Single-mode lasers (1050 nm) of mesa-stripe design based on an AlGaAs/GaAs heterostructure with an ultra-narrow waveguide

The emission characteristics of single-mode lasers based on an AlGaAs/GaAs heterostructure with an ultra-narrow waveguide are studied. It is shown that using an ultra-narrow waveguide (100 nm) and thin (70 nm) wide-gap barriers at the waveguide/cladding interface makes narrower the vertical divergence of far-field emission. The lateral and vertical divergences are 5$^\circ$ and 18.5$^\circ$, respectively, for the narrow-stripe (5.1 $\mu$m) single-mode lasers developed in the study. The lasers demonstrate efficient single-mode operation up to a power of 200 mW. Raising the current further gives rise to higher order modes, the maximum optical power in continuous-wave lasing being limited to 550 mW by overheating. Passing to the pulsed operation mode (pulse width 200 ns) makes it possible to raise the maximum peak optical power to 1500 mW.