Md. J. Miah, A. Boni, S. Arslan, D. Martin, P. Della Casa, and P. Crump

Published in:

IEEE Photonics J., vol. 14, no. 3, art. 1525505, doi:10.1109/JPHOT.2022.3165399 (2022).

Abstract:

GaAs-based, highly-efficient, kW-class, 1-cm laser bars with high peak power P_opt and improved beam quality in quasi-continuous-wave mode are presented. The use of an extreme-triple-asymmetric (ETAS) epitaxial layer structure diminishes power saturation of high-power bars at high driving current. The resulting ETAS bars with 4 mm cavity produce a record 1.9 kW peak power, limited by available current supply, with a maximum power conversion efficiency η_E = 67% at T_HS = 25 °C heat-sink temperature. Both P_opt and η_E have been increased further by operating the bars at T_HS = -70 °C. Sub-zero operation raises the P_opt to 2.3 kW and the maximum η_E to 74%. A second configuration of ETAS bars with optimized lateral layout is further realized to obtain narrow lateral beam divergence Θ up to 2 kA driving current, without sacrificing P_opt and η_E. A 2-3° lower Θ (95% power level) is observed over a wide operating range at room temperature. A high degree of polarization is also maintained across the whole operating range.

Index Terms:

Beam quality, beam parameter product, diode lasers, high efficiency, high-power lasers, laser bars, near field, far field, semiconductor lasers.

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