Superconducting NbN Hot Electron Bolometer Mixer at Terahertz

摘要

Superconducting niobium nitride (NbN) hot electron bolometer (HEB) mixers at terahertz ( THz) 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 high-resistivity Si substrates. Double sideband (DSB) receiver noise temperatures of 698K at 0.65THz, 904K at 1.6THz, 1026K at 2.5THz and 1386K at 3.1THz have been obtained at 4.2K without corrections and using changeable input local oscillation (LO) power to eliminate the affects of direct detection and instability of the LO power. The excess quantum noise factor β of about 4 has been estimated using a quantum noise model.