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Register a new userDemonstration of Thermal Images Captured by a Backside Illuminated Transition Edge Bolometer
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Added by
Mehdi Fardmanesh Prof.
Publication date
2021
fields
Physics
and research's language is
English
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A high temperature superconducting detector was fabricated to capture the thermal images in room temperature background. The detector was made of YBa2Cu3O7-{delta} (YBCO) superconducting thin film deposited on an Yttria Stabilized Zirconia (YSZ) substrate, structurally modified for high responsivity performance. A very thin absorber layer was implemented on the backside of the detector to increase the absorption of the device at infrared (IR) range of frequencies. To capture thermal images, a movable off-axis parabolic mirror on XY plane was used for focusing the incoming IR radiation including the thermal signal of the objects onto the device surface. The captured thermal images belong to the objects within the temperature range between 300K and 400K, which correspond to our imaging optics.
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We show the proof-of-principle detection of light at 1550 nm coupled evanescently from a titanium in-diffused lithium niobate waveguide to a superconducting transition edge sensor. The coupling efficiency strongly depends on the polarization, the overlap between the evanescent field, and the detector structure. We experimentally demonstrate polarization sensitivity of this coupling as well as photon-number resolution of the integrated detector. The combination of transition edge sensors and lithium niobate waveguides can open the field for a variety of new quantum optics experiments.
We describe a superconducting transition edge sensor based on a nanoscale niobium detector element. This device is predicted to be capable of energy-resolved near-IR single-photon detection with a GHz count rate. The increased speed and sensitivity of this device compared to traditional transition edge sensors result from the very small electronic heat capacity of the nanoscale detector element. In the present work, we calculate the predicted thermal response time and energy resolution. We also discuss approaches for achieving efficient optical coupling to the sub-wavelength detector element using a resonant near-IR antenna.
At Argonne National Laboratory, we are developing hard X-ray (2 to 20 keV) Transition Edge Sensor (TES) arrays for beamline science. The significantly improved energy resolution provided by superconducting detectors compared to semiconductor-based energy-dispersive detectors, but with better collection efficiency than wavelength-dispersive instruments, will enable greatly improved X-ray emission and absorption spectroscopic measurements. A prototype instrument with 24 microwave-frequency multiplexed pixels is now in testing at the Advanced Photon Source (APS) 1-BM beamline. Initial measurements show an energy resolution ten times better (150 eV compared to < 15 eV) than the silicon-drift detectors currently available to APS beamline users, and in particular demonstrate the ability to resolve closely-spaced emission lines in samples containing multiple transition metal elements, such as integrated circuits. Comparing fluorescence spectra of integrated circuits measured with our TESs at the beamline to those measured with silicon detectors, we find emission lines and elements largely hidden (e.g. Hf alongside Cu) from a semiconductor-based detector but well resolved by a TES. This directly shows the strengths of TES-based instruments in fluorescence mapping.
Far-infrared Transition Edge Sensors (TESs) are being developed for the SAFARI grating spectrometer on the cooled-aperture space telescope SPICA. In support of this work, we have devised a cryogenic (90 mK) test facility for carrying out precision optical measurements on ultra-low-noise TESs. Although our facility is suitable for the whole of the SAFARI wavelength range, 34-230 $mu$m, we focus on a representative set of measurements at 60-110 $mu$m using a device having a Noise Equivalent Power (NEP) of 0.32 $mathrm{aW/sqrt{Hz}}$. The system is able to perform a range of measurements: (i) Dark electrical characterisation. (ii) Optical efficiency with respect to a partially coherent beam having a modal composition identical to that of an ideal imaging telescope. (iii) Optical saturation and dynamic range. (iv) Fast optical transient response to a modulated thermal source. (v) Optical transient response in the presence of high-level background loading. We describe dark measurements to determine the operating characteristics of a TES, and then compare predicted optical behaviour with measured optical behaviour. By comparing electrical and optical transient response, we were able to observe thermalisation in the device. We comment on the challenge of eliminating stray light.
Complex cryogenics is still a strong limitation to the spread of quantum voltage standards and cryogen-free operation is then particularly interesting for Josephson standards. The main difficulties in He-free refrigeration are related to chip thermalization. We tested different solutions and interface materials between the chip and the cooling surface, to improve thermal conduction. Some junctions were chosen as elements to dissipate electrical power, while some others were operated as on-chip temperature sensors. Indium foil between chip and Cu support was demonstrated to provide a good thermal interface suitable for programmable voltage standard operation. However, thermal conduction can be further increased by thermal contacting the chip at the top. Finally, general physical constraints in vacuum thermal contacts are analyzed in terms of known properties of thermal interfaces at cryogenics temperatures.
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