Single and Double Mode-Locked Ring Dye Lasers; Theory and Experiment

Abstract

A passively modelocked ring dye laser has been shown[1] to produce optical pulses in the femtosecond regime. We have undertaken experimental and theoretical investigations of this configuration with both single and double modelocked[2] operation. In the set up shown in Fig.1, Rh6G was used as the gain dye, with DODCI or cresyl violet as the saturable absorber in the single and double modelocked lasers respectively. The Rh6G was pumped by a cw argon laser. At certain positions of the dye jets and critical tuning (615nm), narrow modelocked pulses were observed. At other tunings with pulse widths of the order of a fraction of the roundtrip time are formed. These pulses are very stable with respect to pump power. The exact behavior changes with the relative positions of the gain and absorber dyes. A computer program was written to analyze the system and provide a better understanding of the pulse formation.