UC Santa Barbara

High contrast direct imaging is one of the most technologically challenging techniques used to search for exoplanets and circumstellar disks. Despite its difficulty, it is incredibly powerful since it enables further characterization of these companions. Ground-based high contrast observations require Adaptive Optics (AO) systems to correct wavefront aberrations caused by the atmosphere and starlight suppression techniques like coronagraphy to reject on-axis starlight. The last two decades have seen several extreme AO systems come online, such as SPHERE at ESO, GPI at VLT, SCExAO at Subaru, and MagAO-X at LCO. As these AO systems have matured they have significantly improved achievable contrast ratios, but they are still limited by diffracted and scattered light that causes an interference patterns called speckles in astronomical images. To search for fainter sources these systems will need to improve their ultimate contrast ratios via improved wavefront control and novel data processing techniques.

MKIDs are photon counting detectors capable of measuring a photon's arrival time with microsecond accuracy, its energy (or color), and the position it struck within an image. When used as astronomical cameras MKIDs can generate images with spectral information tens of thousands of times per second without readout noise associated with their conventional counterparts. This ability enables novel noise mitigation techniques and higher signal to noise ratios in astronomical images.

This thesis will present the design, development, and commissioning of XKID, an MKID-based instrument behind the Magellan Extreme Adaptive Optics (MagAO-X) system at the Las Campanas Observatory (LCO). It is a near-infrared integral field spectrograph (IFS) whose goal is to search for and characterize protoplanets and exoplanets and to eventually operate as a real-time Focal Plane Wavefront Sensor (FPWFS). The first-light commissioning run for XKID took place in March 2023 and is slated to return to LCO during future MagAO-X runs. It is the third MKID camera commissioned for high contrast imaging and the first to be used behind a visible-light AO system.

I will also discuss the discovery and characterization of a potentially substellar companion that was found using the MKID Exoplanet Camera (MEC) at the Subaru Observatory on Maunakea. The discovery was enabled as part of a targeted direct imaging search and was made in conjunction with 3 other instruments on the Subaru and Keck Telescopes: CHARIS, VAMPIRES, and NIRC2.

Next, I will introduce an algorithm that was developed for the identification and rejection of cosmic rays in MKID datasets that has since been successfully integrated into the MKID Data Reduction Pipeline.

Finally, I will report the results of an experiment measuring the dark count rates measured by large-format MKID arrays. This is an essential task for better understanding and characterizing the performance of MKIDs when they are unilluminated which will be integral as they push forward to more photon-starved regimes. This experiment also showed that the nominal performance of MKIDs in the dark is comparable to that of cutting-edge conventional detectors at their quietest.