Characterization of a Far-Infrared Kinetic Inductance Detector Prototype for PRIMA

TL;DR

This paper presents the design and characterization of a prototype far-infrared kinetic inductance detector (KID) optimized for 210 microns, demonstrating low noise and high dynamic range suitable for space-based astrophysics observations.

Contribution

The study introduces a novel KID prototype optimized for 210 microns, with detailed fabrication and performance analysis showing promising NEP and dynamic range for space missions.

Findings

Achieved NEP of 9×10⁻²⁰ W/Hz^{1/2} at low optical loading.

Detector remains photon noise limited up to 20 fW of loading.

Demonstrated high dynamic range suitable for bright source observations.

Abstract

The PRobe far-Infrared Mission for Astrophysics (PRIMA) is under study as a potential far-IR space mission, featuring actively cooled optics, and both imaging and spectroscopic instrumentation. To fully take advantage of the low background afforded by a cold telescope, spectroscopy with PRIMA requires detectors with a noise equivalent power (NEP) better than $1 \times 10^{-19}$ W Hz$^{-1/2}$. To meet this goal we are developing large format arrays of kinetic inductance detectors (KIDs) to work across the $25-250$ micron range. Here we present the design and characterization of a single pixel prototype detector optimized for $210$ micron. The KID consists of a lens-coupled aluminum inductor-absorber connected to a niobium interdigitated capacitor to form a 2 GHz resonator. We have fabricated a small array with 28 KIDs, and we measure the performance of one of these detectors with an optical loading in the $0.01 - 300$ aW range. At low loading the detector achieves an NEP of $9\times10^{-20}$ W Hz$^{-1/2}$ at a 10 Hz readout frequency. An extrapolation of these measurements suggests this detector may remain photon noise limited at up to 20 fW of loading, offering a high dynamic range for PRIMA observations of bright astronomical sources.