J. R. G. Silva; B. Mirzaei; W. Laauwen; N. More; A. Young; C. Kulesa; C. Walker; A. Khalatpour; Q. Hu; C. Groppi; J. R. Gao
https://www.spiedigitallibrary.org/conference-proceedings-of-spie/10708/107080Z/42-HEB-receiver-at-47-THz-for-GUSTO/10.1117/12.2313410.short
GUSTO will be a NASA balloon borne terahertz observatory to
be launched from Antarctica in late 2021 for a
flight duration of 100-170 days. It aims at reviewing the life cycle of
interstellar medium of our galaxy by simultaneously mapping the three brightest
interstellar cooling lines: [OI] at 4.7 THz, [CII] at 1.9 THz, and [NII] at 1.4
THz; along the 124 degrees of the galactic plane and through a part of the
Large Magellanic Cloud. It will use three arrays of 4x2 mixers based on NbN hot
electron bolometers (HEBs), which are currently the most sensitive mixers for
high resolution spectroscopic astronomy at these frequencies.
Here we report on the design of a novel 4.7 THz receiver for
GUSTO. The receiver consists mainly of two subsystems: a 4×2 HEB quasi-optical
mixer array and a 4.7 THz multi-beam LO. We describe the mixer array, which is
designed as a compact monolithic unit. We show, for example, 10 potential HEB
detectors with the state of the art sensitivity of 720 K measured at 2.5 THz.
They have a small variation in sensitivity, being less than 3%, while also meet
the LO uniformity requirements. For the multi-beam LO we demonstrate the
combination of a phase grating and a single QCL at 4.7 THz, which generates 8
sub-LO beams, where the phase grating shows an efficiency of 75%. A preliminary
concept for the integrated LO unit, including QCL, phase grating and beam
matching optics is presented.
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