Experimental Characterization Techniques for On‐Chip Stimulated Brillouin Scattering: Principles, Platforms, and Perspectives

ABSTRACT

Stimulated Brillouin scattering (SBS), a third‐order nonlinear optical effect, arising from photon‐phonon interactions, exhibits one of the lowest thresholds among nonlinear processes and has recently emerged as a powerful mechanism in integrated photonics. Owing to its unique opto‐acoustic coupling, on‐chip SBS enables a variety of functionalities, including narrow‐linewidth lasers, microwave photonic filtering, optical delay, optical amplification, optical recurrent neural networks, optical storage, phonon lasing, and ultra‐high‐purity RF signal generation. Furthermore, the integration of SBS with Kerr nonlinearity, topological photonics, and exceptional points has enabled new phenomena such as broadband platform solitons, robust directional Stokes light transmission, and high‐precision gyroscopes. Since its first demonstration in chalcogenide waveguides, on‐chip SBS has been realized in diverse material platforms, including silicon, silicon nitride, rare‐earth‐ion‐doped silicon nitride, and lithium niobate, each requiring distinct characterization approaches. In this review, we introduce the fundamental principles and classifications of SBS, followed by a comprehensive overview of seven representative experimental Configurations for on‐chip SBS characterization. Their operating principles, advantages, limitations, and applicable scenarios are systematically compared. Finally, we discuss emerging opportunities for SBS in topological photonic platforms toward robust and quantum‐coherent photon‐phonon functionalities.