Far-field transient absorption nanoscopy with sub-50 nm optical super-resolution

作者：Yali Bi, Chi Yang, Lei Tong, Haozheng Li, Boyu Yu, Shuai Yan, Guang Yang, Meng Deng, Yi Wang, Wei Bao, Lei Ye, Ping Wang · 发表于：Optica · 年份：2020 · DOI：10.1364/optica.402009 · 被引用次数：18 · 研究领域：Advanced Fiber Laser Technologies、Advanced Fluorescence Microscopy Techniques、Near-Field Optical Microscopy

Nanoscopic imaging or characterizing is the mainstay of the development of advanced materials. Despite great progress in electronic and atomic force microscopies, label-free and far-field characterization of materials with deep sub-wavelength spatial resolution has long been highly desired. Herein, we demonstrate far-field super-resolution transient absorption (TA) imaging of two-dimensional material with a spatial resolution of sub-50 nm. By introducing a donut-shaped blue saturation laser, we effectively suppress the TA transition driven by near-infrared (NIR) pump–probe photons, and push the NIR-TA microscopy to sub-diffraction-limited resolution. Specifically, we demonstrate that our method can image the individual nano-grains in graphene with lateral resolution down to 36 nm. Further, we perform super-resolution TA imaging of nano-wrinkles in monolayer graphene, and the measured results are very consistent with the characterization by an atomic force microscope. This direct far-field optical nanoscopy holds great promise to achieve sub-20 nm spatial resolution and a few tens of femtoseconds temporal resolution upon further improvement and represents a paradigm shift in a broad range of hard and soft nanomaterial characterization.