MOPAs use these devices in serial with an amplifier to measure their gain. The addition of an etalon with the appropriate finesse parameter to one of these devices can be used to convert multimodal output into unimodal output. The exciplex variant of this device operates by triggering the formation and subsequent separation of unstable noble gas-halide complexes. Resonance trapping can increase the upper level lifetime  in these devices by channeling the output from transitions to the ground state back into the device's medium. Pulsed output in these devices may be accomplished by Q-switching, in which the cavity is periodically obstructed to prevent resonance. These devices operate by pumping from a ground state to a metastable state, from
MOPAs use these devices in serial with an amplifier to measure their gain. The addition of an etalon with the appropriate finesse parameter to one of these devices can be used to convert multimodal output into unimodal output. The exciplex variant of this device operates by triggering the formation and subsequent separation of unstable noble gas-halide complexes. Resonance trapping can increase the upper level lifetime  in these devices by channeling the output from transitions to the ground state back into the device's medium. Pulsed output in these devices may be accomplished by Q-switching, in which the cavity is periodically obstructed to prevent resonance. These devices operate by pumping from a ground state to a metastable state, from which a cascade is induced, a technique known as population inversion. For 10 points, name these devices that emit coherent light by means of stimulated emission.
MOPAs use these devices in serial with an amplifier to measure their gain.
laser 