Implementation of Micro-LED for High-Speed Optical Communication

Abstract

The exponential growth of AI and cloud computing is driving a massive data surge, exposing a fundamental data movement bottleneck. As traditional links encounter power and bandwidth limitations, Micro-LED technology emerges as a pivotal solution. This thesis explores its potential as an efficient electrical-to-optical converter through two paradigms: a “See-and-Talk” concept for optical wireless communication and a “Wide-and-Slow” architecture for fiber-optic communication, addressing critical implementation challenges across device, circuit and system levels.

Firstly, a GaN-based Micro-LED array was demonstrated for underwater wireless optical communication. By utilizing optical power aggregation, the system achieved 165 Mbps over 37.7 m and extended the transmission distance to 73.5 m at 90 Mbps. These results validate the Micro-LED array’s potential for high-attenuation environments.

Secondly, a full-color RGB Micro-LED pixel was presented with a compact equivalent circuit model. System-level simulations based on this model demonstrated a PAM-4 data rate of 1.1 Gbps. This work establishes a viable pathway for integrated multi-color devices that can simultaneously support display and communication.

Thirdly, a high-resolution active-matrix Micro-LED driver was developed to overcome the instability of conventional 2T1C circuits by adopting a capacitor-less SRAM-based 8T0C pixel architecture. The system was prototyped using a driver SoC fabricated in 180 nm BCD process integrated with full HD GaN Micro-LED array. It achieved 8-bit grayscale display and 3.2 Mbps PAM-4 communication, validating the feasibility of the 8T0C architecture for single-chip dual-function solutions.

Finally, a high-speed 28 nm CMOS PAM-4 optical transmitter with an integrated thermal loop was designed to mitigate emitter thermal instability. The loop suppressed current variation from 6.42% to 0.73% over 25∘C to 125∘C. Anticipating future device maturity, the transmitter’s capability was verified using a high-bandwidth VCSEL model. Simulations demonstrated 64 Gbps PAM-4 transmission with an open eye at 125∘C. This provides a robust transmitter design for future high-bandwidth Micro-LEDs.

Date of Award	2026
Original language	English
Awarding Institution	The Hong Kong University of Science and Technology
Supervisor	Chik Patrick YUE (Supervisor) & Zhaojun LIU (Supervisor)