Dynamics of the intracavity absorption in the spectrum of a Co:MgF2 laser emitting for up to 1 ms

The dynamics of the spectral dips, observed in detection of weak absorption lines by intracavity laser spectroscopy with a Co:MgF₂ laser, was investigated. When the pumping rate exceeds the threshold by factors of 2.6 and 1.4, the intracavity absorption increases linearly with increase in the duration of lasing to 0.5 and 1 ms, respectively. A deviation from linearity is observed for longer times. This ensures a sensitivity sufficient for measurement of the line absorption coefficient down to 3 × 10^–9 cm ¹ in the 1.6 — 2.5 μm spectral range of laser emission.