48 W continuous-wave output power with high efficiency from a single emitter laser diode at 915 nm

Abstract

Improving the power and efficiency of 9xx-nm broad-area laser diodes reduces the cost of laser systems and expands applications. LDs with more than 25 W output power combined with power conversion efficiency (PCE) above 65% can provide a cost-effective high-power laser module. We report a high output power and high conversion efficiency laser diode operating at 915 nm by investigating the influence of the laser internal parameters on its output. The asymmetric epitaxial structure is optimized to achieve low optical loss while considering high internal efficiency, low series resistance, and modest optical confinement factor. Experimental results show an internal optical loss of 0.31 cm-1 and internal efficiency of 96%, in agreement with our simulation results. Laser diodes with 230 μm emitter width and 5 mm cavity length have T0 and T1 characteristic temperatures of 152 and 567 K, respectively. The maximum power conversion efficiency reaches 74.2% at 5 °C and 72.6% at 25 °C, and the maximum output power is 48.5 W at 48 A (at 30 ℃), the highest reported for a 9xx-nm single emitter laser diode. At 25 oC, a high PCE of 67.5% is achieved for the operating power of 30 W at 27.5 A, and the lateral far-field angle with 95% power content is around 8°. Life test results show no failure in 1200 hours for 55 laser diodes. In addition, 55.5 W output was achieved at 55 A from a laser diode with 400 μm emitter width and 5.5 mm cavity length. A high PCE of 64.3% is obtained at 50 W with 47 A. © 2023 SPIE.