Far-field radiation pattern of the low-threshold room-temperature electron-beam and optical pumped green semiconductor lasers

Far-field radiation pattern of the low-threshold room-temperature pulsed green semiconductor lasers was studied. ZnSe-based quantum wells and "quantum disc" structures were grown by molecular beam epitaxy. Transverse geometry of pumping was used. The N₂-laser and cathode-ray-tube with 10-25 kV accelerating voltage were applied as the pumping sources. The far-field pattern reveals a strong asymmetrical shape. Laser beam angular divergence is 30-40 degrees in the plane involving the pumping beam and laser cavity axes, and is 3-6 degrees in the plane of semiconductor structure. In this plane the increase of the divergence from 3 up to 6 degrees with increase of the excited area size from ∼ 0.01 up to ∼ 0.2 mm was observed. At the same time, the far-field changes from one-lobe form to many-lobe one. The output pulse power up to 9 W per one facet for different transversal modes in near and far fields were calculated and compared with the experimental results.