Dynamic response-based LEDs health and temperature monitoring

This paper presents a number of novel methods to measure the junction temperature and to estimate the health of gallium nitride light-emitting diodes (LEDs). The methods are based on measurements of the dynamic impedance and optical output. Our experimental analysis reveals temperature sensitive parameters of the electrical and optical responses. Moreover, a correlation between the non-radiative current characterizing the active region defects and the small-signal impedance is shown. The demonstrated methods can be applied to enhance existing temperature-monitoring techniques. The derived dependencies also build a foundation for advanced in-field health monitoring of the LEDs using the infrastructure of visible light communication systems. Such methods and techniques are valuable for predictive maintenance of solid state lighting systems.