106 research outputs found
A Comparison of Fundamental Noise in Kinetic Inductance Detectors and Transition Edge Sensors for Millimeter-wave Applications
Kinetic inductance detectors (KIDs) show promise as a competitive technology
for astronomical observations over a wide range of wavelengths. We are
interested in comparing the fundamental limitations to the sensitivity of KIDs
with that of transition edge sensors (TESs) at millimeter wavelengths,
specifically over the wavelengths required for studies of the Cosmic Microwave
Background (CMB). We calculate the total fundamental noise arising from optical
and thermal excitations in TESs and KIDs for a variety of bath temperatures and
optical loading scenarios for applications at millimeter wavelengths. Special
consideration is given to the case of ground-based observations of 100 GHz
radiation with a 100 mK bath temperature, conditions consistent with the
planned second module of the QUBIC telescope, a CMB instrument. Under these
conditions, a titanium nitride KID with optimized critical temperature pays a
few percent noise penalty compared to a typical optimized TES.Comment: 6 pages, 2 figures, Proceedings of 15th International Workshop on Low
Temperature Detectors (LTD-15, Pasadena, California, June 2013), To be
published in the Journal of Low Temperature Physics (JLTP
Nanostructured Vanadium Oxide Uncooled Bolometers and Method of Fabrication
The present invention relates to uncooled microbolometers which can be integrated in future thermal instruments engaged in land imaging on future observatories. The present invention includes: (1) developing and characterizing a microstructured VOx thin film, and, (2) fabricating an uncooled microbolometer array over the 8-14 micron spectral band
Developing a Novel Platform for Characterizing Thermoelectric Materials for Uncooled Detectors for Land Imaging Applications
Thermal land imaging (imaging at ~8-14 micron optical wavelength) is an essential tool for understanding and managing terrestrial freshwater resources. Current thermal imaging instruments employ low temperature detectors, which require cryocoolers. Consequently, cost-saving reductions in size, weight, and power can be achieved by employing uncooled detectors. One uncooled detector concept, which NASA is pursuing, is a thermopile detector with sub-micron thick doped-Si thermoelectric materials. In order to characterize the thermoelectric properties of the doped silicon, we designed and optimized a novel apparatus. This simple apparatus measures the Seebeck coefficient with thermally isolated stages and LABVIEW automation. We optimized thermal stability using PID tuning and optimized the thermal contact between the thin film samples and stages using electrically conductive springs. Utilizing our apparatus, we measured the Seebeck coefficient of 0.45 micron thick phosphorus-doped single crystal Si samples bonded to alumina substrates. Using these Seebeck coefficient measurements and four-wire electrical resistivity measurements, we determined the relationship between the thermoelectric figure of merit and dopant concentration. These characterization results for doped-Si will guide our thermopile detector design to provide an optimal and competitive detector alternative for future thermal imaging instruments
Design and Performance of A High Resolution Micro-Spec: An Integrated Sub-Millimeter Spectrometer
Micro-Spec is a compact sub-millimeter (approximately 100 GHz--1:1 THz) spectrometer which uses low loss superconducting microstrip transmission lines and a single-crystal silicon dielectric to integrate all of the components of a diffraction grating spectrometer onto a single chip. We have already successfully evaluated the performance of a prototype Micro-Spec, with spectral resolving power, R=64. Here we present our progress towards developing a higher resolution Micro-Spec, which would enable the first science returns in a balloon flight version of this instrument. We describe modifications to the design in scaling from a R=64 to a R=256 instrument, as well as the ultimate performance limits and design concerns when scaling this instrument to higher resolutions
Overview of the Design, Fabrication and Performance Requirements of Micro-Spec, an Integrated Submillimeter Spectrometer
Micro-Spec is a compact submillimeter (350-700 GHz) spectrometer which uses low loss superconducting niobium microstrip transmission lines and a single-crystal silicon dielectric to integrate all of the components of a grating-analog spectrometer onto a single chip. Here we present details of the fabrication and design of a prototype Micro-Spec spectrometer with resolution, R64, where we use a high-yield single-flip wafer bonding process to realize instrument components on a 0.45 m single-crystal silicon dielectric. We discuss some of the electromagnetic design concerns (such as loss, stray-light, cross-talk, and fabrication tolerances) for each of the spectrometer components and their integration into the instrument as a whole. These components include a slot antenna with a silicon lens for optical coupling, a phase delay transmission line network, parallel plate waveguide interference region, and aluminum microstrip transmission line kinetic inductance detectors with extremely low cross-talk and immunity to stray light. We have demonstrated this prototype spectrometer with design resolution of R64. Given the optical performance of this prototype, we will also discuss the extension of this design to higher resolutions suitable for balloon-flight
Properties of Superconducting Mo, Mo2n and Trilayer Mo2n-Mo-Mo2n Thin Films
We present measurements of the properties of thin film superconducting Mo, Mo2N and Mo2N/Mo/Mo2N trilayers of interest for microwave kinetic inductance detector (MKID) applications. Using microwave resonator devices, we investigate the transition temperature, energy gaps, kinetic inductance, and internal quality factors of these materials. We present an Usadel-based interpretation of the trilayer transition temperature as a function of trilayer thicknesses, and a 2-gap interpretation to understand the change in kinetic inductance and internal resonance quality factor (Q) as a function of temperature
Optimization of an Optical Testbed for Characterization of EXCLAIM u-Spec Integrated Spectrometers
We describe a testbed to characterize the optical response of compact
superconducting on-chip spectrometers in development for the Experiment for
Cryogenic Large-Aperture Intensity Mapping (EXCLAIM) mission. EXCLAIM is a
balloonborne far-infrared experiment to probe the CO and CII emission lines in
galaxies from redshift 3.5 to the present. The spectrometer, called u-Spec,
comprises a diffraction grating on a silicon chip coupled to kinetic inductance
detectors (KIDs) read out via a single microwave feedline. We use a prototype
spectrometer for EXCLAIM to demonstrate our ability to characterize the
spectrometers spectral response using a photomixer source. We utilize an
on-chip reference detector to normalize relative to spectral structure from the
off-chip optics and a silicon etalon to calibrate the absolute frequency
Developing a New Generation of Integrated Micro-Spec Far Infrared Spectrometers for the EXperiment for Cryogenic Large-Aperture Intensity Mapping (EXCLAIM)
The current state of far-infrared astronomy drives the need to develop
compact, sensitive spectrometers for future space and ground-based instruments.
Here we present details of the -Spec spectrometers currently in
development for the far-infrared balloon mission EXCLAIM. The spectrometers are
designed to cover the m range with a resolution of $\rm R\
=\ \lambda / \Delta\lambda\ =\ 512\rm 638\ \mu\rm \mu\rm R = 64\ \muM{=}2{\sim}8\times10^{-19}\rm W/\sqrt{Hz}\rm \mu$-Spec
spectrometers for EXCLAIM.Comment: 9 pages, 5 figures, to appear in the Proceedings of the SPIE
Astronomical Telescopes + Instrumentation (2022
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