Method for cavity dumping a q-switched laser

Abstract

A method for cavity dumping a Q-switched laser having a gaseous gain medium to obtain submicrosecond output pulses, typically controllably variable between ten and three hundred nanoseconds at a high pulse repetition frequency typically up to at least twenty-five thousand pulses per second is disclosed. In a laser adapted for continuous wave operation, a combination of a retardation element and an electrooptic modulator provides a first polarization state to intracavity radiation incident onto an intracavity polarization coupler oriented to couple out of the cavity radiation having the first polarization state to provide a high loss condition to the cavity to maintain the laser below threshold. A voltage applied quickly to the modulator converts the first polarization state to a second polarization state to provide a low loss condition to the cavity to Q-switch the laser. Terminating the voltage near the maximum Q-switch buildup converts the polarization to the first polarization state which is cavity dumped by the polarization coupler to provide an output pulse. Controlling the fall time of the voltage termination controls the pulse width of the output pulse while controlling the duration of the voltage controls the energy of the output pulse.