A 25-micrometer Single-Photon-Sensitive Kinetic Inductance Detector

• Published in: Physical review. X Vol. 14; no. 4; p. 041005
• Main Authors: Day, Peter K., Cothard, Nicholas F., Albert, Christopher, Foote, Logan, Kane, Elijah, Eom, Byeong H., Basu Thakur, Ritoban, Janssen, Reinier M. J., Beyer, Andrew, Echternach, Pierre M., van Berkel, Sven, Hailey-Dunsheath, Steven, Stevenson, Thomas R., Dabironezare, Shahab, Baselmans, Jochem J. A., Glenn, Jason, Bradford, C. Matt, Leduc, Henry G.
• Format: Journal Article
• Language: English
• Published: American Physical Society 01.10.2024
• ISSN: 2160-3308; 2160-3308
• DOI: 10.1103/PhysRevX.14.041005

We report measurements characterizing the performance of a kinetic inductance detector array designed for a wavelength of 25 microns and very low optical background level suitable for applications such as a far-infrared instrument on a cryogenically cooled space telescope. In a pulse-counting mode of operation at low optical flux, the detectors can resolve individual 25-micron photons. In an integrating mode, the detectors remain photon noise limited over more than 6 orders of magnitude in absorbed power from 70 zW to 200 fW, with a limiting noise equivalent power of 4.6 × 10 − 20 W Hz − 1 at 1 Hz. In addition, the detectors are highly stable with flat power spectra under optical load down to 1 mHz. Operational parameters of the detector are determined including the efficiency of conversion of the incident optical power into quasiparticles in the aluminum absorbing element and the quasiparticle self-recombination constant. Published by the American Physical Society 2024