High-power operation and lateral divergence angle reduction of broad-area laser diodes at 976 nm

• Published in: Optics and laser technology Vol. 141; p. 107145
• Main Authors: Liu, Yuxian, Yang, Guowen, Wang, Zhenfu, Li, Te, Tang, Song, Zhao, Yuliang, Lan, Yu, Demir, Abdullah
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Ltd 01.09.2021; Elsevier BV
• Subjects: 976 nm; Continuous radiation; Design modifications; Design optimization; Diode laser; Energy conversion efficiency; Epitaxy; High brightness; High efficiency; High power; Industrial applications; Low divergence angle; Semiconductor laser; Semiconductor lasers; Wave power; Waveguides; High power; 976 nm; Diode laser; High efficiency; High brightness; Low divergence angle; Semiconductor laser
• ISSN: 0030-3992; 1879-2545
• DOI: 10.1016/j.optlastec.2021.107145

•A flared waveguide is proposed to control the lateral divergence of diode lasers.•An epitaxial structure was presented with low loss and high power.•We showed an efficient reduction of the lateral divergence angle at high power.•We demonstrated 34.5 W output and reliable operation employing these designs. Broad-area diode lasers with high output power and low lateral divergence angle are highly desired for extensive scientific and industrial applications. Here, we report on the epitaxial design for higher output power and a flared waveguide design for reduced divergence, which leads to high power operation with a low lateral divergence angle. A vertically asymmetric epitaxial structure was employed and optimized for low internal optical loss and high efficiency to realize high output power operation. Using a flared waveguide design, the lateral divergence angle was efficiently reduced by decreasing the number of high-order lateral optical modes significantly. The flared waveguide design introduces a smooth modification of the ridge width along the cavity without deteriorating laser performance. Based on the optimized epitaxial and waveguide design, we scaled the waveguide width to realize high continuous-wave power of 34.5 W at 25 °C. A low lateral divergence angle of 8° and high power conversion efficiency of 60% were achieved at the operating power level of 25 W. The life test data (30 A at 45 °C for 39 units, 0 failures in 1000 h) demonstrated reliable operation illustrating the efficient design for reduced lateral divergence angle and high operating power.