Detection and storage of femtosecond laser pulse signals by optical magnetic-flux-generation in a YBCO thin film loop

We studied the optical creation and modulation of magnetic flux quanta in a YBa/sub 2/Cu/sub 3/O/sub 7-/spl delta// thin film loop by observing terahertz emission excited with femtosecond laser pulses. The magnetic flux is created and modulated in the loops with a polarity controlled by means of optical supercurrent modulation. The results suggest a possible application of the superconductive loop as an optical flux-trap memory for the detection and storage of the femtosecond optical signals. The mechanism for the creation of the magnetic flux is discussed in relation to the current distribution in the loop.