Fig. 1. Three-layer structure of BK7-graphene-sample to be tested

Fig. 2. Reflectance curves. (a) Three-layer structure of BK7-graphene-sample to be tested; (b) two-layer structure of BK7-sample to be tested

Fig. 3. Accurate adjustment devices for incident light angle of optical reflection system. (a) Before angle adjustment; (b) after angle adjustment

Fig. 4. Large range absolute refractive index sensing system based on graphene. (a) Before angle adjustment; (b) after angle adjustment

Fig. 5. Reflection curves of materials with different refractive indices

Fig. 6. Correction schematic diagram

Fig. 7. Relationship between moving distance of translation table and refractive index

Fig. 8. Relationship between mass fraction of calcium chloride solution and refractive index