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

A high-Tc superconducting bolometer has been constructed using a YBa2Cu3Ox thin-film meander line 20 μm wide and 76 000 μm 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), and the NEP is 5.7×10−8 W/(Hz)1/2 . 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.