The correlation between electrical properties and surface plasmon resonance (SPR) wavelength was discussed using ITO grating coupler. ITO films were prepared on SiO\(_{2}\)/Si substrate by RF sputtering with thermal annealing, and the grating was directly fabricated on the sample surface by focused ion beam. Electron density and mobility were evaluated by fitting optical reflection spectra according to Drude model, and then SPR wavelength was estimated from the dispersion relation of surface plasmon. Characteristic SPR dip was observed in polarized reflection spectrum, however, measured wavelength was different from theoretically estimated value. The discrepancy was explained by introducing the assumption based on effective medium theory, in which the grating is assumed as a thin film with effective refractive index.

使用 ITO 光栅耦合器讨论了电特性与表面等离子体共振 (SPR) 波长之间的相关性。ITO薄膜制备在SiO \(_{2}\)/Si衬底通过RF溅射和热退火，通过聚焦离子束直接在样品表面制作光栅。根据Drude模型通过拟合光反射光谱来评估电子密度和迁移率，然后根据表面等离子体的色散关系估计SPR波长。在偏振反射光谱中观察到特征 SPR 下降，但是，测量波长与理论估计值不同。这种差异是通过引入基于有效介质理论的假设来解释的，其中光栅被假设为具有有效折射率的薄膜。