Photon loss and gain in CdS electron-beam-pumped lasers

Photon loss coefficients in the active and passive regions of CdS electron-beam-pumped lasers were measured by a variable-length masking technique and found to be 140 and 230 cm^-1, respectively. The results show there is little saturable absorption in Cd-rich CdS, and their marked difference from GaAs demonstrates that the absorption mechanisms are different in the two materials. A net gain of 45 cm^-1was measured at an excitation of 8.2 kW/cm²using a nonresonant crystal configuration. This corresponds to an efficiency 700 times greater than that for optical excitation.