Variation of the temporal delay to threshold in nanosecond-tunable dye lasers

We present an experimental study, complemented by numerical simulations, of the delay from the peak of the pump pulse to threshold of the dye laser pulse as a function of the selected wavelength. Delay variations of up to 0.2 nsec/nm were observed in Rhodamine dyes pumped by a N(2) laser. We conclude that the variations are intrinsic to the gain-loss characteristics and that excited-state singlet absorption can play a significant role.