Nonbolometric Infrared Detection in La2-xSrxCuO4 and YBa2Cu3Oy Epitaxial Thin Films

Abstract
The electrical responses to infrared radiation of La2-x Sr x CuO4(100) and YBa2Cu3O y (110) epitaxial thin films with relatively low T c values and J c values of 104–105 A/cm2 are studied using modulated laser light. These films show apparent nonbolometric responses at temperatures below the transition regions which are strongly dependent on the bias current. The difference in the observed responsivity between these high-T c materials and BaPb1-x Bi x O3 can be explained on the basis of nonequilibrium superconductivity.