Jenna L. Kloosterman, Darren J. Hayton, Yuan Ren, Tsung-Yu Kao, Neils Hovenier, Jian-Rong Gao, Teun M. Klapwijk, Qing Hu, Christopher K. Walker, John L. Reno
We report on a heterodyne receiver designed to observe the astrophysically important neutral atomic oxygen [OI] line at 4.7448 THz. The local oscillator is a third-order distributed feedback Quantum Cascade Laser operating in continuous wave mode at 4.756 THz. A quasi-optical, superconducting NbN hot electron bolometer is used as the mixer. We recorded a double sideband receiver noise temperature (T^DSB_rec) of 815 +/- 12 K, which is ~7 times the quantum noise limit (hf/2kB) and an Allan variance time of 15 s at an effective noise fluctuation bandwidth of 18 MHz. Heterodyne performance was confirmed by measuring a methanol line spectrum.
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http://arxiv.org/abs/1208.5776
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