Submillimeter Detector Arrays
Arrays of Superconducting Direct Detectors for Supersensitive Imaging Radiometers of 1.0 – 0.2 mm Waveband Region
Tech Area / Field
- INF-ELE/Microelectronics and Optoelectronics/Information and Communications
- PHY-SSP/Solid State Physics/Physics
- INS-DET/Detection Devices/Instrumentation
- SAT-AST/Astronomy/Space, Aircraft and Surface Transportation
8 Project completed
Senior Project Manager
Tyurin I A
Russian Academy of Sciences / Institute of Radioengineering and Electronics, Russia, Moscow
- Institute of Microelectronics Technology and High Purity Materials, Russia, Moscow reg., Chernogolovka
- National Astronomical Observatory of Japan, Japan, Tokyo\nForschungszentrum Jülich GmbH / Institut fur Microstructure Research, Germany, Jülich\nCalifornia Institute of Technology / Jet Propulsion Laboratory, USA, CA, Pasadena\nState University of New York at Stony Brook / Department of Physics and Astronomy, USA, NY, Stony Brook\nEuropean Space Agency, The Netherlands, Noordwijk\nCardiff University, UK, Cardiff\nTohoku University / Graduate School of Science, Japan, Sendai\nPhysikalisch-Technische Bundesanstalt / Braunschweig Branch, Germany, Braunschweig
Project summaryInvestigation and development of superconducting direct detector arrays for radiometers on ground based astronomical telescopes of the 1.25 – 0.8 mm wavelength range (first stage) and for the 1.0 – 0.2 mm wavelength range radiometers for application in future space missions (second stage).
The proposed direct detector arrays are based on the superconducting transition edge sensors (TES). The superconducting transition takes place in single-layer superconducting thin-film structures or in bi-layer “superconductor-normal metal” thin film structures. The thin-film structures are fabricated with the minimal possible dimensions down to ~ 1 µm x 0.1 µm or less and with accuracy down to 0.01 µm to achieve the high sensitivity with a minimal possible absorber volume. The fabrication of such structures demands sophisticated microelectronics fabrication techniques based on electron beam lithography. The detector structures will operate at temperatures of about 0.3 Kelvin and lower. For optimal matching with the telescope optics the TES direct detectors will be coupled to an array of planar single- or double-polarized antennas through microstripe transformers without intermediate absorbers. Sensitivity of TES direct detectors estimated from their electrical characteristics measurements, is
10-19-10-20 W/Hz1/2 what is required for submillimeter astronomy. For fast imaging of distributed astronomical sources the direct detector arrays must have dimensions up to
Basic advantages of TES direct detector arrays:
Besides well known advantages of TES direct detector arrays additional advantages of proposed design of TES direct detectors arrats are the following:
- extremely small dimensions of direct detector absorbers providing by the electron beam lithography technology allow for the very high sensitivity;
- the using of microstrip antennas allows for good optical coupling of the detectors with the telescope beam;
- application of efficient multiplexing circuit for the biasing and the signals read-out using a new proposed projection method being analogous to computer tomography method using in the medicine and the combining of this method with the frequency domain biasing method proposed by Berkeley group. This is providing the strong reducing of the thermal load to the refrigerator owing to the significant reducing of amount of wires leading in the bias to detectors and leading received signals out of them as well as the significant improvement of the signal-to-noise ratio of the receiving system owing to parallel connection of detectors at low frequency read-out circuit;
- application of simple and efficient and rather precise in the same time method of operative measurement (calibration) of spectral characteristics and noise equivalent power of direct detector array using the radiation source based on the black body with variable temperature.
The work plan:
- Investigation of temperature dependences of resistance and IV-curves of microbrdges fabricated on the basis of single superconductive thin film structures as well as of bi-layer thin film “normal metal-superconductor” structures with the purpose of their parameters optimization when using as direct detector absorbers.
- Investigation and development of the fabrication process and modification of the existing technological line based on the electron beam lithography for fabrication of antenna arrays with TES direct detectors. Single thin titanium film structures as well as bi-layer thin film “molybdenum-palladium” structures will be used as the materials for direct detector absorbers; the niobium will be used as material for electrodes and niobium with gold (or other normal metals) coating will be used for matching antennas.
- Fabrication and investigation of 3 x 3 and 8 x 8 (x 2 for two polarizations) arrays of antennas with TES direct detectors.
- Investigation, development and fabrication of a submillimeter radiation source based on the black body with variable temperature mounted into the refrigerator for calibration of direct detector arrays.
- Development, fabrication and investigation of the detector readout multiplexer utilizing a combination of the projection and the frequency domain biasing methods.
- Development and fabrication of the optical camera comprising matching lenses and infrared radiation filters. Development and assembling of an integrated test bed on the basis of the 0.3 K refrigerator, optical camera, multiplexer and blackbody radiation measuring device.
- Tests and measurements of the characteristics of direct detector arrays in the 1.25 – 0.2 mm wavelength range.
- Installation of the 1.25 – 0.8 mm wavelength range test bed operating as radiometer prototype on the 6 m optical telescope and demonstration of its operation.