Refractive Index and Dispersion Measurement Principle with Polarization Change in Total Internal Reflection

• DOI: 10.3390/photonics11060505
• Publication Date: 2024-05-27T14:12:27Z
• Authors: Jyun-Ping Chang; Cheng-Mu Tsai; Jun-Hong Weng; Pin Han
• Keywords: 0301 basic medicine; 03 medical and health sciences; polarization change; total internal reflection; Applied optics. Photonics; material dispersion; refractive index measurement; TA1501-1820

Refractive index measurements have been an important task for a long time because that index plays an essential role in describing the optical properties of a material. Many methods have been developed to perform that task. Some of them use interferometry to achieve high precision. However, these configurations are complicated. Some measure the critical angle using simple structures, but their accuracy is unsatisfactory because it is difficult to judge the exact critical angle with intensity variations. Here, we propose several new schemes based on measuring the polarization change in the total internal reflection. The proposed method has the merits of simple structure and easy incident angle determination that gives the maximum phase change. Additionally, it is possible to find the material dispersion by measuring the wavelength dependence of the polarization ellipticity. Some useful formulas relating the refractive index to the maximum phase change are obtained. This work can provide valuable alternatives for refractive index measurement.