Extended Data Fig. 2: Schematic illustration of the mid-infrared pyrometric technique.
From: Electroluminescence and energy transfer mediated by hyperbolic polaritons

The technique uses optical chopping to detect the spectrally integrated signal (PMIR, integrated over the full spectral range of the detector) of an hBN-encapsulated graphene device (left, TR2 device with L × W = 35 × 35 μm2) due to the radiative emission of the SiO2 backgate. The setup was utilized to perform the pyrometric characterization of Fig. 3.