Enhanced narrowband mid-IR thermal radiation enabled by plasmonic stacked gratings

We demonstrate tailored thermal radiation in mid-infrared wavelength range with intriguing capabilities of high emissivity, narrowband spectra, and sharp angular response. The proposed thermal emitters consist of stacking a two-dimensional metallic grating on top of a one-dimensional dielectric Bragg grating (BG). It is interesting to find that the light interaction between the metallic grating and the BG gives rise to impendence matching at wavelengths located in the photonic bandgap of the BG, and allow enhanced polarization-dependent emissivity, selective resonance response, and high radiation directivity. We investigate the plasmonic resonance by exploring various properties and functions including tuning spectral selectivity and tailoring bandwidth at different light polarization and angle of incidence. The developed plasmonic stacked gratings could pave the way towards novel integrated infrared source platforms for various applications such as thermal analysis, imaging, security, biosensing, and medical diagnosis.