Knowledge Bank

Intracavity absorption spectroscopy with dye lasers has been used to detect absorptions with optical densities $102$ to $105$ weaker than can be detected with ordinary spectrometers. We have now shown that using a laser cavity which supports many high order transverse modes it is possible to enhance a spatial as well as a spectral variation in absorption. We can detect weakly absorbing samples that cover only a small fraction of the intracavity beam. This technique has some practical applications and can be used to increase the sensitivity of the intracavity technique.