Interplay of Phonon and Optical Cavity Effects in Layered Semiconductor Materials

Abstract Optical cavities can be used to tailor photon-phonon coupling due to the spatial overlap of photon and phonon fields and selective enhancement of photon or phonon resonance excitation. However, there has been limited focus on understanding the influence of optical cavities on lattice phonon excitation, since they are typically considered as inherent element excitation in solids and challenging to manipulate. Here we demonstrate a strong interplay of phonon and optical cavity effects mediated by one-dimensional periodic electronic states in layered semiconductor materials (LSMs). LSM multilayers act as naturally occurring optical cavities. This results in tunable layer-breathing phonon excitation, dependent on the incident light wavelength, number of layers and mismatch of refractive index between LSM and underlying substrate. Our study reveals the impact of spatially coherent overlap between photon and phonon fields on phonon excitation, and paves the way for optical modulators and signal processing via photon-phonon cavity engineering.