Here, we introduce the kinetic inductance current sensor (KICS), a novel readout technology based on the nonlinear current dependence of the kinetic inductance in a superconductor. The KICS takes the form of a superconducting resonator with small cross-section inductor, and current input from a TES or similar device causes shifts in the resonant frequency, enabling a sensitive measurement of the TES current. Additionally, the KICS makes use of a superconducting switch, which is used to trap a persistent current in the resonator, reducing noise and bias line pickup and enabling nearly arbitrary frequency tunability. We demonstrate the KICS through the readout of a TES optimized for 1550 nm photon detection, where we measure a resolving power, R, above 5, already matching the performance of a conventional SQUID readout of the same device.
While large arrays of microwave kinetic inductance detectors (MKIDs) have been demonstrated with photon noise limited performance, imperfect frequency placement due to fabrication non-uniformity has led to resonators that collide with their frequency neighbors. Though physically yielded, the excess cross talk means that they are unusable for science applications. This would lead to reduced performance when placed on telescopes such as the CCATs FYST. However, we can use the LED trimming method developed at NIST to identify the non-uniformities, the resonator location to frequency correspondence, and then re-etch the resonators to correct them to an optimal position. This process has been demonstrated on a CCAT 280 GHz MKID array. We will show the results of the trimming of 3456 resonators on the array, and how the yield would be improved while maintaining the optical performance of the pixels. This demonstrates a path towards ideal wafer-scale MKID arrays.
The development of direct absorbing kinetic inductance detectors (KIDs) for broadband far-infrared (FIR) observations designed to meet the needs of present and future telescopes is presented. This development was initiated to investigate the potential for upgrading the High-resolution Airborne Wideband Camera Plus (HAWC+) instrument on the Stratospheric Observatory for Infrared Astronomy (SOFIA) with KIDs; but also has applications generally for FIR detectors. These detectors consist of backside-illuminated KIDs on a silicon substrate where the hybrid TiN/Al inductor forms a resistive wire grid with broadband absorption. Detectors can be configured to absorb in either one or two polarizations with a pixel filling factor of around 80%. A novel two-layer meta material anti-reflection coating, and a sub-quarter-wavelength backshort allow for greater than 85% detection efficiency over the ultra-wide 1 to 6 THz bandwidth. These detectors require no focal plane focusing optics such as feedhorns or microlenses, do not require fragile membranes, and utilize proven and straightforward fabrication methods. The optical and microwave design of these detectors is presented. Additionally, the performance of test devices is quantified. This includes measurements of the AR coating effectiveness, detector noise equivalent powers, and detector internal quality factors under the relevant loading levels for the HAWC+ instrument. This information is used to assess the potential benefit of upgrading the HAWC+ instrument with these new detectors and to determine the applicability of this technology for other future FIR detectors.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.