MECSEL with dynamic transverse mode control

Abstract

The phenomenon of Laue diffraction is known in crystallography. Conceptually, its optics resemble coherent forward scattering by a periodic refractive index structure. It has been shown that compact and efficient spatial filters within short solid-state laser cavities can be made utilizing the Laue diffraction approach. While manufacturing spatial filters based on Laue diffraction proves to be comparatively simpler than those relying on Bragg diffraction, challenges persist due to the typically three-dimensional nature of these structures. To simplify the implementation of such spatial filters, we present a new approach. We propose a new type of spatial filter based on the complex refractive index, namely an amplification grating built into a relatively short surface-emitting laser cavity with a semiconductor membrane externalcavity surface-emitting laser. This represents a very special case where we achieve this goal by self-imaging inside the resonator, creating a virtual photonic crystal spatial filter that increases the brightness of the output laser beam. The simplicity and effectiveness of this approach are thoroughly validated in our paper.