Brillouin Scattering: Fundamentals, Devices, and Emerging Applications

Brillouin scattering, arising from the interaction between light and acoustic phonons, provides a powerful mechanism for probing, manipulating, and generating coherent optical and acoustic waves. As a fundamental inelastic light-scattering process, it bridges photonics, phononics, nonlinear optics, materials science, sensing, and precision measurement. Recent advances in micro- and nanophotonic structures, integrated waveguides, optical fibers, crystalline media, and free-space resonators have significantly expanded the capabilities of Brillouin-based science and technology.In fundamental research, Brillouin scattering enables the study of photon–phonon coupling, acoustic-wave dynamics, optomechanical interactions, linewidth narrowing, frequency shifting, and noise suppression. In applied photonics, it has become a key physical process for narrow-linewidth laser generation, microwave photonics, distributed fiber sensing, optical signal processing, frequency combs, nonreciprocal devices, quantum information, and high-power coherent light sources. In materials and precision measurement, Brillouin spectroscopy and imaging offer non-contact approaches for characterizing mechanical properties, stress, elasticity, viscosity, and thermal behavior across solids, liquids, biological tissues, and engineered materials.

This Special Topic aims to highlight recent progress in the physics, devices, systems, and applications of Brillouin scattering. It welcomes contributions ranging from fundamental mechanisms and advanced material platforms to emerging Brillouin photonic devices and interdisciplinary applications. Both theoretical, numerical, and experimental studies, as well as research and review articles, are encouraged.