Controlled thermal emission of polarized infrared waves from arrayed plasmon nanocavities

We have demonstrated thermal emission of linearly polarized and narrow-band midinfrared waves from subwavelength gratings of narrow and deep rectangular cavities engraved on a Au surface. 100-nm-wide and 1000-nm-deep, high-aspect trenches were accurately manufactured by inversion from master molds. Organ pipe resonance of surface plasmons in the cavities exhibits a Lorentzian emission peak centered at 2.5–5.5μm. The maximum emittance reaches 0.90 and the peak width Δλ∕λ is as narrow as 0.13–0.23. This simple emitter is expected to play a key role in the infrared sensing technologies for analyzing our environment.