Characteristics of superconducting flux flow transistors under irradiation of femtosecond laser pulses

We have fabricated superconducting flux flow transistors with YBCO thin films and investigated the vortex flow characteristics under the irradiation of femtosecond laser pulses. The vortex flow velocity was calculated by the magnetic field dependence of the flow voltage. The obtained velocity without laser irradiation is 0.08-1.37 x 10(4) m/s for the bias current I-B = 0.4-0.8 mA. The flow voltage increased gradually when the irradiated laser power was up to 10 mW, however, it increased drastically when the laser power was more than 10 mW. The maximum velocity of 6.3 x 10(4) m/s was obtained at the laser power of 15 mW. The result indicates that the laser pulses excite the vortices and accelerate the vortex velocity. (C) 2003 Elsevier B.V. All rights reserved.