Volyanyuk S. New class of apodizing diaphragms on basis of the dye doped photopolymers

The formation of a prescribed spatial profile of laser radiation is required for many problems of nonlinear optics, holography, laser location, and technology. One of the methods of correction for the spatial distribution of laser radiation consists in inserting in the beam the elements whose optical characteristics depend on the radius. Soft or apodizing diaphragms belong to such elements. A new class of apodizing diaphragms (ADs), obtained by gradient photobleaching of initially uniform dyed polyurethaneacrylate films by adapted penumbra technique, is proposed. Two types of intracavity soft apertures are proposed: apodizing selectors that should be used with a separate Q switch and selectors combined with an optical switch (a single element contains a passive Q switch and an apodizing selector of transverse modes of the cavity). Soft apertures of the first type, produced on the basis of polyurethaneacrylate doped with the dithiobenzyl nickel complex, were used for transverse-mode selection in a Nd3+:YAG laser. Authors of this work study the dyes diffusion in the polyurethaneacrylate films in connection with the elaboration on mentioned basis the lasers cavity gradient elements - the soft amplitude diaphragms for selection and formation of the spatial profile of transversal cavity modes. In this paper, we solve several interrelated problems: we develop the technology of fabrication of Ads on the basis of dyed polyurethaneacrylate, study spatial profiles of ADs manufactured by this technique, and study specific features of selection of transverse modes by soft apertures in comparison with mode selection provided by hard metal diaphragms.