Theory and Modeling of Optomechanics in Charge Density Wave Materials

Novel materials with large optomechanical coupling coefficients are useful both for the exploration of fundamental light-matter interactions, and for the application of their nonlinear response properties in nanoscale devices. Motivating and parameterizing simple phenomenological models of the dominant physics of such materials will provide an important connection between expensive first-principles calculations, and experimental observables. Using 1T-TaS2 as a case study, we develop a general model for studying the coupling between phonons and change in polarizability. This model is successfully applied to the optomechanical response of the commensurate charge density wave (CDW) phase of 1T-TaS2, where we can provide a simple physical explanation for the observation of the coherent 2.4 THz CDW amplitude mode that is observed in this system [1]. This model is generally applicable to materials where a change in symmetry is accompanied by a change in the polarizability of a system.