Continuous-Wave Dye Lasers

Abstract

The operation of the continuous-wave (cw) dye laser is based upon the same molecular states as that of pulsed lasers. However, some loss mechanisms that are relatively unimportant in the pulsed laser tend to dominate the performance of the cw laser. For example, the accumulation of molecules in the triplet state plays a major role in determining the efficiency of the cw laser, whereas the triplet state is relatively unimportant in pulsed lasers. Also, optical inhomogeneities produced in the active medium by heating resulting from excitation must be carefully controlled for the laser to operate continuously. Excitation sources for pulsed lasers are generally capable of producing intensities greatly in excess of that required to reach laser threshold. Pump sources for cw lasers, on the other hand, are often marginal. For these reasons, the efficient operation of a cw dye laser requires careful design and construction to minimize extraneous optical losses. The mechanical and optical tolerances are generally much more severe than those for pulsed dye lasers. In this chapter the analysis and design of cw dye lasers will be considered. Tuning systems will be discussed and the characteristics of some experimental cw laser systems reviewed.