NbN Vacuum Bridge Bolometer Arrays With Room Temperature Readout Approaching Photon Noise Limited THz Imaging Applications

We study the applicability of superconducting NbN vacuum bridge bolometer arrays with room temperature readout electronics to passive THz imaging applications. We show that sufficient bandwidth for video-rate mechanical scanning in terms of stability and noise can be reached by exploiting the divergences of the bolometer noise temperature and the differential impedance at the I-V curve minimum. Experimental electrical noise equivalent power is 9 fW/Hz^1/2 . This would correspond to ~10 times the photon noise in a bandwidth of 0.5 THz and is comparable to the expected clutter in passive THz images due to atmospheric fluctuations.