A 25-micrometer Single-Photon-Sensitive Kinetic Inductance Detector
Peter K. Day, Nicholas F. Cothard, Christopher Albert, Logan Foote, Elijah Kane, Byeong Ho Eom, R. Basu Thakur, R. M. J. Janssen, Andrew D. Beyer, P. M. Echternach, Sven van Berkel, Steven Hailey-Dunsheath, Thomas R. Stevenson, Shahab O. Dabironezare, J. J. A. Baselmans, Jason Glenn, C. M. Bradford, H. G. LeDuc
Abstract
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 <a:math xmlns:a="http://www.w3.org/1998/Math/MathML" display="inline"> <a:mrow> <a:mn>4.6</a:mn> <a:mo>×</a:mo> <a:msup> <a:mn>10</a:mn> <a:mrow> <a:mo>−</a:mo> <a:mn>20</a:mn> </a:mrow> </a:msup> <a:mtext> </a:mtext> <a:mtext> </a:mtext> <a:mi mathvariant="normal">W</a:mi> <a:mtext> </a:mtext> <a:msup> <a:mi>Hz</a:mi> <a:mrow> <a:mo>−</a:mo> <a:mn>1</a:mn> </a:mrow> </a:msup> </a:mrow> </a:math> 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