Dai Yingqiu, Fu Ting, Chen Jingxuan, Tang Chenyan, Wang Xueyou, Wang Yufei, Zheng Wanhua
Opt Express. 2024 Sep 23;32(20):36010-36020. doi: 10.1364/OE.534568.
Broad-area lasers (BA) are practical for producing high output power. However, under a high current operation, high-order modes are easily excited, resulting in the broadened linewidth. Here, based on mode engineering of double-side transverse photonic crystals (TPCs) combined with a longitudinal high-order surface grating, a narrow-linewidth electrically-pumped broad-area laser with high power emission only using I-line lithography is demonstrated. By matching the high-order modes of the wide main waveguide with TPC bands, the effective volume of the high-order modes is expanded, while the fundamental mode remains unchanged. Then, single-lateral mode operation is achieved by selective pumping only for the main waveguide due to the significant distinction in modal gain between the fundamental mode and the high-order modes. In addition, a 27-order grating is constructed above the main waveguide to keep the laser operating in single-longitudinal mode. In the experiment, the device shows an output power of 115 mW, a lasing wavelength of 1552.94 nm with a side-mode suppression ratio (SMSR) of 59.26 dB, a narrow linewidth of 443 kHz, and a relative intensity noise (RIN) < -135 dB/Hz at 600 mA, thus has the potential to meet the needs in fields such as coherent optical communication and LiDAR.
大面积激光器（BA）对于产生高输出功率很实用。然而，在高电流运行下，高阶模式很容易被激发，导致线宽变宽。在此，基于双侧横向光子晶体（TPC）与纵向高阶表面光栅相结合的模式工程，展示了一种仅使用I线光刻技术的具有高功率发射的窄线宽电泵浦大面积激光器。通过将宽主波导的高阶模式与TPC能带相匹配，高阶模式的有效体积得以扩大，而基模保持不变。然后，由于基模和高阶模式在模态增益上存在显著差异，通过仅对主波导进行选择性泵浦实现了单侧模式运行。此外，在主波导上方构建了一个27阶光栅，以保持激光器在单纵模下运行。在实验中，该器件在600 mA时显示出115 mW的输出功率、1552.94 nm的激射波长、59.26 dB的边模抑制比（SMSR）、443 kHz的窄线宽以及< -135 dB/Hz的相对强度噪声（RIN），因此有潜力满足相干光通信和激光雷达等领域的需求。
