Pablo Jara | Searcharxiv

arXiv2026

Universal compression of wave fields in weakly scattering media

Advances in computational methods have made full-wave simulations in large disordered media increasingly feasible, but the resulting field data, scaling with the cube of the ratio of system size to wavelength, creates a severe storage and post-processing bottleneck. Generic compression methods are sample-specific and preclude operations on compressed data. We introduce OSCAR (On-Shell Compression And Reconstruction), a physics-based lossy compression scheme for weakly scattering media. OSCAR exploits the universal confinement of the Fourier representation of wave fields to a thin dispersion shell, a direct consequence of wave propagation when the scattering mean free path significantly exceeds the wavelength. The resulting compression ratio reflects two distinct scale separations: on-shell confinement due to weak scattering, and the excess Fourier-space volume introduced by sub-wavelength discretization of the scatterers. Crucially, second-order quantities such as intensity, correlations, and (optical) sensitivity can be computed via convolution entirely in compressed space and remain accurate even when individual field reconstruction incurs appreciable error, because coherent interference between independently compressed fields is preserved. Numerical simulations of electromagnetic waves in 2D and 3D confirm compression ratios up to ${\sim}380\times$ with sub-percent field error, enabling routine ensemble studies at scales relevant to biomedical optics, seismology, and underwater acoustics.

physics.optics↗

arXiv2025

Harnessing coherent-wave control for sensing applications

Imaging techniques such as functional near-infrared spectroscopy (fNIRS) and diffuse optical tomography (DOT) achieve deep, non-invasive sensing in turbid media, but they are constrained by the photon budget. Wavefront shaping (WFS) can enhance signal strength via interference at specific locations within scattering media, enhancing light-matter interactions and potentially extending the penetration depth of these techniques. Interpreting the resulting measurements rests on the knowledge of optical sensitivity - a relationship between detected signal changes and perturbations at a specific location inside the medium. However, conventional diffusion-based sensitivity models rely on assumptions that become invalid under coherent illumination. In this work, we develop a microscopic theory for optical sensitivity that captures the inherent interference effects that diffusion theory necessarily neglects. We analytically show that under random illumination, the microscopic and diffusive treatments coincide. Using our microscopic approach, we explore WFS strategies for enhancing optical sensitivity beyond the diffusive result. We demonstrate that the input state obtained through phase conjugation at a given point inside the system leads to the largest enhancement of optical sensitivity but requires an input wavefront that depends on the target position. In sharp contrast, the maximum remission eigenchannel leads to a global enhancement of the sensitivity map with a fixed input wavefront. This global enhancement equals to remission enhancement and preserves the spatial distribution of the sensitivity, making it compatible with existing DOT reconstruction algorithms. Our results establish the theoretical foundation for integrating wavefront control with diffuse optical imaging, enabling deeper tissue penetration through improved signal strength in biomedical applications.

physics.optics↗