Filamentation-Free Broad-Area Laser Design for Efficient Coupling to Single-Mode Fiber

Although the quest for high-power, diffraction-limited, semiconductor lasers has arguably met with limited success, the drive for higher brightness diode lasers continues, driven by fiber laser systems. Using tailored refractive-index and injection-current profiles, broad-area laser beam propagation method simulations predict simultaneous suppression of free-carrier-induced self-focusing and far-field mode compression at high powers. Asymmetric gain from tailored current profiles generate unconventional, null-less modes and lead to distributed gain- and loss-filtering mechanisms for increased beam quality output. A 5.2-7.7 W of filament-free power enables high-efficiency (70%) coupling into SMF-28, resulting in 3.1-5.5 W of fiber-coupled power for erbium-doped fiber amplifiers pumping with 0.72-W/A slope efficiency. The concept is shown to be robust against the shape of the profiles, inhomogeneities in both injection current and refractive index, and thermal lensing with proper submount design.