The use of one or more intracavity etalons for the selection of a single longitudinal mode of a cw dye laser is described. The interaction of the etalon with the main cavity and the broadband tuning elements is discussed and criteria for selecting the proper etalon free spectral range and mirror reflectivity are given. Synchronization of the etalon and main cavity tuning to obtain large deviation frequency scans is discussed. Factors influencing the stability and ultimate linewidth are briefly mentioned.
John P. Goldsborough,
"Scanning Single Frequency CW Dye Laser Techniques for High-Resolution Spectroscopy," Optical Engineering 13(6), 136523 (1 December 1974). https://doi.org/10.1117/12.7978718