Plasmonically enhanced mid-IR light source based on tunable spectrally and directionally selective thermal emission from nanopatterned graphene*

We present a proof of concept for a spectrally selective thermal mid-IR source based on nanopatterned graphene (NPG). We solve the electrostatic problem of a conducting hyperboloid with an elliptical wormhole in presence of an in-plane electric field. The localized surface plasmons on the NPG sheet allow for the control and tuning of the thermal emission spectrum in the wavelength regime from 3µm to 12μm by adjusting the radius and period of holes in a hexagonal lattice structure. Our COMSOL calculations show an emission power of 11000 W/m² at 2000K for a bias voltage of 23V by controlling the temperature of the hot electrons through the Joule heating. By generalizing Planck’s theory to grey body and deriving the nonlocal fluctuation-dissipation theorem with nonlocal response of surface plasmons, we show that the coherence length of the graphene plasmons and the thermally emitted photons can be as large as 13µm and 150µm, respectively, providing the opportunity to create a phased arrays of nanoantennas represented by the holes in NPG. Using FDTD calculations, CMT, and RPA, we develop the model of a mid-IR light source, which will pave the way to graphene-based optical mid-IR communication, mid-IR color displays, and mid-IR spectroscopy.