ULTRAFAST OPTOELECTRONIC SWITCHES BASED ON HIGH-T-C SUPERCONDUCTORS

We present measurements of the ultrafast reflectivity change of YBa2Cu 3O7-delta thin films upon femtosecond laser excitation. The response i s attributed to the breaking of Cooper pairs and the subsequent recomb ination of quasiparticles. In a current-biased superconducting bridge, these transient processes lead to the generation of picosecond electr omagnetic pulses, which. can be directly detected by measuring tile em itted radiation from the bridge in a quasi-optical setup. We show that the emitted pulse can be calculated from the arl-optical measurements .