A new type of rf source, LASERTRON, is studied for a future high-energy electron-positron linear collider. In LASERTRON, a pulsed electron beam is extracted from a photocathode irradiated by a pulsed laser beam. The electron beam is then accelerated into a cavity from which rf power is extracted. Three prototypes of LASERTRON are fabricated and their fundamental characteristics are studied. The maximum rf power of 1.6 kW is extracted successfully at a rf frequency of 2884 MHz.