High-Sensitivity Superconducting Detectors for Far-Infrared Space Astrophysics

The far-IR is a notoriously difficult portion of the electromagnetic spectrum to observe, but offers enormous discovery potential in astrophysics due to the orders-of-magnitude lower dust extinction compared to visible wavelengths. Astronomical background limited observations in the far-IR require a 4 K telescope in space with highly-sensitive detectors. These detectors must have a high multiplex factor and low hardware complexity to be deployed in sufficient numbers in space. Thus, large arrays of high-sensitivity far-IR detectors have been a long sought-after technology for astrophysicists. Superconducting detectors are the clear choice for far-IR measurements, because semiconducting detectors become band-gap limited – and therefore cannot achieve the required sensitivities – at these wavelengths. Furthermore, far-IR semiconducting detectors are not scalable to large enough arrays. Transition Edge Sensors (TESs) were a potential candidate because, in theory, they could achieve the required sensitivities. However, decades of research on high-sensitivity TESs have not yielded successful results, and TESs also require significant hardware complexity which is difficult to implement in space. Kinetic Inductance Detectors (KIDs) were invented to reduce this hardware complexity, as thousands of KIDs can be read out on a single line with standard commercially available RF electronics. KIDs have surpassed the sensitivity requirement for far-IR space spectroscopy. This thesis presents the culmination of high-sensitivity far-IR TES development at the Jet Propulsion Laboratory (JPL) and Caltech, followed by the initial development of high-sensitivity far-IR KIDs. These KIDs were able to surpass the sensitivity requirement for far-IR spectroscopy, and offer a definitive path forward for deployment in space. Following this achievement, the Probe Far-Infrared Mission for Astrophysics (PRIMA), a far-IR probe-class space telescope which will deploy these KIDs, was selected by NASA for a phase A study. This thesis describes the development of these KIDs, as well as future demonstrations that must be accomplished for successful deployment on PRIMA.