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Phonon-enhanced nonlinearities in hexagonal boron nitride

Polar crystals can be driven into collective oscillations by optical fields tuned to precise resonance frequencies. As the amplitude of the excited phonon modes increases, novel processes scaling non-linearly with the applied fields begin to contribute to the dynamics of the atomic system. Here we s...

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Detalles Bibliográficos
Autores principales: Ginsberg, Jared S., Jadidi, M. Mehdi, Zhang, Jin, Chen, Cecilia Y., Tancogne-Dejean, Nicolas, Chae, Sang Hoon, Patwardhan, Gauri N., Xian, Lede, Watanabe, Kenji, Taniguchi, Takashi, Hone, James, Rubio, Angel, Gaeta, Alexander L.
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Nature Publishing Group UK 2023
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10673846/
https://www.ncbi.nlm.nih.gov/pubmed/38001087
http://dx.doi.org/10.1038/s41467-023-43501-x
Descripción
Sumario:Polar crystals can be driven into collective oscillations by optical fields tuned to precise resonance frequencies. As the amplitude of the excited phonon modes increases, novel processes scaling non-linearly with the applied fields begin to contribute to the dynamics of the atomic system. Here we show two such optical nonlinearities that are induced and enhanced by the strong phonon resonance in the van der Waals crystal hexagonal boron nitride (hBN). We predict and observe large sub-picosecond duration signals due to four-wave mixing (FWM) during resonant excitation. The resulting FWM signal allows for time-resolved observation of the crystal motion. In addition, we observe enhancements of third-harmonic generation with resonant pumping at the hBN transverse optical phonon. Phonon-induced nonlinear enhancements are also predicted to yield large increases in high-harmonic efficiencies beyond the third.