High Absorption per Unit Mass Subwavelength Structure as Uncooled Infrared Detector

A subwavelength perforated structure designed for a maximum absorption-to-mass ratio has been utilized to construct an uncooled infrared $(\lambda \sim 8-12\ \mu \mathrm{m})$ thermal detector operating in air with a noise equivalent temperature difference (NETD) of $23 \text{mK}$ and detectivity of $1.1\times 10^{9}\text{cm}\sqrt{\mathrm{H}\mathrm{z}}/\mathrm{W}$ while time constant is 1.5 ms. With a fill factor of $\sim 27\%$, the detector shows an average absorption per unit mass of $\sim 6.8\times 10^{12}\text{kg}^{-1}$ over the long-wave infrared regime. Mach-Zehnder interferometry has been used for optical readout of the detector.