Fig. 3: Nanocrystalline graphene-based emitter.

a Schematic of the hybrid device. Nanocrystalline graphene strip integrated atop cross-bar PhC cavity. b Three-dimensional finite difference time domain (3D FDTD) simulated spectrum (normalized) of light outcoupled from one of the ends of the cross-bar photonic crystal (PhC) cavity. The symmetric design of the PhC cavity leads to equal incandescent emission at both sides. The resonance modes are labeled in roman numbers (I–IX) in the plot. c Scanning electron microscope (SEM) image of the cavity region with NCG strip atop cavity. The waist of NCG strip is 250 nm in width, thickness – 5 nm. d Recorded spectra of enhanced thermal emission outcoupled from couplers A (green curve) and C (red curve) of an electrically-biased NCG strip using 120uA (source-drain voltage 35.5 V). The spectrum from the nanocrystalline graphene (NCG) strip (blue curve) was acquired with the polarizer parallel to TE mode of the waveguide. The enhancement factors and coupling efficiency of incandescent emission into the I, III, and V resonance modes are F_I = 5.3, F_III = 80.6 and F_V = 58.7, β_I = 84.1%, β_III = 98.7%, and β_V = 98.3%, respectively. e Measured spectra of the incandescent emission detected at coupler C, projected onto different polarization angles with a polarization filter. The dashed white line marks the polarization axis of the spectra acquired at couplers A and C. The measurements were performed at 77 K. The simulated and fabricated cross-bar PhC cavity contains N = 45 segments in each Bragg mirror with a lattice period of a = 458 nm.