In this work, the electrical tuning of the fifth‐order nonlinear absorption of antimony‐doped tin oxide (ATO) by ionic liquid gating is demonstrated. The pristine ATO film exhibits two‐photon‐induced excited‐state absorption (2PA‐ESA) with laser excitation at 1030 nm. The fifth‐order nonlinear absorption coefficient (γ_eff) of the ATO film can be monotonically modified in the range of 0.51 to 3.46 cm³ GW⁻² by varying the sample bias, with a maximum enhancement factor of 6.8. The fundamental processes occurring during electrical tuning are revealed. The electrostatic and electrochemical capacitance is responsible for the modification in the number of free carriers in the conduction band of ATO. The electrical modulation of the nonlinear absorption of the ATO is ascribed to the voltage‐dependent diameter of the undepleted core of ATO. A smaller voltage results in the charging of ATO and a larger undepleted core, and consequently the size of the active component for 2PA‐ESA is larger. The electrochemical capacitance results from the chemisorption of H⁺ and OH⁻ on the surface of the ATO, the larger water content in the ionic liquid affording a larger modulation range for the number of free carriers and the γ_eff.

中文翻译：

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掺锑氧化锡五阶光学非线性的电调谐

在这项工作中，演示了离子液体门控对锑掺杂氧化锡（ATO）的五阶非线性吸收的电调谐。原始的ATO膜在1030 nm的激光激发下表现出双光子诱导的激发态吸收（2PA-ESA）。可以在0.51至3.46 cm ³  GW ^-2的范围内单调修改ATO膜的五阶非线性吸收系数（_γeff）通过改变采样偏置，最大增强因子为6.8。揭示了电调谐过程中发生的基本过程。静电和电化学电容负责改变ATO导带中自由载流子的数量。ATO非线性吸收的电调制归因于ATO未耗尽磁芯的电压相关直径。较小的电压会导致ATO充电，而未耗尽的磁芯也会变大，因此2PA-ESA有源组件的尺寸会更大。从H的化学吸附的电化学电容结果⁺和OH ^-在ATO，在离子液体中，得到自由载流子的数量和γ较大调制范围较大的水含量的表面_EFF。