Time delay in CdS laser pumped by an electron beam

Time delays of up to 500 nsec were observed in the stimulated emission of Cd-rich CdS crystals at 80° K pumped by an electron beam. The delay decreased with increase of excitation and the memory effect of the first pulse was observed for lasing during the second pulse when two separated electron-beam pulses (double pulse) were applied to the sample.The results were compared with the trapping model proposed by Fenner in which traps provide a large amount of optical absorption and the expression for the delay in the case of electron-beam pumping was derived. The experimental results were well explained by this model.