10 Mbps in-plane green light communication system made by InGaN/GaN MQWs device

Abstract

In this work, we demonstrate a green light in-plane communication system at 557 nm through a monolithic integration of two same structure MQWs devices-LED and PD, and waveguides on a GaN-on-Si wafer with InGaN/GaN superlattice layer. The MQW structures are responsible for the emission in the LED and photodetection in the PD. In addition, the device have the ability of luminescing and detecting simultaneously in quantum wells. The front side of device is completed by using e-beam evaporation, photolithography, etching. Since Si substrate is unfavorable for optical transmission due to strong visible light absorption. One last step is stripping of the Si substrate to increase the signal intensity received at the receiving side. As on-chip free-space transmission is hard to achieve due to the omnidirectional emission of LED, the installation of waveguides between LED and PD is beneficial for efficient transmission of optical signals. The optical and electrical properties of this communication system are characterized through series of measurement. To practically cognize the ability of transmission of the communication system, we use the system achieveing an in-panle transmission of PRBS signals modulated by non-return-to-zero on-off-keying (NRZ-OOK) at the speed of 10 Mbps, then analyze the result and the influence of other system factors such as resistive-capacitive (RC) time constant and junction capacitance of the receiver. According to the analysis of results, the system is able to transmitted and received PRBS signals at a rate of 10 Mbps.