Modal description of paraxial structured light propagation: tutorial

Here we outline a description of paraxial light propagation from a modal perspective. By decomposing the initial transverse field into a spatial basis whose elements have known and analytical propagation characteristics, we are able to analytically propagate any desired field, making the calculation fast and easy. By selecting a basis other than that of planes waves, we overcome the problem of numerical artifacts in the angular spectrum approach and at the same time are able to offer an intuitive understanding for why certain classes of fields propagate as they do. We outline the concept theoretically, compare it to the numerical angular spectrum approach, and confirm its veracity experimentally using a range of instructive examples. We believe that this modal approach to propagating light will be a useful addition to the toolbox for propagating optical fields. (c) 2021 Optical Society of America

Automated summary

This approach analytically propagates light waves by decomposing the initial field into a spatial basis with known propagation characteristics, overcoming numerical artifacts and offering intuitive understanding of certain types of field propagation. The theoretical concept is compared to numerical methods and experimentally verified, showing potential as a useful tool for propagating optical fields.