Laser Spectroscopy

Abstract

Practically every method of multiple interaction of light with a test object considered so far enhances the sensitivity to a given low optical loss via the enhanced measured signal owing to an increased number of light interactions. Among other phenomena, generation of laser light in any active medium with a low gain factor is stipulated by the very same multiple reflections in an open laser resonator with a high quality factor. Since the power and energy parameters of stimulated emission are defined by correlations of laser gain and attenuation, corresponding to every pass via that open laser resonator, one can expect high sensitivity of laser emission to the presence in its resonant cavity of any embedded optical loss. Such excessive sensitivity can be manifested via changes of the laser power or energy output in a broad spectral domain of its active medium amplification or as spectrally selective optical losses in narrow spectral intervals.