Precise mode control of mid-infrared high-power laser diodes using on-chip advanced sawtooth waveguide designs

• Published in: High power laser science and engineering Vol. 12
• Main Authors: Shi, Jianmei, Yang, Chengao, Chen, Yihang, Wang, Tianfang, Yu, Hongguang, Cao, Juntian, Geng, Zhengqi, Wang, Zhiyuan, Wen, Haoran, Tan, Hao, Zhang, Yu, Jiang, Dongwei, Wu, Donghai, Xu, Yingqiang, Ni, Haiqiao, Niu, Zhichuan
• Format: Journal Article
• Language: English
• Published: Cambridge, UK Cambridge University Press 01.01.2024
• Subjects: antimonide semiconductor lasers; Design; Diodes; Etching; Far fields; far-field; High power lasers; Infrared lasers; Lasers; Microstructure; mode control; Molecular beam epitaxy; Ratios; Room temperature; Semiconductor lasers; Simulation; Waveguides; far-field; mode control; antimonide semiconductor lasers
• ISSN: 2095-4719; 2052-3289
• DOI: 10.1017/hpl.2024.23

Power scaling in conventional broad-area (BA) lasers often leads to the operation of higher-order lateral modes, resulting in a multiple-lobe far-field profile with large divergence. Here, we report an advanced sawtooth waveguide (ASW) structure integrated onto a wide ridge waveguide. It strategically enhances the loss difference between higher-order modes and the fundamental mode, thereby facilitating high-power narrow-beam emission. Both optical simulations and experimental results illustrate the significant increase in additional scattering loss of the higher-order modes. The optimized ASW lasers achieve an impressive output power of 1.1 W at 4.6 A at room temperature, accompanied by a minimal full width at half maximum lateral divergence angle of 4.91°. Notably, the far-field divergence is reduced from 19.61° to 11.39° at the saturation current, showcasing a remarkable 42% improvement compared to conventional BA lasers. Moreover, the current dependence of divergence has been effectively improved by 38%, further confirming the consistent and effective lateral mode control capability offered by our design.