Proposal for superconducting photodiode

Abstract

We propose a concept of a superconducting (SC) photodiode-a device that transforms the energyand 'spin' of an external electromagnetic (EM) field into the rectified steady-state supercurrent anddevelop a microscopic theory describing its properties. For this, we consider a two-dimensionalthin film cooled down below the temperature of SC transition with the injected dc supercurrentand exposed to an external EM field with a frequency smaller than the SC gap. As a result, wepredict the emergence of a photoexcited quasiparticle current, and, as a consequence, oppositelyoriented stationary flow of Cooper pairs. The strength and direction of this photoinducedsupercurrent depend on (i) such material properties as the effective impurity scattering time andthe nonequilibrium quasiparticles' energy relaxation time and (ii) such EM field properties as itsfrequency and polarization.