Optical characterization of a superconducting hotspot air-bridge bolometer

A superconducting bolometer with an on-chip lithographic terahertz antenna has been characterized in passive and active mode. Direct detection measurements made with 300K/77K blackbody sources yeld an optical efficiency of 10%. Time response of the bolometer has been obtained at 2.5 and 4.4 THz by illuminating the detector with quantum cascade lasers (QCL) showing a time constant of 1.2 μs. Here we report on the fabrication and the optical characterization of an antenna-coupled hot-spot microbolometer operating in vacuum at liquid helium temperature.