PICOSECOND PHOTORESPONSE OF YBA2CU3O7-X THIN-FILMS

The photoresponse of current-biased YBa2Cu3O7-x (YBCO) microbridges, p atterned in 100-nm-thick, high-quality epitaxial films on LaAlO3, has been characterized by means of an electro-optic sampling technique. Th e photoresponse from 100-fs laser pulses (390-nm wavelength) was measu red to be in the form of Gaussian-shaped pulses with the width as shor t as 0.8 ps. The physical origin of the photoresponse signal can be at tributed to a nonequilibrium electron heating mechanism. The measured signal represents, in our opinion, the intrinsic photoresponse of YBCO .