2--4 kVxcm/sup -1/xamagat/sup -1/ was estimated to be 70--80%.
  • Typical excitation conditions in a pulsed electron-beam-controlled CO laser were studied and the times for attaining a fixed unsaturated absorption level due to different vibrational transitions of the CO molecule were determined. These times were compared with those calculated by varying the values of the short- and long-range components of the vibrational--vibrational (VV) exchange constant. The values of these constants were then refined.
  • Numerical simulation is used as the basis of an analysis of nonlinear optical properties of the active medium in intracavity four-wave mixing of the radiation of a pulsed electron-beam-controlled discharge CO{sub 2} laser on saturated-gain and refractive-index diffraction gratings. The reflection coefficient of the phase-conjugated signal is determined for various cavity Q-factors, specific input energies, and pressures of the laser-active mixture. A comparison is made of the theoretical and experimental results. It is found that the rate of formation of amplitude gratings is governed primarily by the initial population inversion and by the intensities of the interacting waves. It ismore » shown that transient phase gratings make the dominant contribution to the phase-conjugate reflection coefficient at high pressures of the mixture. (nonlinear optical phenomena)« less
  • An experimental investigation was made of phase conjugation in the course of intracavity degenerate four-wave mixing of radiation in the active medium of a pulsed electron-beam-controlled discharge CO{sub 2} laser generating long pulses. An analysis was carried out of the dependences of the energy and temporal characteristics of a phase-conjugated signal on the specific input energy deposited in the electron-beam-controlled discharge, on the Q-factor of the laser cavity, on the composition and pressure of the laser-active mixture, on the angle of interaction and optical delay between the probe and reference waves, on the ratio of the intensities of these twomore » waves, and on the polarisation and spectral composition of laser radiation. The energy reflection coefficient of the phase-conjugated signal increased with increase in the input energy and with reduction in the probe wave intensity. An increase in the proportion of nitrogen and a reduction in the proportion of helium in the laser-active mixture increased the reflection coefficient and gave rise to a specific profile of the phase-conjugated signal with two maxima, attributed to amplitude and phase nonlinearities of the active medium. An increase in the specific input energy and of the cavity Q-factor reduced the response time of the phase-conjugate signal. (nonlinear optical phenomena and devices)« less