Cooperative emission in polymer thin films

We present a novel electro-optic Q-switching technique that is controlled by an ultrafast optoelectronic feedback loop. This loop can realize not only positive feedback to build a Q-switched pulse, but also negative feedback to stabilize amplitude of the Q-switched pulse. The key element of this feedback loop is a GaAs photoconductive switch that has picosecond response time' and lo9 R dark resistance. A specially designed GaAs photoconductive switch can stand a few kilovolts. Using this 1