Development of the 1.3-1.5 THz band superconducting HEB mixer receivers for ASTE 10 m telescope

T. Shiino, L. Jiang, R. Furuya, T. Yamaguchi, S. Shiba, T. Sakai, N. Sakai, Y. Watanabe, O. Ohguchi, H. Maezawa, T. Yamakura, Y. Irimajiri, S. Yamamoto

Research output: Contribution to conferencePaperpeer-review

Abstract

In the THz region, there exist many spectral lines of various fundamental atoms, ions and molecules, which give us novel information on chemical and physical state of interstellar clouds including star and planet forming regions. Although observations of these lines have successfully been started with Herschel HIFI, further observations with higher angular resolution from the ground based telescope are still important by utilizing some THz atmospheric windows. With this in mind, we have been developing superconducting HEB (Hot Electron Bolometer) mixers for the THz heterodyne sensing at The University of Tokyo. By use of these mixers, we are preparing a cartridge-type THz heterodyne receiver for the 0.8-0.9 THz and 1.3-1.5 THz bands. This receiver will be installed on ASTE 10 m telescope (Atacama Chili) for molecular line observations in the above regions. The receiver is the ALMA cartridge type with a single beam. It can observe dual bands (0.9 THz and 1.3-1.5 THz) simultaneously in the DSB mode by using the wire grid. We employ the in-house waveguide HEB mixers for the both bands. Although SIS mixers now show a better performance than HEB mixers at 0.9 THz, we use the HEB mixer to demonstrate observation capability of our HEB mixer. The LO signal is coupled with the RF signal by wire grids placed on the 4 K stage. As for the LO signal source, we use frequency-multiplier chains driven by the microwave synthesizer. We use NbTiN and NbN superconducting films fabricated on a quartz substrate for the HEB mixers. The NbN film formed directly on a quartz substrate does not show high Tc. Hence, we use the AlN buffer layer between the quartz substrate and the NbN film (Shiino et al. 2010). The thickness of superconducting microbridges is set to be 10.8 nm for NbTiN and 6 nm for NbN. The receiver performance has been measured in the test apparatus. The minimum receiver noise temperatures achieved so far are 450 K for the 0.8 THz NbTiN and NbN mixers, 1050 K for the 1.5 THz NbN mixers, and 570 K for the 1.5 THz NbTiN mixers. The noise performance of the 1.5 THz NbTiN mixer is excellent. The noise temperatures show significant dependence on microbridge size (0.5~3.0 μm width and 0.1~0.4 μm length). We will be able to achieve better noise performance by optimizing the microbridge dimensions carefully.

Original languageEnglish
Pages146
Number of pages1
Publication statusPublished - 2011
Event22nd International Symposium on Space Terahertz Technology 2011, ISSTT 2011 - Tucson, AZ, United States
Duration: 2011 Apr 252011 Apr 28

Conference

Conference22nd International Symposium on Space Terahertz Technology 2011, ISSTT 2011
CountryUnited States
CityTucson, AZ
Period11/4/2511/4/28

ASJC Scopus subject areas

  • Computer Networks and Communications
  • Space and Planetary Science
  • Electrical and Electronic Engineering
  • Atomic and Molecular Physics, and Optics
  • Radiation

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