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
• Main Authors: Jianmei Shi, Chengao Yang, Yihang Chen, Tianfang Wang, Hongguang Yu, Juntian Cao, Zhengqi Geng, Zhiyuan Wang, Haoran Wen, Hao Tan, Yu Zhang, Dongwei Jiang, Donghai Wu, Yingqiang Xu, Haiqiao Ni, Zhichuan Niu
• Format: Article
• Language: English
• Published: Cambridge University Press 2024-01-01
• Subjects: antimonide semiconductor lasers; far-field; mode control
• Online Access: https://www.cambridge.org/core/product/identifier/S2095471924000239/type/journal_article
• ISSN: 2095-4719; 2052-3289

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.