Observation of supercurrent distribution in YBCO thin film devices by photoexcited THz radiation

A new method of imaging supercurrent distribution in high-T/sub c/ superconducting film devices using the photoexcited THz radiation is proposed and demonstrated. The images are obtained by scanning focused femtosecond Laser pulses on superconducting film devices with detecting the THz radiation. The characteristic distribution of the transport and persisting currents is obtained and interpreted in terms of the Bean critical state model.