Response analysis and modeling of high temperature superconductor edge transition bolometers

One of the promising devices made of high temperature superconducting (HTSC) materials are edge transition bolometers. Since the discovery of high-temperature superconductors, many works have been focused on the application of these materials in different types of bolometers for the near to far infrared wavelength regime [l]-[9]. They can be used to detect electromagnetic radiation over the whole spectrum from x-ray to the far-infrared [1], [9]-[13]. The superconductor bolometers typically consist of patterned thin or thick superconducting films deposited on crystalline substrates such as MgO, SrTiO3, and LaA103. Their operation is based upon their steep drop in the resistance, R, at their transition temperature, Tc. The detector is typically held at a temperature close to the middle of the superconducting transition, where the dR/dT is maximum. When the detector is illuminated its temperature rises by an amount proportional to the input radiation power resulting in a ΔR. The response obtained by the above mechanism is the so called the bolometric, or equilibrium response, as opposed to typically faster non-bolometric or intrinsic response caused by other mechanisms such as direct depairing. A typical response of an YBCO sample versus temperature at low frequencies is shown in Figure 1.1.