Motivation
Modeling electromagnetic propagation is often used in the PDRG to analyze the link between the transverse modes of a laser and the laser beam profile. As the modal field at the emission surface (the “near-field”) determines the beam field at a distance away (the “far-field”), electromagnetic propagation modeling can help us determine what modes are lasing (especially relevant when characterizing coherently coupled VCSEL arrays) and potentially inform the waveguide/laser design process (see “Direct Semiconductor Diode Laser Mode Engineering and Waveguide Design” in Resources).
The Methods
There are various computational methods of modeling the propagation of electromagnetic fields. Fourier optics methods are relatively simple and efficient. A few methods we commonly use include Fraunhofer propagation (for near-field to far-field propagation problems) and Fresnel Transfer Function propagation (for field propagation at closer distances), as described in “Computational Fourier Optics: A MATLAB Tutorial” (see in Resources).
Resources
- David Voelz’s “Computational Fourier Optics: A MATLAB Tutorial” is a good reference for modeling E&M propagation
- EMPropagation.jl: Julia package for electromagnetic propagation
- “Direct Semiconductor Diode Laser Mode Engineering and Waveguide Design” (DOI) (IEEEXplore) (Abstract, amended version) (Presentation Slides)