High-Power 2 $\mu {\rm m}$ Diode Lasers With Asymmetric Waveguide

Asymmetric laser heterostructure was developed to improve beam properties of GaSb-based diode lasers emitting near 2 μm. It was demonstrated that the lasers with narrow waveguide and asymmetric claddings could have fast axis beam divergence below 40°. High-power diode lasers with 100-μm-wide output aperture generate more than 1.5 W of continuous wave (CW) output power in a beam with fast axis beam divergence of 50°. Power conversion efficiency of the 2 μm emitters peaked at 28%. CW threshold current density of 85 A/cm
²
was achieved at 20°C. Passively cooled 18-element linear laser arrays generated more than 10 W of CW power at 50 A. Above 3 W of CW power was obtained from 7-fiber bundle at 7 A.