We report on a novel fluid actuation mechanism capable of achieving ultrafast actuation in micro and nanofluidic environment by utilizing laser pulse induced cavitation bubbles. A highly focused laser beam can initiate a vapor bubble with a rapidly expansion speed at more than 100 m/sec in few nanoseconds and an internal pressure of tens of MPa. Such a fast response and large force induced laser triggered cavitation bubble could strongly perturb the fluid flow near the focal point and the neighboring channel structures. We have demonstrated several novel applications based on this mechanism, including a high speed microfluid membrane switch with a cycle lifetime less than 6 μsec, and a high speed droplet device capable of generating highly uniform droplet at a speed of 10,000 droplets per second on demand.© (2010) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.