New Model Incorporates Evanescent Modes in Scattering Matrix for Disordered Media Wavefront Shaping
Researchers have developed an open-source scalar wave transport model that extends the generalized scattering matrix to include evanescent wave modes alongside propagating modes in disordered media. The work, accepted in Physical Review Research, uses the Kirchhoff-Helmholtz boundary integral formulation and Green's function perturbation method to generalize the conventional Fisher-Lee relations. The model enables optimal wavefront shaping for focusing through disordered media and may serve as a practical tool for the broader wavefront shaping research community.
A research team has published an open-source computational framework for modeling the generalized scattering matrix (S matrix) of disordered media, extending classical theory to incorporate evanescent wave modes in addition to propagating modes. The approach combines the scalar Kirchhoff-Helmholtz boundary integral formulation with the Green's function perturbation method, allowing the Fisher-Lee relations—previously limited to propagating modes—to be generalized. The resulting S matrix is shown to satisfy generalized unitarity and reciprocity relations, and is demonstrated for a two-dimensional disordered waveguide geometry. Using the generalized transmission matrix extracted from the S matrix, the authors compute an optimal phase-conjugate wavefront for focusing onto an evanescent mode. A key finding is the demonstration of a universal transmission value of 2/3 for such optimal phase-conjugate wavefronts in the context of evanescent mode focusing through diffusive disorder. The work is accepted for publication in Physical Review Research, and the accompanying code is intended as a resource for wavefront shaping researchers studying wave transport in complex media.
What's missing
The study does not discuss experimental validation of the model against physical measurements; it is purely computational. The scope of applicability beyond 2D scalar wave systems (e.g., 3D geometries or vector/electromagnetic waves) is not addressed. Computational cost and scalability of the framework for large or highly scattering systems are not characterized.
What different sources said
- arXiv physicsCenter
Modeling scattering matrix containing evanescent modes for wavefront shaping applications in disordered media
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