Spectral dynamics of a multimode Co:MgF 2 laser with intracavity absorption

Abstract

Intracavity laser spectroscopy (ICLS)2 is an absorption spectroscopy technique in which an absorbing species is placedinside the cavity of a broad-band laser. The emission spectrum of a laser is extremely sensitive to small wavelength-dependent intracavity losses, if the width of absorption line is smaller than the homogeneous bandwidth of the lasergain. Therefore even minute quantities of an intracavity absorber lead to spectral holes in the output laser spectrum.The spectral extinction of laser emission is governed by the modified Lambert-Beer law. If we define the laser intensityat a particular absorption line frequency o as I(a) and the laser intensity just outside the absorption line as 4, then forany time of laser generation t this law can be written in the formI(o)/Io=exp(-k(o)ctgLa/Lc), (1)where k(e)) is the absorption coefficient ofthe line, La 5 the physical length ofthe intracavity absorption cell, L is the totaloptical cavity length and c is the speed of light. It follows from (1) that the effective absorption path length Leff