Raman Scattering under Strong Vibration-Cavity Coupling

Strong\ncavity coupling can have profound effects on fundamental\nmaterial properties. In this work, we examine the Raman scattering\nresponse of a poly­(methyl methacrylate) (PMMA) carbonyl band under\nvibrational strong coupling in a Fabry–Pérot cavity.\nCollecting Raman scattering spectra in a cross-sectional geometry\nallows polarization-based discrimination between the cavity-modified\nand conventional bulk response. In this system, strong coupling reveals\nitself by a softening of the blue side of the Raman scattering feature\nand a small dip near the fundamental vibrational frequency. These\ncoupling-induced features are due to the upper and lower polaritons,\nwhich disperse over the collection angle of the microscope objective.\nControl measurements of detuned and half-cavities confirm that the\nfeatures originate from strong coupling. Modeling of this response\nis carried out, taking these issues into account and provide reasonable\nagreement to experiment.