|
By with MIAO Wei
Schematic picture of the measurement setup, where the 850 GHz LO source is phase locked to a microwave reference with a harmonic Schottky diode mixer.
Superconducting quasi-optical phonon-cooled NbN HEB receivers are currently the first choice for heterodyne spectroscopy at frequencies above 1.5 THz. For the development of high-sensitivity superconducting HEB receivers, it is crucial to have a good understanding of the input RF noise contribution because it indeed plays an important role in the entire receiver noise temperature. In terms of simulation results based on the hot spot model, it was found that the output noise of HEB mixers is nearly linearly decreased with the mixer’s bath temperature when the HEB mixer is operated at its optimum dc-bias regime under appropriate local-oscillator (LO) signal pumping and the effect of this decrease on the receiver output power can be well corrected. Thus researchers of Mm & Submm Lab. led by Prof. SHI Shengcai propose to use an intersecting lines technique to characterize the input RF noise temperature of a quasi-optical superconducting NbN HEB receiver. With this intersecting lines technique technique, the input RF noise temperature of a superconducting NbN HEB receiver has been well investigated at 850 GHz. The work by MIAO Wei, ZHANG W., ZHOU K.M., ZHANG K., DUAN W.Y., YAO Q.J., and SHI S.C. (corresponding author), accepted by IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY, has been published online (http://ieeexplore.ieee.org/Xplore/defdeny.jsp?url=http%3A%2F%2Fieeexplore.ieee.org%2Fstamp%2Fstamp.jsp%3Ftp%3D%26arnumber%3D6362177%26userType%3Dinst&denyReason=-134&arnumber=6362177&productsMatched=null&userType=inst) for more details. |
