Phase-optimization wavefront shaping simulations in two-dimensional scattering media based on Maxwell's equations

Abstract

Wavefront shaping techniques allow one to focus light inside and through turbid media. In order to gain a better understanding how light evolves inside a scattering random medium while shaping the incident wavefront, it is beneficial to know the electromagnetic field within the entire medium, which is difficult to achieve in experiments. Here we investigate wavefront shaping techniques with numerical simulations based on Maxwell’s equations to examine various effects of wave propagation in randomly scattering media. First, we calculate numerically monochromatic plane wave solutions for a given scattering medium for different incident k-vectors. With these plane wave solutions we are able to simulate complex-shaped incident wavefronts impinging on the scattering medium. This enables us to scan and tilt the incident complex wavefront after solving Maxwell’s equations and to examine the electromagnetic field inside the medium. Due to the fact that we have access to the electromagnetic field of the plane wave illumination from different angles, it is easy to phase-optimize an incident wavefront by conjugating the known phase at a certain location. Because of the separate calculation of the plane wave solutions and the possibility to simulate different incident wavefronts by superimposing these plane wave solutions, our method is very dynamic and versatile. In summary, our simulation approach contributes to the understanding of light propagation in strongly scattering media such as biological tissue and to the improvement of medical imaging techniques.