Very Short Far Infrared Pulses from Optically Pumped CH3OH/D, Chooh and CH3F Lasers using an Eq-Switched CO2 Laser as a Pump Source

摘要

This paper describes the generation of far infrared pulses with a risetime of 10^{-8s from optically pumped CH₃OH/D, CHOOH and CH₃F lasers using a Q-switched current pulsed CO₂ laser as a pump source. The pump source consists of a conventional tunable low pressure (20 Torr) CO₂ laser which is Q-switched by a rotating mirror mounted on an air-driven spindle. Discharge current pulses up to 200 mA and 100-300 μs duration are produced and synchronized to the Q-switch by a trigger pulse from the rotating mirror. Due to the high discharge current, output powers are increased by at least a factor 5 with respect to Q-switched pulses from a d.c. current mode (20 mA). This leads to kW peak power pulses even at transitions such as 9P38, 9P6 and 9R6 which are especially important for pumping CH₃OH and CH₃OD. The pump pulses are focussed by an f = 50 cm mirror onto the 1 mm incoupling hole of the FIR cavity, which consists of a 1 m long 13 mm diameter quartz tube and two 25 mm diameter flat mirrors.}