Fig. 1. Preparation flow chart of AG/GE/AG substrate

Fig. 2. Morphology characterization graphs of AG/GE/AG substrate. (a) SEM characterization; (b) TEM characterization; (c)(d) EDS characterization of Ag and C

Fig. 3. COMSOL simulation diagrams of AG/GE/AG substrate. (a) Ideal model; (b) abstract model based on TEM image

Fig. 4. Raman characterization results of AG/GE/AG substrates. (a) Raman spectrum of graphene and AG/GE/AG substrate; (b)(c) Raman mapping test chart of AG/GE/AG substrate; (d) heat map of 2D peak intensity of AG/GE/AG substrate

Fig. 5. Raman diagrams of Rhodamine 6G and crystal violet molecules. (a) Rhodamine 6G; (b) crystal violet

Fig. 6. Results of repeatability test. (a) Raman signal before cleaning; (b) Raman signal after cleaning