Oral Presentation
Development of a Cryogenic Laboratory for SIS Mixer Characterization at NARIT
Presenter: Hannarong Janthaloet (National Astronomical Research Institute of Thailand (NARIT) & Chiang Mai University (CMU))
Superconductor-Insulator-Superconductor (SIS) mixers provide state-of-the-art sensitivity for millimeter- and submillimeter-wave heterodyne astronomy, achieving noise performance close to the quantum noise limit through photon-assisted quasiparticle tunneling. The development and validation of these receivers require dedicated cryogenic test facilities capable of evaluating device performance under realistic operating conditions. To support this effort, the National Astronomical Research Institute of Thailand (NARIT) has established a millimeter-wave cryogenic laboratory for SIS mixer testing and characterization.
Using this setup, a 230 GHz finline SIS mixer was characterized, beginning with DC measurements to confirm device operation. The direct observation of quantum tunneling current from the Josephson junction represents the first experimental measurement of this type conducted in Thailand. Receiver performance was evaluated using the Y-factor technique with ambient and liquid-nitrogen loads over an RF frequency range of 180-240 GHz and an IF bandwidth of 0.5-12 GHz. The measured double-sideband (DSB) noise temperature achieved a best value of approximately 157 K, demostrating stable operation, wide bandwidth, and high sensitivity. The establishment of this laboratory provides NARIT with the capability to assemble, test, and validate SIS receivers locally prior installation at a telescope. This capability is essential for future receiver development and supports planned SIS receiver upgrades for the Jame Clerk Maxwell Telescope (JCMT). The system has recently been extended to enable testing of SIS receivers at frequencies up to 500 GHz.
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