Dye ring laser with unidirectional generation and a narrow emission spectrum locked to atomic absorption lines

Abstract

When laser radiation is used for resonance interactions with matter and for analytic applications, a well-reproducible narrow laser spectrum which coincides with selected absorption lines of the material under inspection is required. Such a spectrum can be obtained with the aid of phase-polarized resonance techniques of frequency selection. The general principles of the techniques and a first successful frequency selection made with the techniques (in gas lasers) have been described in [i, 2]. One of the versions of phase-polarized resonance selection has been earlier used [3] for the spectral selection of the radiation of nonlaser sources. The later attempt of [4] to tune with the technique of [3] a narrow generation line of a dye laser to the center of the absorption line contour of sodium was unsuccessful. The generation spectrum was successfully narrowed and locked to the atomic absorption lines with phase-polarized resonance selection in linear continuous and pulsed dye lasers of [5-7] and [8-9], respectively. In [5-7], as well as in [3], two crossed polarizers were employed. The absorbing medium ina longitudinal magnetic field was placed between the polarizers. In this case, the Faraday rotation of the plane of polarization of the radiation must reach the value ~/2 in the absorbing medium. The authors of [8, 9] have used versions of the phase-polarized resonance selection of [i, 2]; the versions do not require large values of circular and linear birefringence. In [5-8], generation was obtained in a single longitudinal mode in the center of the absorption line contour; the authors of [9] used linear birefringence of the absorbing medium and obtained generation at a frequency tuned away from the center of the line contour.