Photoinduced superconducting nanowires in Gd-Ba-Cu-O films
  We report the fabrication of high Tc superconducting wires by photodoping a GdBa2Cu3O{6.5} thin film. An optical near-field probe was used to locally excite carriers in the system at room temperature. Trapping of the photogenerated electrons define a confining potential for the conducting holes in the CuO planes. Spatially resolved reflectance measurements show the photogenerated nanowires to be ~ 250 nm wide. Electron diffusion, before electron capture, is believed to be responsible for the observed width of the wires. 
R. S. Decca, H. D. Drew, B. Maiorov, J. Guimpel, and E. Osquiguil