Open AccessNumerical design of three-dimensional gradient refractive index structures for beam shaping
Author(s) -
W. Minster Kunkel,
James R. Leger
Publication year - 2020
Publication title -
optics express
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.394
H-Index - 271
ISSN - 1094-4087
DOI - 10.1364/oe.405642
Subject(s) - optics , refractive index , paraxial approximation , refractive index profile , beam (structure) , diffraction , beam propagation method , m squared , materials science , diffraction efficiency , laser beam quality , physics , laser beams , laser
A numerical design method is demonstrated for gradient refractive index (GRIN) beam shapers embedded in a medium. The three-dimensional refractive index profile Δn(x, y, z) gradually changes the spatial characteristics of a beam during propagation. Diffraction effects such as beam expansion are controlled and compensated by the refractive index profile, resulting in efficient field transformations with no coherent artifacts. The solution is found using phase retrieval and a paraxial scalar wave beam propagation model. An example design is shown in which small changes in refractive index (Δn < 10 -3 ) are used to transform a beam over a device length of 10 mm.