New Broadband Mid-Infrared Detector Design Achieves 50-90% Absorption Efficiency
Researchers have developed a backshort-free Lumped Element Kinetic Inductance Detector (LEKID) architecture using a Ti40V60 superconducting alloy that achieves 50–90% absorption efficiency across the 12.5–30 micrometer mid-infrared wavelength range. Unlike conventional LEKIDs, which rely on narrowband resonant quarter-wavelength cavities, this design suppresses reflection by impedance-matching the meander's sheet resistance to the silicon substrate and confines transmission via evanescent wave effects. The advance simplifies focal plane array fabrication and could benefit applications in astrophysics and time-resolved infrared spectroscopy, including at Free-Electron Laser facilities.
A team of researchers has presented a new absorber architecture for mid-to-far-infrared (MIR-FIR) detectors that eliminates the need for the backshort cavities traditionally used in Lumped Element Kinetic Inductance Detectors (LEKIDs). The design uses a dense metallic meander fabricated from a Ti40V60 superconducting alloy, illuminated through a silicon substrate. Broadband absorption is achieved through two simultaneous mechanisms: impedance matching between the meander's sheet resistance and the silicon substrate's wave impedance suppresses front-side reflection, while the sub-wavelength periodicity of the meander prevents transmission into free space through evanescent wave confinement. Together, these effects drive efficient Ohmic dissipation, yielding experimentally measured absorption efficiencies of 50–90% across the 12.5–30 micrometer range, as characterized using infrared radiation from the IR Free-Electron Laser at RRCAT, India. A test LEKID resonator was also fabricated and characterized to evaluate the Ti40V60 alloy's suitability as an active superconducting detector material. The cavity-free approach significantly reduces fabrication complexity for focal plane arrays and offers the broadband response needed for next-generation detectors in astrophysics and laboratory-based infrared spectroscopy.
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The work is a preprint and has not yet undergone peer review.
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- arXiv physicsCenter
High-Efficiency Broadband Mid-Infrared Absorption in Asymmetrically Matched Metallic Meanders: Development of Ti40V60 Alloy based LEKIDs for Mid-Far IR
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