ABSTRACT
We combine highly sensitive intracavity absorption spectroscopy in a multimode laser with external photoacoustic detection, providing high detectivity. Photoacoustic measurements of the intracavity iodine concentration in a Rhodamine 6G laser are compared with simultaneous spectral recordings. They demonstrate slightly improved overall sensitivity and a greatly enhanced dynamic range of 5 orders of magnitude that may be shifted along the absolute scale of absorber density.
ABSTRACT
A broadband Nd(3+)-doped fiber laser has been operated in an external cavity by pumping with an Ar(+)-ion laser. The emission spectrum of the fiber laser shows high sensitivity to intracavity absorption. The equivalent absorber path length is 15 km; with a loss-reduced setup that includes pumping by a diode laser this path length is 150 km. The spectrum of atmospheric absorption in the range from 1.065 to 1.145 microm has been recorded by stepwise tuning of the 0.3-nm-wide laser emission band by an intracavity prism.
