Dynamic laser control using feedback from a gain grating

We demonstrate that self-induced gain gratings can provide nonlinear optical feedback that results in single frequency selection and passive self Q-switching of a conventional linear laser cavity. An experimental Nd:YAG laser system is described that yields a temporally-smooth 20 ns pulse at 1.064 /spl mu/m. In addition, we show that the feedback has phase-conjugate properties that permit "flower-like" mode formation even though the azimuthal symmetry of the cavity is broken.