Two components in femtosecond optical response of Y0.7Pr0.3Ba2Cu3O7-delta thin films in superconducting state

We studied the optical response of Y0.7Pr0.3Ba2Cu3O7-delta (YPBCO) thin fil ms by means of a femtosecond time-resolved pump-probe method, and found tha t its response quite differs significantly from that of YBa2Cu3O7-delta (YB CO) thin films. It is revealed that there are two components in the transie nt reflectivity change Delta R(t)/R of the YPBCO thin film in the supercond ucting state. The temperature dependence of Delta R(t)/R suggests that the one component originates from the photoexcitation of superconducting layers and the other originates from that of normal layers. The origin of these t wo components is discussed in relation to the electronic structure of YPBCO .