A 25-micron single photon sensitive kinetic inductance detector

TL;DR

This paper presents a kinetic inductance detector array sensitive to 25-micron photons, capable of resolving single photons and operating near the photon noise limit over a wide power range, suitable for space telescope applications.

Contribution

The paper introduces a novel 25-micron kinetic inductance detector array with high sensitivity, stability, and photon counting capabilities for far-infrared space telescope use.

Findings

Photon resolution at 25 microns demonstrated.

Detector remains photon noise limited over six orders of magnitude in power.

High stability with flat power spectra down to 1 mHz.

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 six orders of magnitude in absorbed power from 70 zW to 200 fW, with a limiting NEP of 4.6 x 10^-20 W/rtHz 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.