ENHANCEMENT OF THE SENSITIVITY OF A MULTIMODE DYE-LASER TO INTRACAVITY ABSORPTION

The sensitivity of the emission spectrum of multimode cw dye lasers to intracavity absorption is limited by nonlinear coupling of the laser modes inside the dye. We demonstrate that the cross section of this coupling is reduced by increasing the geometrical length of the laser cavity. The emission spectrum of a Rh6G laser with a 1.9 m cavity shows at least ten times higher sensitivity to intracavity absorption than what was reported before. The laser spectrum approaches its stationary shape 100 ms after the onset of the laser oscillation. Atmospheric lines with absorption coefficients of some 10(-10) cm-1 have been recorded in the 590 nm range.