InGaN-based high-speed mini laser diode surpasses PAM-4 visible light links by over 30 Gbps

The advancement of next-generation wireless communication technologies demands ultra-high-speed visible light communication (VLC) systems to support applications ranging from underwater optical links to terrestrial high-capacity networks. Indium gallium nitride (InGaN)-based blue laser diodes (LDs) have emerged as pivotal components for high-speed VLC due to their superior modulation bandwidth. However, achieving data rates beyond 30 Gbps under simple modulation schemes remains challenging, as the bandwidth is limited by carrier transport effects, low differential gain in multiple quantum wells (MQWs) induced by carrier accumulation, and significant damping effects. In this work, we present an InGaN-based blue mini-LD architecture featuring triple $\mathrm{In_{0.18}Ga_{0.82}N/In_{0.05}Ga_{0.95}N}$ QWs, 50 nm waveguide layer, and a 300 $\upmu$m short cavity, designed to address these bottlenecks. Experimental characterization demonstrates a record-breaking $-$3 dB bandwidth of 8.4 GHz with a low damping factor of 0.211 ns for InGaN blue LD, surpassing prior state-of-the-art designs. Using this device, a VLC system that employs standard on-off keying (OOK) and four-level pulse amplitude modulation (PAM4) achieves unprecedented data rates of 20 and 33 Gbps, respectively. Under the Shannon limit, the data rate can exceed 37 Gbps. Our work resolves critical limitations in large-bandwidth InGaN LD development, providing a scalable pathway to meet the increasing demands of high-speed VLC networks, underwater communications, optical interconnects, and other bandwidth-intensive optical wireless applications.