We describe a modulated-gain spectrometer consisting of two single-mode cw dye lasers and a cw optically pumped molecular laser with which it is possible to examine molecular energy levels near dissociation limits. These neardissociation levels are normally Franck-Condon inaccessible from thermally populated levels. The Na2 A 1Σu+ υ = 43–105 and B 1IIu υ = 24–33 levels are observed for the first reported time by modulated-gain spectroscopy (MGS). The principles of operation of the MGS spectrometer are presented along with examples of several types of MGS effects.
© 1985 Optical Society of America
S. Churassy, G. K. Chawla, and R. W. Field, "Modulated-gain spectrometer," J. Opt. Soc. Am. B 2, 1929-1933 (1985)