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Improving the mode selection of bi-prism-like reflectors with intracavity amplitude masks

In a recent work it was demonstrated that efficient laser mode selection can be accomplished by replacing one of the laser mirrors by a bi-prism-like (flat-roof) reflector. In that work the objective was to generate a pure "dark beam" (a laser beam with a dark central region) for high resolution metrological applications. With the same objective in mind, in this work we present a new approach that leads to significant improvement of laser performance. This approach is based on an earlier work where a narrow amplitude mask over the middle of a conventional laser mirror was used to suppress the zero-order mode to facilitate oscillation of the first-order mode possessing the required characteristics. Starting from a similar configuration, in the present work we show that the performance can be optimized by combining a partially transmitting amplitude mask with a bi-prism-like reflector. Numerical simulations predict mode selectivity enhancement of at least a factor of 3 as compared to laser resonators with bi-prism-like reflectors alone.