Low power submillimeter-wave mixing and responsivity properties of YBa2Cu3O7 hot-electron bolometers

Low power characteristics of superconducting hot-electron bolometric mixers using YBa2Cu3O7 are reported. Near 77 K, these mixers have a responsivity of 780 V/W using 8 nW of local oscillator (LO) power at 585 GHz. The responsivity can be shown to be truly bolometric. Heterodyne mixing at 87 GHz shows an overall conversion gain of −47 dB at 1.8 GHz intermediate frequency, using 3.3 mW of incident LO power. The intrinsic conversion gain is estimated to be −16 dB with 1 μW of LO power, close to the calculated optimal values.