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arXiv · 2204.05528

Organic metallic epsilon-near-zero materials with large ultrafast optical nonlinearity

Qili Hu·Xinlan Yu·Hongqi Liu·Jiahuan Qiu·Wei Tang·Sen Liang·Linjun Li·Miao Du·Junjun Jia·Hui Ye
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Abstract

Epsilon-near-zero (ENZ) materials have shown significant potential for nonlinear optical applications due to their ultrafast hot carriers and consequent optical nonlinearity enhancement. Modified poly(3,4-ethylenedioxythiophene) (PEDOT) films show metallic characteristics and a resultant ENZ wavelength near 1550nm through polar solvent treatment and annealing. The metallic PEDOT film exhibits an intrinsic optical nonlinear response that is comparable to gold and 100-fold higher than typical inorganic semiconductor ENZ materials due to π-conjugated delocalized electrons. Hot carriers generate a 22-fold increase in the optical nonlinearity coefficient of metallic PEDOT films at 1550 nm. Hot holes in metallic PEDOT films have a smaller enhancement multiple of carrier temperature and a longer relaxation time than hot electrons in inorganic ENZ materials due to the larger imaginary permittivity and hot-phonon bottleneck for carrier cooling. Our findings suggest that π-conjugated ENZ polymer may have unique ultrafast and nonlinear optical properties compared to inorganic ENZ materials, enabling new possibilities in on-chip nanophotonic devices, nonlinear optics, and plasmonics.

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Qili Hu, Xinlan Yu, Hongqi Liu, Jiahuan Qiu, Wei Tang, Sen Liang, Linjun Li, Miao Du, Junjun Jia, Hui Ye. 2022-10-05. Organic metallic epsilon-near-zero materials with large ultrafast optical nonlinearity. https://arxiv.org/abs/2204.05528

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