Beam shaping in laser resonators and coherent laser arrays: An overview and current state of the art

Coherent beam shaping can be performed inside laser resonators by filtering the amplitude or the phase of the circulating wave. Along with providing a designer-shaped output, these methods can improve laser performance by suppressing higher-order modes and extracting maximum gain. Under certain conditions, phase filtering is shown to improve modal discrimination by separating modes into bound (low-loss) modes and unbound (high-loss) modes. Mode shapes in resonator arrays are shown to depend on the architecture of the array. In some cases, these architectures can be designed to improve modal discrimination or increase the tolerance to resonator path-length errors.