针对石墨烯基的折射率传感系统中存在的大量程和高测量灵敏度无法兼得且仅能实现相对折射率测量的问题,提出了一种基于全内反射式的大量程绝对折射率测量方法。该方法仅通过一维线性运动,实现了大范围角度的精确调控。利用光学4f系统,保证了采样点位置不随入射角的变化而变化。不同入射角下的扫描测量方法的折射率测量范围理论上可以达到1~1.5168,通过对不同质量分数的氯化钙溶液的折射率进行测量,从实验上获得7.203×10 ^-4 RIU的测量灵敏度。

In a graphene-based refractive index sensing system, the large range and high measurement sensitivity cannot be achieved simultaneously, and only the relative refractive index can be measured. In this study, a large-range absolute refractive index measurement method based on total internal reflection is proposed, which realizes the accurate regulation of a wide range of angles only through one-dimensional linear motion. The optical 4f system ensures that the position of the sampling point does not change with the incident angle. By the scanning measurement method at different incident angles, the measurement range of the refractive index can reach 1--1.5168 in theory. Through the refractive index measurement of calcium chloride solution with different mass fraction, the measurement sensitivity obtained in experiments is 7.203×10 ^-4 RIU.