Influence of saturation absorption on the sensitivity of intracavity spectroscopy

An experimental study was made of the dependence of the sensitivity of intracavity laser spectroscopy on the excess pump power above the threshold. The investigation was carried out on Na and H₂O vapors using a cw dye laser. The observed dependence of the sensitivity in the case of the Na vapor was attributed to the saturation of absorption in the laser radiation field. The published reports of the saturation of the sensitivity of the intracavity method in a time of ~100 nsec was attributed to the saturation of absorption and not to spatial effects.