Field-atom interaction during four-wave mixing processes in vibronic and Raman lasers

Abstract

Recently, a new approach to cool optically pumped solid-state lasers by converting the lattice heat into radiation was presented [Laser Phys.18, 430 (2008)]. It relies on a stimulated radiative process occurring in the laser host material. The internal heat gets partially converted through a four-wave mixing process into a radiating optical field. By adopting a Lorentz oscillator model for the field-atom interaction in the laser host, we identified a shortcut to treat the heating and cooling mechanisms going together with the Stokes and anti-Stokes radiation involved in the four-wave mixing. An energy balance between these mechanisms is derived from the differential equation for the material excitation. This balance will ultimately determine the crystal steady-state temperature. This analysis is the first step towards practical engineering implementations of the optical cooling principle for important new laser systems such as the silicon Raman laser and the Cr-ZnSe laser for the mid-IR.