Photonic crystal enhanced narrow-band infrared emitters

TLDR

The study aims to develop tunable, high‑power narrow‑band infrared emitters for sensing, spectroscopy, and thermophotovoltaic applications. The emitters use a metal‑coated silicon–air photonic crystal whose periodic hole lattice couples light into discrete surface plasmon modes, setting the emission wavelengths. Experimentally, the device emits mid‑IR radiation with a bandwidth ≤0.2 % and shows >90 % reflection except a narrow band with 90 % absorption, matching transfer‑matrix predictions.

Abstract

We have experimentally and theoretically developed a unique thermally stimulated midinfrared source that emits radiation within a narrow range of wavelengths (δλ/λ⩽0.2). The emission wavelengths are defined by the periodicity of a metal coated silicon–air photonic crystal etched into the emitter surface. The lattice of the holes in the metal mediate the coupling of light into discrete surface plasmon states. This yields surfaces with spectrally nonuniform infrared reflection properties where over much of the IR 90+% of photons are reflected yet, in a narrow spectral region, 90% absorption is observed. Transfer matrix calculations simulate well the position and strength of the absorption features. This technology will afford tunable infrared emitters with high power in a narrow spectral band that are critical for sensing, spectroscopy, and thermophotovoltaic applications.