Investigation of a multielement electron-beam-pumped semiconductor laser with an external mirror

An experimental investigation was made of a multielement semiconductor laser pumped longitudinally by an electron beam. When the inequality d<(2Lλ)^1/2(d is the distance between the laser elements, L is the distance to the external mirror, and λ is the stimulated emission wavelength) was satisfied, mode-locked operation was possible and this reduced the angular divergence of the ouput radiation. Amplified spontaneous radiation, reflected from an external mirror, had a considerable influence on the laser operation: It gave rise to a complex field pattern in the far zone and reduced the coherent output power until the laser action stopped altogether. The influence of the amplified spontaneous radiation increased with increasing total size of the multielement system.