GaN-based blue micro-laser diodes for visible light communication

Visible light communication (VLC) is attracting growing interest for energy-efficient, high-bandwidth links for next-generation data centers. GaN-based blue edge-emitting micro-laser diodes (micro-LDs) with cavity lengths down to 40 μm are demonstrated based on optical resonance between a cleaved facet and an etched facet with laterally deposited distributed Bragg reflector. The threshold current as low as 9.6 mA and slope efficiency of 0.32 W/A are achieved for an 80 μm-cavity-length device. The VLC characteristics of 140 μm micro-LD show a broader −3 dB modulation bandwidth of 429 MHz and a higher data rate of 5.3 Gbps, compared with those of standard 500 μm LD. These results demonstrate the potential application of GaN-based blue edge-emitting micro-LDs as a compact and low-power laser platform for augmented/virtual reality displays and short-distance optical communication for inter-chip optical interconnections.