Abstract Broadband dispersion free, large and ultrafast nonlinear material platforms comprise the essential foundation for the study of nonlinear optics, integrated optics, intense field optical physics, and quantum optics. Despite substantial research efforts, such material platforms have not been established up to now because of intrinsic contradictions between large nonlinear optical coefficient, broad operating bandwidth, and ultrafast response time. In this work, a broadband dispersion free, large and ultrafast nonlinear material platform based on broadband epsilon-near-zero (ENZ) material is experimentally demonstrated, which is designed through a novel physical mechanism of combining structural dispersion and material dispersion. The broadband ENZ material is constructed of periodically nanostructured indium tin oxide (ITO) films, and the structure is designed with the help of theoretical predictions combined with algorithm optimization. Within the whole broad ENZ wavelength range (from 1300 to 1500 nm), a wavelength-independent and large average nonlinear refractive index of −4.85 × 10−11 cm2/W, which is enlarged by around 20 times than that of an unstructured ITO film at its single ENZ wavelength, and an ultrafast response speed at the scale of Tbit/s are experimentally reached simultaneously. This work not only provides a new approach for constructing nonlinear optical materials but also lays the material foundation for the application of nanophotonics.

中文翻译：

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用于光子学的宽带无色散、大型和超快非线性材料平台

摘要 宽带无色散大型超快非线性材料平台是非线性光学、集成光学、强场光学物理和量子光学研究的重要基础。尽管进行了大量的研究，但由于非线性光学系数大、工作带宽宽和响应时间超快之间的内在矛盾，这种材料平台至今尚未建立。在这项工作中，实验证明了一种基于宽带 epsilon-near-zero (ENZ) 材料的宽带无色散、大型和超快非线性材料平台，该平台是通过结合结构色散和材料色散的新型物理机制设计的。宽带 ENZ 材料由周期性纳米结构的氧化铟锡 (ITO) 薄膜构成，并结合理论预测结合算法优化设计结构。在整个宽 ENZ 波长范围内（从 1300 到 1500 nm），与波长无关且大的平均非线性折射率为 -4.85 × 10-11 cm2/W，比非结构化 ITO 薄膜放大约 20 倍在其单一的 ENZ 波长下，同时通过实验达到了 Tbit/s 级的超快响应速度。该工作不仅为构建非线性光学材料提供了一种新途径，而且为纳米光子学的应用奠定了物质基础。与波长无关的大平均非线性折射率为 -4.85 × 10-11 cm2/W，比非结构化 ITO 薄膜在其单一 ENZ 波长下放大约 20 倍，并且在通过实验同时达到 Tbit/s。该工作不仅为构建非线性光学材料提供了一种新途径，而且为纳米光子学的应用奠定了物质基础。与波长无关的大平均非线性折射率为 -4.85 × 10-11 cm2/W，比非结构化 ITO 薄膜在其单一 ENZ 波长下放大约 20 倍，并且在通过实验同时达到 Tbit/s。该工作不仅为构建非线性光学材料提供了一种新途径，而且为纳米光子学的应用奠定了物质基础。