Accurate Measurement and Fast Prediction of Optothermal Properties of LED Arrays

In recent years, the utilization of light-emitting diode (LED) arrays in many applications has grown significantly. However, most of the conventional methods are only applicable to single-chip LED measurement. In multichip LED measurement, there is little consideration of the optothermal coupling among arrays under actual operating conditions, resulting in inaccurate measurement of optothermal parameters of LED arrays. In this work, we propose a method for accurate optothermal measurement based on phase-sensitive detection (PSD) to independently extract the emission spectrum of the LED under test (LUT) from the entire emission array by injecting different duty cycles of pulse current into the LUT. The temperature-sensitive parameter (TSP)-full-width at half-maximum (FWHM) of the LUT spectrum is utilized to determine the junction temperature. This method can accurately determine the optothermal distribution of LED arrays under actual operating conditions, regardless of chip size and packaging types. In addition, combining the lightweight Transformer network, the prediction of the optothermal distribution in LED arrays is significantly boosted within 20 s with the Pearson correlation coefficients of the results better than 0.96. The proposed method is experimentally validated by two LED arrays, including junction temperature, thermal coupling, and optothermal distribution among arrays.