Mixing experiments have been performed at frequencies from 4 to 20 GHz on Nb thin‐film superconducting hot‐electron bolometers varying in length from 0.08 to 3 μm. The intermediate frequency (IF) bandwidth is found to vary as L−2, with L the bridge length, for devices shorter than √12 Le−ph≊1 μm, with Le−ph the electron‐phonon length. The shortest device has an IF bandwidth greater than 6 GHz, the largest reported for a low‐Tc superconducting bolometric mixer. The conversion efficiencies range from −5 to −11 dB (single sideband, SSB). For short bridges, the mixer noise temperature is found to be as low as 100 K (double sideband, DSB), with little length dependence. The local oscillator power required is small, ≊10 nW. Such mixers are very promising for low‐noise THz heterodyne receivers.
Length scaling of bandwidth and noise in hot‐electron superconducting mixers
P. J. Burke, R. J. Schoelkopf, D. E. Prober, A. Skalare, W. R. McGrath, B. Bumble, H. G. LeDuc; Length scaling of bandwidth and noise in hot‐electron superconducting mixers. Appl. Phys. Lett. 3 June 1996; 68 (23): 3344–3346. https://doi.org/10.1063/1.116052
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