Optically triggered switching of optically thick YBCO films

Thin films of high-T/sub c/ superconducting material were used to construct two different types of opening switches: the photoresistive switch and the inductively coupled switch. The former show two distinct switching components in 8000-AA films consisting of a slow bolometric response and a faster nonbolometric response. The fast nonbolometric component had risetimes of approximately 4 ns and falltimes of approximately 6 ns. The slower component was identified to be thermal in origin and was in good agreement with the one-dimensional heat flow model used to simulate the thermal photoresponse. The inductively coupled switch is a contactless switch where the superconducting film screens the flux coupling between two coils of a transformer. The optically induced switching was achieved with risetimes of approximately 50 ns. with a multiturn output coil. Short (150-ps) laser pulses containing energies of up to 3 mJ are used in both cases to perform the switching.<>