High-speed modulation of GaN-based light emitting diode with embedded photonic crystals

Using GaN-based light-emitting diodes (LEDs) as a radio source for visible light communication (VLC) is one of alternative choice in a high-speed data system. However, the spontaneous radiative recombination lifetime in the multiple quantum wells (MQWs) usually restrict the modulation bandwidth of LEDs. For LEDs accompanied photonic crystal (PhC) structure, the guided photonic modes can be extracted with a shorter radiative recombination lifetime; therefore, improve the performance of the devices for VLC. In this paper, we compare various PhC structures with corresponding dynamic behaviors in both small- and large-signal modulation. Faster transient responses and higher efficiency of the out-coupled modes were obtained in the room-temperature time-resolved photoluminescence (TRPL) and Raman scattering measurement. Here, sub-GHz modulation of GaN-based PhCLED is demonstrated, and the PhCLED exhibits a higher bandwidth than the conventional LED structure. Our study also indicates that we can not just keep scaling down the masa size of LEDs to increase the operation frequency owing to the light output power may become dull and reduce the performance of VLC system