This thesis is in two parts. Part A is about the study of the LD-4 Regenerator and Part B is about Lasing Action. Both are essential for the completion of Stephen Brown's Master of Engineering Degree. / <p>The switching mechanism of the LD-4 regenerator is studied by applying triangular signals with variable slope and phasing with respect to the sampling pulse in order to investigate their effect on the output signal voltage. Experimental results are obtained in the form of finite sampling crosshairs. These represent the family of input signals that produce all output between the 0 and 1 state. In effect they characterize PST input signals at the N^(th) regenerator to the eventual PST signals at the N+1^(th) regenerator input. </p><p> An attempt is a 1 so made to correlate the experimenta 1 data with either a constant voltage or constant charge sensitivity model in order to understand the mechanism of sampling. </p><p>Results of a detailed investigation of the time-dependence of the stimulated emission from electron-beam pumped CdS platelets are reported. Unlike lower threshold platelets previously reported (1), the platelet examined here exhibits rapid tuning with time of the stimulated emission to longer wavelength. The rate of this frequency tuning canpares favourably with the value reported by Shewchun et al (2) for CdS crystals many times thicker and with a higher threshold than the one measured in this report. Furthermore, there is a temporal variation of the angular position of the spatial mode. This temporal variation or angular tuning rate was compared with angular tuning data reported for GaAs and CdSe as well as with the theory that predicts such tuning in these crystals (3). </p> / Thesis / Master of Engineering (ME)