Theory of terahertz pump optical probe spectroscopy of phonon polaritons in noncentrosymmetric systems

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 Rama...

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Main Authors: Niccolò Sellati, Jacopo Fiore, Stefano Paolo Villani, Lara Benfatto, Mattia Udina
Format: Article
Language:English
Published: Nature Portfolio 2025-05-01
Series:npj Quantum Materials
Online Access:https://doi.org/10.1038/s41535-025-00761-8
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author Niccolò Sellati
Jacopo Fiore
Stefano Paolo Villani
Lara Benfatto
Mattia Udina
author_facet Niccolò Sellati
Jacopo Fiore
Stefano Paolo Villani
Lara Benfatto
Mattia Udina
author_sort Niccolò Sellati
collection DOAJ
description 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 discuss the limitations of all-optical four-wave mixing protocols and we highlight the advantages of exploiting broadband THz pumps to enlarge the phase space of the phonon polariton dispersion at low momenta 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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spelling doaj-art-0fb4ad1b820d4ea1987d5955eab4aac62025-08-20T02:10:48ZengNature Portfolionpj Quantum Materials2397-46482025-05-011011610.1038/s41535-025-00761-8Theory of terahertz pump optical probe spectroscopy of phonon polaritons in noncentrosymmetric systemsNiccolò Sellati0Jacopo Fiore1Stefano Paolo Villani2Lara Benfatto3Mattia Udina4Department of Physics, Sapienza University of RomeDepartment of Physics, Sapienza University of RomeDepartment of Physics, Sapienza University of RomeDepartment of Physics, Sapienza University of RomeDepartment of Physics, Sapienza University of RomeAbstract 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 discuss the limitations of all-optical four-wave mixing protocols and we highlight the advantages of exploiting broadband THz pumps to enlarge the phase space of the phonon polariton dispersion at low momenta 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.https://doi.org/10.1038/s41535-025-00761-8
spellingShingle Niccolò Sellati
Jacopo Fiore
Stefano Paolo Villani
Lara Benfatto
Mattia Udina
Theory of terahertz pump optical probe spectroscopy of phonon polaritons in noncentrosymmetric systems
npj Quantum Materials
title Theory of terahertz pump optical probe spectroscopy of phonon polaritons in noncentrosymmetric systems
title_full Theory of terahertz pump optical probe spectroscopy of phonon polaritons in noncentrosymmetric systems
title_fullStr Theory of terahertz pump optical probe spectroscopy of phonon polaritons in noncentrosymmetric systems
title_full_unstemmed Theory of terahertz pump optical probe spectroscopy of phonon polaritons in noncentrosymmetric systems
title_short Theory of terahertz pump optical probe spectroscopy of phonon polaritons in noncentrosymmetric systems
title_sort theory of terahertz pump optical probe spectroscopy of phonon polaritons in noncentrosymmetric systems
url https://doi.org/10.1038/s41535-025-00761-8
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