Simultaneous emission–detection operation of vertical-structure LED

Abstract

The overlap between the emission and detection spectra of the LED allows one single LED to exhibit both light emission and detection simultaneously, wherein the LED can function as a transmitter and a receiver at the same time for communication using light. Here, we report the simultaneous emission-detection operation of vertical-structure LED, which is implemented on an III-nitride-on-silicon platform. The III-nitride epitaxial films are thinned without etch hard mask to suppress optically-confined modes inside the LED. The simultaneous emission-detection operation occurs when the forward voltage of the LED is larger than the turn-on voltage Vth. The measured current is a sum of the driving current and the photocurrent generated by external light. By integrating a feedback circuit, the photocurrent is extracted from the superimposed current and consequently converted into a control signal to regulate the driving current, leading to automatically adjust light output of the LED.