Stimulated Raman scattering microscopy: fundamentals, instrumentation, and chemical imaging applications

Stimulated Raman scattering (SRS) microscopy is a fast Raman imaging technique that combines the molecular specificity of vibrational spectroscopy with the high spatial resolution and speed of laser-scanning microscopy. Building on the historical development of Raman and coherent Raman scattering (CRS) theories, advances in ultrafast lasers, modulation schemes, and detection electronics over the past 2 decades have transformed SRS from a laboratory curiosity into a practical platform for chemical imaging. This review article provides an integrated overview of the fundamentals of Raman spectroscopy and SRS microscopy, and presents the architecture of modern SRS instruments, including single-band and hyperspectral designs, contrast mechanisms, and the use of Raman probes. It also reviews recent technological progress in fiber laser sources, denoising and high-sensitivity detection schemes, hybrid and endoscopic SRS implementations, and emerging quantum-enhanced SRS (QE-SRS) approaches that aim to push sensitivity beyond classical limits. On the applications side, this review highlights label-free metabolic imaging at the single-cell level, bioorthogonal Raman tagging of drugs and metabolites, and tissue studies that link lipid metabolism to disease. A dedicated section summarizes the development of stimulated Raman histology (SRH) for intraoperative rapid diagnosis and surgical guidance, including deep-learning convolutional neural network (CNN) and artificial intelligence (AI) models that enable near real-time interpretation of fresh brain and other neoplastic tissues. Additional topics covered in this review include drug delivery, environmental and materials science, analysis of micro- and nanoplastic particles (MNPs), and imaging of fungal, bacterial, and plant systems. Taken together, the studies summarized in this review show that SRS microscopy has matured into a versatile and reliable modality for non-fluorescent chemical imaging across biology, medicine, and materials science, while continued progress in laser sources, detection, computation, and probe design is expected to further expand its capabilities and impact.