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Soviet Journal of Quantum Electronics

Theory of rotational depolarization of laser radiation emitted by dye solutions

V. A. Gaisenok, V. V. Gruzinskii, George G. Krylov

Published Jul 31, 1988• 0 citations
Publisher

Abstract

The rate equations for the populations of states and the intracavity radiative transfer equations are used, in an analytic description of rotational depolarization of the output radiation of cw dye-solution lasers under strong saturation conditions. Expressions are obtained for the energy and the degree of polarization of radiation. It is shown that under such conditions the degree of polarization depends linearly on the velocity of Brownian rotation of molecules.

DOI
10.1070/qe1988v018n07abeh012330

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The rate equations for the populations of states and the intracavity radiative transfer equations are used, in an analytic description of rotational depolarization of the output radiation of cw dye-solution lasers under strong saturation conditions. Expressions are obtained for the energy and the degree of polarization of radiation. It is shown that under such conditions the degree of polarization depends linearly on the velocity of Brownian rotation of molecules.
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We have developed a self-consistent description, based on the semiclassical radiation theory of the propagation of a light pulse in a dye medium. The multilevel nature of the energy bands of a dye molecule and the solvent cage effect in a solution are taken into account. In the case of light pulses whose duration is much shorter than the solvent-solute relaxation time but much longer than the time of atomic phase memory, the latter being of the order of ${10}^{\ensuremath{-}12}$ sec for dyes, we solve the coupled system of equations for the field and the medium by the perturbation procedure. The hole-burning effect is incorporated into the solution in a natural manner. This is especially clear in the direct transition approximation where all the intermediate transitions are neglected. A recent idea of pulse superposition, consisting in storing the energy of a pulse in the form of population inversion followed by stimulated emission triggered by another pulse, is further discussed. Contrary to the orginal model developed by one of us (S.L.C.), we show that no cw pumping is required. The feasibility of the pulse superposition is supported by some experimental results obtained by sending a train of 10-psec pulses through a glycerine solution of oxazine 1 perchlorate.