Mode-selective control in broadband stimulated Raman spectroscopy via chirped-gated detection

Abstract

Conventional narrowband femtosecond stimulated Raman spectroscopy (SRS) implementations often rely on complex optical parametric systems or static narrowband filters, limiting vibrational mode tunability and operational simplicity. Here, we present a chirped-gated SRS (CG-SRS) technique that enables mode-selective control across a broadband vibrational spectrum. By applying a controlled chirp to the broadband probe pulse, CG-SRS establishes a time–frequency mapping mechanism that allows distinct vibrational modes to be selectively addressed and enhanced at different probe delays under single-wavelength excitation. This method enables dynamic enhancement or suppression of individual Raman modes without filter-based tuning. Using ethanol as a model system, we demonstrate selective enhancement of individual vibrational contributions within the C–H stretching region and further achieve dynamic switching from the 980 to the 2900 cm−1 via time-delay control. Additional validation is carried out using liquid water and diamond. CG-SRS provides a powerful tool for mode-selective vibrational control and offers a promising reference for selective excitation in chemical reactions and biomedical imaging.