Abstract

When using a laser source for frequency domain spectroscopy, source linewidth invariably limits spectral resolution. Consequently, high-resolution spectroscopy generally requires frequency stabilized single frequency lasers. In extending the theory of frequency modulation absorption spectroscopy to the case of multimode dye lasers¹ we noticed that when both laser mode spacing and modulation frequency are small compared to absorber linewidth, the absorption spectrum measured by such a source could show features which were much sharper than the effective laser linewidth. We have now been able to demonstrate this effect using a coherent 599-01 dye laser tuned only with a biréfringent plate. We will present some experimental results on atomic sodium and molecular iodine absorption. We will also discuss the high-resolution tuning and frequency stability properties of the dye laser itself.

© 1990 Optical Society of America