Multilayer GaAs injection laser

Experimental data are presented for multijunction GaAs lasers made by vapor-phase epitaxial growth in the form of structures. The overall thickness of the four inside layers was 5 microns for the multilayer material for which experimental data are given. The diodes made from this material exhibited current-controlled negative-resistance characteristics. The emitted output beams of the multilayer lasers were extremely narrow, with the beam diverging only 0.5 degree in the direction transverse to the junction planes. The corresponding near-field patterns for these lasers have, in addition to the expected bright laser regions, almost fifty lines spaced about 1 micron apart and almost equally bright. The current thresholds at 77°K for the multijunction lasers are three to four times higher than single-junction laser thresholds and the incremental output quantum efficiencies of these lasers were more than unity, 1.1.