Lithographically patterned superconductor bolometer detectors for visible and near-infrared radiation incorporating wavelength selective light absorbing elements

Composite dye/superconductor sensors which can discriminate different wavelengths of light in the visible and near-infrared regions have been fabricated. By lithographically patterning 1500 angstrom thick films of the superconductor YBa2Cu3O7_-δ on MgO substrates, arrays of microbridges have been created. A layer of dye dispersed in a polymeric matrix is deposited on top of each bridge to create the wavelength selective light absorbing element. Each meandering path bridge is approx. 20μm wide and approx. 10 mm long. The device functions in a different manner to traditional semiconductor-based light sensing technologies in which a dye structure serves the role of a filtering agent. Here, the response of the hybrid dye/superconductor element is amplified at wavelengths strongly absorbed by the dye layer. Such devices represent the initial steps towards a larger structure capable of simultaneously sensing wavelength bands from the visible through to the infrared. In addition to dye sensitization method, another approach to adding wavelength selectivity to detectors is described here in which interference effects in micromachined microbolometers are exploited.