Radiative Cooling By Light Down Conversion Of Ingan Light Emitting Diode Bonded To A Si Wafer

Using the recently proposed process of radiative cooling by light down conversion, we demonstrate cooling of about 5K for InGaN light emitting diode (39 mg thermal load) that is self-heated up to 450K and bonded to a cooler, a 15 x 15 x 4 mm(3) Si wafer pumped with an above bandgap excitation from a 1.09-mu m diode laser. Cooling occurs due to the enhancement of thermal emission in an initially transparent Si wafer when the overall energy of multiple (about 20) below bandgap photons escaping the wafer exceeds the energy of the single pumped photon. The cooling efficiency amounts to 93%. (C) 2013 AIP Publishing LLC.