High-speed GaN-based laser diode with modulation bandwidth exceeding 5 GHz for 20 Gbps visible light communication

• Junfei Wang, Junhui Hu, Chaowen Guan, Yuqi Hou, Zengyi Xu, Leihao Sun, Yue Wang, Yuning Zhou, Boon Ooi, Jianyang Shi, Ziwei Li, Junwen Zhang, Nan Chi, Shaohua Yu, and Chao Shen
• received 01/03/2024; accepted 03/18/2024; posted 03/19/2024; Doc. ID 516829
• Abstract: Visible light communication (VLC) based on laser diodes demonstrates great potential for high data rate maritime, terrestrial, and aerial wireless data links. Here, we design and fabricate high-speed blue laser diodes (LDs) grown on c-plane gallium nitride (GaN) substrate. This was achieved through active region design and miniaturization towards a narrow ridge waveguide, short cavity length, single longitudinal mode Fabry-Perot laser diode. The fabricated mini-LD has a low threshold current of 31 mA, and slope efficiency of 1.02 W/A. A record modulation bandwidth of 5.9 GHz (-3 dB) was measured from the mini-LD. Using the developed mini-LD as a transmitter, the VLC link exhibits a high data transmission rate of 20.06 Gbps adopting the bit and power loading discrete multitone (DMT) modulation technique. The corresponding bit error rate is 0.003, satisfying the forward error correction standard. The demonstrated GaN-based mini-LD has significantly enhanced data transmission rates, paving the path for energy-efficient VLC systems and integrated photonics in the visible regime.