Divergence of the output radiation of electron-beam-pumped "radiating mirror" lasers

An investigation was made of the divergence of the radiation emitted by an electron-beam-pumped GaAs laser. The laser was of the "radiating mirror" type and the divergence was determined as a function of the distance L from an external mirror. The divergence was 7' for L = 28 mm, which corresponded to the excitation of the principal transverse mode. The width of the longitudinal modes decreased with increasing L: For L = 22 mm the mode width was Δλ ≤ 0.05 Å.