Abstract

High-power GaAs-based diode lasers are critical components for material processing applications, and have high potential for use in additive manufacturing systems (AM) [1]. High power continuous-wave (CW) diode lasers with operating wavelength λ ~ 780 nm can enable higher build rates for AM of Ni-, Fe-, and especially Al-alloys due to the higher absorption compared to conventional λ = 1070 nm [2]. High output power P_out per device and high conversion efficiency η_E are required for reduced costs for industry in €/W however increasing P_out and ηE is challenging for 780 nm due to the available semiconductor materials. We select here TM-polarized lasers with a single GaAs_yP_1-yquantum well embedded in Al_xGa_1-xAs waveguide and cladding layers, as these are known to present higher P_out and ηE than lasers with InGaAsP or InAlGaAs quantum wells [3]. In our previous studies of 780 nm devices (pulsed pumps for Thulium-doped amplifiers) [4], an efficiency-optimized vertical structure was developed with increased vertical asymmetry, for reduced loss and vertical leakage. Peak efficiency was η_E = 57% (10 ms pulse 10 Hz repetition, heatsink temperature T_HS = 25°C) and peak P_out = 213 W (0.5 ms 10 Hz T_HS = 15°C) from single emitter with stripe width W = 1200 µm and resonator length of L = 6 mm.

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