Abstract High-power ultrafast superconducting switch (SCS) was made of an optically thick YBa 2Cu 3O 7 superconducting film (zero resistance critical temperature T c∼90 K and the critical current density J c∼10 6 A/cm 2 at T=78 K). The switch was biased with a 70-ns-pulsed supercritical current I∼2 I c ( I c is the critical current of the superconductor), which created a flux-flow state in the film, and synchronously activated with a 14-ps-optical pulse, which transferred the switch into the normal (resistive) state. It was found that the risetime, falltime, and duration of optically induced voltage transients depended on the optical pulse energy, time of heat diffusion from an optical hot spot, and the bias current dissipation in the optically activated part of the superconductor. The transient risetime consisted of the fast (less than 0.1 ns) and slow (tens of ns) components with the amplitudes dependent on laser fluence. The YBa 2Cu 3O 7 SCS, biased with nanosecond-pulsed supercritical currents and triggered with picosecond-optical-pulses, can be used for excitation of pulsed-antennas which radiate high-power, ultra-wide-frequency-band, and jitter-free signals in gigahertz frequency range. Practical limits of high-power optically triggered YBa 2Cu 3O 7 superconducting switches are discussed.