Measurement of the penetration depth of superconducting thin films by optoelectronic sampling techniques

The magnetic penetration depth of YBa/sub 2/Cu/sub 3/O/sub 7-/spl delta// (YBCO) thin films has been determined as a function of temperature by using picosecond optoelectronic sampling techniques. Electrical pulses of 8 ps full width at half maximum were generated on photoconductive switches by a mode-locked Nd:YAG pumped dye laser and propagated on superconducting delay lines which were 250 mm in length. The measured behavior at low temperature (T