Electrical tuning of emissivity and linewidth of thermal emission spectra

Here, we report on the postfabrication tuning of thermal emission spectra using photonic crystal resonators interacting with $n$-type quantum wells. Our method is based on the voltage control of intersubband absorption in the quantum wells, which allows the continuous tuning of both the thermal emission intensity and the linewidth. By adjusting an applied bias to match the intersubband absorption rate with the radiative rate of the resonator, we realize the maximization of the emissivity (0.7) of a narrowband thermal emission peak ($Q=157$). Even narrower thermal emission ($Q>200$) is also demonstrated with the same device by increasing the applied bias.