Optical Self-Trapping and Nonlinear Light-Matter Interactions in Biological Soft Matter

TL;DR

This review discusses nonlinear optical phenomena in biological soft matter, highlighting recent advances in self-trapping, waveguiding, and complex light-matter interactions for biomedical applications.

Contribution

It extends previous studies by exploring complex nonlinear regimes and phenomena in biological media, emphasizing potential biomedical and photonic device applications.

Findings

Observation of structured beam propagation in biological media

Identification of thermally driven nonlinear responses in biomolecular solutions

Demonstration of quasi-waveguide formation in biological tissues

Abstract

Low-scattering, deep-penetration light transport in biological media remains a pivotal challenge for biophotonic technologies, including biomedical imaging, optical diagnostics, and photodynamic therapy. This review builds upon and extends our earlier studies of nonlinear optical self-trapping and optically induced waveguiding in biological suspensions, such as human erythrocytes and cyanobacteria, where light-matter coupling is governed by optical-force-mediated particle redistribution. Recent progress has revealed increasingly rich and complex regimes, including the propagation and nonlinear self-action of structured (vortex) beams in biological environments, as well as nonlinear responses dominated by thermally driven mechanisms in absorptive biomolecular solutions (e.g., heme and chlorophyll). We place particular emphasis on distinctive nonlinear phenomena observed in these systems, including spatial self-phase modulation, optical-force-induced sculpturing of effective energy landscapes, and quasi-waveguide formation in soft, heterogeneous biological media. We conclude by highlighting emerging opportunities to harness these nonlinear behaviors for deep-tissue imaging, label-free biosensing, and the realization of biocompatible photonic structures and devices assembled directly from living or hybrid biological matter.