Low Noise Terahertz Receivers Based on Superconducting NbN Hot Electron Bolometers

Jianhui Chen, Min Liang, Lin Kang +7 more

Low noise receivers based on superconducting niobium nitride (NbN) hot electron bolometer (HEB) mixers have been designed, fabricated and measured in the terahertz (THz) frequency range for applications in astronomy and cosmology. The NbN HEB mixer consists of a planar antenna and an NbN bridge connecting across the antenna's inner terminals on high-resistivity Si substrates. Double sideband (DSB) receiver noise temperatures of 920 K at 1.6 THz and 1630 K at 2.5 THz have been obtained at 4.2 K without corrections. Effects of Parylene C AR coating on the lens have been studied; with such a coating a lowest DSB receiver noise temperature of 1135 K at 2.5 THz has been obtained at 4.2 K.

Yi Jiang, Biaobing Jin, Weiwei Xu +3 more

J. Chen, Min Liang, Lin Kang +5 more

Low noise receivers using quasi-optical superconducting niobium nitride (NbN) hot electron bolometer (HEB) mixers have been designed, fabricated and measured in the terahertz (THz) frequency range for THz applications in astronomy and cosmology. The NbN HEB mixers consist of a planar complementary antenna and several nanometer (nm) thick NbN bridge connecting across the antenna's inner terminals on high-resistivity Si substrates. A double sideband (DSB) receiver noise temperature of 664 K at 0.76 THz, 920 K at 1.6 THz, 1630 K at 2.5 THz and 1710 K at 3.1 THz has been obtained without corrections and no anti-reflection (AR) coating on the surface of the lens.

Matvey I. Finkel, S. N. Maslennikov, Gregory N Gol'tsman

Min Liang, Jian Chen, Lin Kang +3 more

Low noise terahertz (THz) receivers based on superconducting niobium nitride (NbN) hot electron bolometer (HEB) mixers have been designed, fabricated and measured for applications in astronomy and cosmology. The NbN HEB mixer consists of a planar antenna and an NbN bridge connecting across the antenna's inner terminals on a high-resistivity Si substrate. To eliminate the influence of direct detection and instability of the local oscillation (LO) power, a wire grid has been used to change the input LO power for compensating the shift of bias current during Y-factor measurement. The double sideband (DSB) receiver noise temperatures at 4.2K without corrections have been measured from 0.65 to 3.1THz. The excess quantum noise factor β of about 4 has been obtained, which agrees well with the calculated value. Allan variance of the HEB has been characterized, and Allan time TA longer than 0.4s is obtained. We also estimated the temperature resolution of the HEB from the Allan variance and obtained the minimum temperature resolution of 1.1K using a Gunn oscillator with its multipliers at 0.65THz as an LO source.

Alexei D. Semenov, Heinz‐Wilhelm Hübers, Heiko Richter +4 more