Printed Metamaterial Based Uncooled Multi-Spectra Mid-IR Imaging For Deep Space Exploration
Mid-infrared (mid-IR) (3-16 μm) detection and imaging is increasingly becoming important for space explorations, spectroscopy, meteorology, chemical/biological identification, short range communication, flame detection, radiation thermometer, target tracking, night vision, remote sensing etc. However, to detect low energy mid-IR photons cryogenically cooled, expensive molecular beam epitaxy (MBE) grown ternary semiconductors like mercury-cadmium-telluride (HgCdTe) are needed. To avoid growth and cooling issues, the key challenge is to develop a detection technique which doesn’t depend on semiconductor bandgap effect. Various kinds of microbolometers primarily based on vanadium oxide (VOx) filled the gap and offer uncooled detection of IR radiations. However, microbolometers suffer from complex multi-step lithography, relatively low sensitivity, low responsivity slow response and lack of multi-spectral imaging/detection abilities. All of these make mid-IR detection/imaging an expensive and complicated process. Hence, there is a need for development of low cost, high sensitive, uncooled mid-IR detection techniques. The present proposal proposes to develop thin-film printed metamaterial based mid-IR frequency selective narrow as well as broad band absorbers which in conjunction with high sensitive, low noise “Nano-Wheatstone Bridge” based electronic detection circuit forms a large area printed detector/focal plane array. The key attributes of this metamaterial based detector is that it doesn’t need active cooling and the response can be tuned over any spectral range for multi-spectral detection/imaging. Based on the above benchmark technology, the following interrelated and advanced devices will be designed and fabricated: (a) a new frequency selective metamaterial absorber specially designed for electrical detection which is further tunable over mid-IR band using a specially designed IR liquid crystal; (b) a novel broadband 3D metamaterial absorber for high signal-to-noise ratio broadband IR detection/imaging; (c) “Nano-Wheatstone Bridge” based high sensitive, low noise electronic detection circuit to convert IR absorption to electrical signal; (d) multi-spectral imaging for “color” IR image formation; (e) The key objective will be to achieve a frequency selective sensitivity (D*) of ≥109 and response time (τ) of <= msec at ambient temperature in order to detect IR radiation < 10 pW (pico watt) over 1 Hz noise equivalent bandwidth.