2024-01-04 コロンビア大学
◆この発見は、物質を光で変更する新しい可能性を示唆しています。今後は、この手法を用いてhBNや同様の材料を光で変更する方法を探求する予定です。
＜関連情報＞
- https://www.engineering.columbia.edu/news/laser-driving-2d-material
- https://www.nature.com/articles/s41467-023-43501-x
六方晶窒化ホウ素における光子増強非線形性 Phonon-enhanced nonlinearities in hexagonal boron nitride
Jared S. Ginsberg,M. Mehdi Jadidi,Jin Zhang,Cecilia Y. Chen,Nicolas Tancogne-Dejean,Sang Hoon Chae,Gauri N. Patwardhan,Lede Xian,Kenji Watanabe,Takashi Taniguchi,James Hone,Angel Rubio & Alexander L. Gaeta
Nature Communications Published:24 November 2023
DOI:https://doi.org/10.1038/s41467-023-43501-x
Abstract
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.
