Optically triggered fast switching of high temperature superconductors is demonstrated by subjecting thin films of YBCO to 150 psec pulses from a Nd:YAG laser (&lgr;=1.06 &mgr;m). Films prepared by single target sputtering and by coevaporation are used to switch current densities of up to 105A/cm2in times as fast as 2 nsec. The magnitude of the response is indicative of a bolometric effect. The transient nature of the response can be explained by simple heating at temperatures above 20 K, whereas at lower temperatures there are signs of hot electron transport. Above 20 K optically thick films can be switched from the superconducting state to a voltage state in 2 nsec by biasing the film close to the critical current. In all cases, the return to the superconducting state takes place over tens of nsec, in agreement with thermal cooling by the substrate. Some design considerations for using a superconducting fast opening switch for pulsed power applications are discussed.