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arXiv · 2411.10160

Phonon-Polaritons in Non-Centrosymmetric Systems: Theory of Terahertz Pump-Optical Probe Spectroscopy

Niccolò Sellati·Jacopo Fiore·Stefano Paolo Villani·Lara Benfatto·Mattia Udina
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Abstract

Hybrid lattice-light modes, known as phonon-polaritons, represent the backbone of advanced protocols based on THz pumping of infrared modes. Here we provide a theoretical framework able to capture the different roles played by phonon-polaritons in experimental protocols based either on Raman-like pump and probe schemes, typical of four-wave-mixing processes, or on THz pump-visible probe three-wave mixing protocols. By using a many-body description of the nonlinear optical kernel, along with a perturbative solution of nonlinear Maxwell's equations, we highlight the advantages of exploiting broadband THz pumps to enlarge the phase space of the phonon-polariton dispersion accessible in a single experiment. Besides providing a quantitative description of existing and future experiments, our results offer a general framework for the theoretical modeling of the hybridization between light and lattice degrees of freedom in time-resolved experiments.

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Niccolò Sellati, Jacopo Fiore, Stefano Paolo Villani, Lara Benfatto, Mattia Udina. 2024-11-15. Phonon-Polaritons in Non-Centrosymmetric Systems: Theory of Terahertz Pump-Optical Probe Spectroscopy. https://doi.org/10.1038/s41535-025-00761-8

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