Standing waves and single-mode room-temperature laser emission from electron-beam-pumped cadmium sulfide

A thin crystal of CdS produced well-defined standing waves in spontaneous light emission when end-pumped by an electron beam at excitation levels six orders of magnitude below that necessary for stimulated emission. Single-frequency mode output was observed in stimulated emission at 5205 Å at room temperature. At 77°K and at excitation levels well above threshold, laser emission was observed to occur continuously over a spectral range of nearly 200 Å, from 4960 to 5150 Å.