A fully lithographed voltage-biased superconducting spiderweb bolometer

We describe the fabrication and characterization of superconducting transit ion-edge bolometers for astrophysical applications at far-infrared and mm w avelengths. The sensor is voltage biased and the current is measured with a superconducting quantum interference ammeter. Strong negative electrotherm al feedback keeps the sensor temperature nearly constant, reduces the respo nse time significantly, and improves linearity. It also makes the responsiv ity relatively insensitive to changes in optical background loading and ref rigerator temperature. The bolometers are made using standard microlithogra phic techniques suitable for fabrication of large scale arrays. Detailed me asurements of optical response are presented for a range of bias conditions and are compared with theory. Measured noise spectra are shown and a model for the noise is presented. (C) 1999 American Institute of Physics. [S0003 -6951(99)04206-0].