Label‐free superresolution effect of nonlinear reverse saturation absorption (NRSA) thin films was investigated through difference method, where a subdiffraction‐limit spot signal was constructed by intensity subtraction of two spots obtained under different laser intensities. By using annealed InSb films as the NRSA thin films, we experimentally obtained the subdiffraction‐limit spot signal, and the optimal reduction ratio was approximately 52.5% of the original spot. Experimental results agreed well with theoretical simulations. The simulation results of a 9‐point array sample showed the capability to achieve nonfluorescence superresolution imaging using the NRSA effect.

中文翻译：

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基于差分法的非线性反向饱和吸收薄膜的无标记超分辨率效应

通过差分法研究了非线性反向饱和吸收 (NRSA) 薄膜的无标记超分辨率效应，其中通过在不同激光强度下获得的两个光点的强度相减来构建亚衍射极限光点信号。通过使用退火的 InSb 薄膜作为 NRSA 薄膜，我们通过实验获得了亚衍射极限光斑信号，最佳缩小率约为原始光斑的 52.5%。实验结果与理论模拟非常吻合。9 点阵列样品的模拟结果显示了使用 NRSA 效应实现非荧光超分辨率成像的能力。