Construction and performance of a high-temperature-superconductor composite bolometer

A high-Tc superconducting bolometer has been constructed using a YBa2Cu3O(x) thin-film meander line 20 microns wide and 76,000 microns long, deposited on a SrTiO3 substrate. Radiation is absorbed by a thin film of Bi with well-characterized absorption properties deposited on a Si substrate in contact with the SrTiO3. At 1.8 Hz the measured bolometer response to a 500-K blackbody is 5.2 V/W (820 V/W extrapolated to dc). The impact of apparent nonohmic behavior at the transition is discussed, as are ways of reducing the observed 1/f noise. The response time is 32 s and is dominated by the heat capacity of the SrTiO3 substrate.