Kinetics of transition through lasing threshold

Vladimir P Bykov

S. M. Dutra, Jorrit Visser, Gerard Nienhuis +1 more

Chi‐Wai Chow, F. Jahnke, Christopher Gies

A quantum-optical model is applied to address the question of criteria for lasing in a threshold less laser where the intensity jump, customarily used to indicate transition to lasing, is missing.

Valentyn I. Prokhorenko, Eugene A. Tikhonov

An image-converter streak camera with picosecond time resolution was used in a study of the kinetics of formation of pulses in a traveling-wave laser in which molecular dye solutions were subjected to two-photon optical pumping. An analytic expression was obtained for the lasing threshold of a nonresonator traveling-wave laser in the case of pulsed (τp τe) and quasicontinuous (τp > τe) pumping. Satisfactory agreement was obtained between the calculated and experimental lasing threshold. The kinetics of the compression of output pulses, determined as a function of the pump radiation intensity, was described by rate equations. At pumping rates up to 10 times the threshold a qualitative agreement between the experimental and calculated results was obtained employing a two-band energy model of the dye with a short (compared with the duration of the pump pulses τp) vibrational relaxation time τe. At rates of excitation well above the threshold the kinetics of compression and delay changed, and the output pulses were split into two components, which was interpreted (in the specific case of rhodamine 6G) using a four-band energy scheme. A practical conclusion of this investigation was in the form of recommendations on the use of the proposed approach as a simple method for generating high-intensity single picosecond superradiance pulses of duration τsr with frequency up-con version and a compression coefficient τp/τsr ~ 10.

Yoshimasa Isawa

Sergey V. Gaponenko, Hilmi Volkan Demir