Characterization of high-power white leds for VLC applications

Abstract

During the last years, visible light communications (VLC) have been proposed for providing connectivity while ensuring satisfactory illumination in both indoor environments and also specific outdoor scenarios without the need of deploying complex infrastructures for that purpose. Transmission for VLC is carried out through light-emitting diodes (LEDs), which correspond to semiconductors based on PN-junction materials with a direct gap. In this sense, the current flow plays a major role in the behavior and performance of these devices for VLC. Therefore, characterizing the electrical response of high-power white LED results mandatory for the successful implementation of VLC. At this point, it is worth noting that the electrical characterization is usually not available for high-power LEDs since, in fact, determining these characterization results challenging. In this sense, there exist some measurement instruments such as LCRs or impedance analyzers typically employed for characterizing materials and passive electrical components. However, these kinds of instruments are subject to a limited input impedance and a maximum value of forwarding current. In this work, the electrical characterization of the LED LXHL-BW02 of Luxeon is analyzed to show that typically commercial instrumentation for characterizing these devices is limited for high-power LEDs, which may provide polluted results when these limitations are not considered. After that, the characterization of the LXHL-BW02 based on a lock-in amplifier is proposed.

Keywords

• Visible light communications
• Light emitting diode
• Impedance analyzer
• Lock-in amplifier