Abstract The nonlinear optical properties of single layer graphene are studied via Z-scan. The measurements are carried out at 1045 nm with a 360 femtosecond highly stable Yb doped mode-locked fiber laser. Under laser illumination single-layer graphene exhibits both a transmittance increase due to saturable absorption and a nonlinear phase-shift due to nonlinear refraction. The nonlinear refraction measurements were carried out from 0.5 to 8 GW/cm2 revealing an expected irradiance-dependent nonlinear refraction. An effective nonlinear refractive index coefficient n I is used to describe this and discriminate it from the conventional n 2 coefficient usually measured by Z-scan. The saturation level of the nonlinear phase-shift where the nonlinear response becomes irradiance dependent is deduced from the experimental data.

中文翻译：

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直接观察 CVD 单层石墨烯中辐照度相关的非线性折射

摘要 通过Z-scan研究了单层石墨烯的非线性光学特性。使用 360 飞秒高度稳定的掺镱锁模光纤激光器在 1045 nm 处进行测量。在激光照射下，单层石墨烯表现出由于饱和吸收而导致的透射率增加和由于非线性折射而导致的非线性相移。非线性折射测量从 0.5 到 8 GW/cm2 进行，揭示了预期的辐照度相关非线性折射。一个有效的非线性折射率系数 n I 用于描述这一点，并将其与通常通过 Z 扫描测量的常规 n 2 系数区分开来。从实验数据推导出非线性响应变得与辐照度相关的非线性相移的饱和水平。