Certain aspects of the spectral kinetic characteristics of a ruby sweep generator

Abstract

Interest in lasers in which the frequency may be varied in the course of generation (sweep generators) arises chiefly from the possibility of using these in express spectroscopy. As regards their fundamental characteristics, optical sweep generators may be divided into two classes: those having adiabatic frequency adjustment and those having nonadiabatic frequency adjustment. The first class includes generators with a variable resonator length [i]. These provide smooth adjustment of the radiation frequency by virtue of the Doppler effect at the mirrors, and hence their spectral resolution is only limited by the "instantaneous" width of the spectrum of the generated mode. In such generators, however, it is technically difficult to ensure a wide range of frequency adjustment. The second class includes generators with a dispersive resonator of constant length. The generation frequency is adjusted by varying the characteristics of the dispersive element in time [2]. In such generators it is possible to vary the frequency over the whole amplification line, but this adjustment occurs in sharp jumps with a step at least equal to the intermode interval. In certain cases [3, 4] the frequency jumps are several times greater than the intermode interval, which reduces the resolving power when such generators are used. The aim of the present investigation was to discover the way in which this parameter was influenced by such an important factor as the spatial inhomogeneity of inversion (which under ordinary conditions governs the kinetics of the spectrum [5]) and also by the elements of the optical system used for increasing the resolving power of a ruby sweep generator with a'resonator of constant length.