High-Speed Visible Light Communication Based on a III-Nitride Series-Biased Micro-LED Array

Abstract

Visible light communication (VLC) using III-nitride light-emitting diodes (LEDs) offers many advantages such as license-free operation, high spatial diversity and innate security. In particular, micro-LEDs ( $\mu$ LEDs) are strong candidates for VLC due to their high modulation bandwidths. However, the low optical power of a single $\mu$ LED is a key factor limiting VLC performance. In this paper, we report an optimized series-biased $\mu$ LED array to achieve higher optical power while retaining high modulation bandwidth for high-speed VLC. An example array consisting of 3 × 3 40 $\mu$ m-in-diameter $\mu$ LED elements is presented here. At a current density of 3200 A/cm $^2$ in direct-current operation, the optical power and small signal 6-dB electrical modulation bandwidth of a blue-emitting series-biased $\mu$ LED array are over 18.0 mW and 285 MHz, respectively. The data transmission capabilities of this $\mu$ LED array are demonstrated by using on – off keying, pulse-amplitude modulation, and orthogonal frequency division multiplexing modulation formats over free space with the error-free data transmission rates of 1.95, 2.37, and 4.81 Gb/s, respectively.