Fig. 1. Simulation structure of GO/AuNRs composite substrate

Fig. 2. Polarization orientation of light source and the square of electric-field intensity |E|2 distribution of composite substrate in XZ plane. (a) Polarization orientation of linearly polarized light; (b) polarization direction of radially polarized light; (c) the square of electric-field intensity |E|2 distribution of GO/single-AuNR composite substrate excited by linearly polarized light; (d) logarithmic plots of the square of electric-field intensity |E|2 distribution of GO/single-AuNR composite su

Fig. 3. Variation in |E|2 with aspect ratio of AuNR in XZ plane

Fig. 4. |E|2 distributions of composite substrate with different thicknesses of GO in XZ plane. (a) 0 nm; (b) 1 nm; (c) 2 nm; (d) 3 nm; (e) 4 nm; (f) 5 nm; (g) variation in |E|2 with thickness of GO

Fig. 5. Logarithmic plots of |E|2 of different composite substrates in XZ plane. (a) GO/dual-AuNRs composite substrate; (b) GO/three-AuNRs composite substrate; (c) GO/four-AuNRs composite substrate

Fig. 6. Variation in |E|2 with distance between Au nanorods in XZ plane

Fig. 7. Arrangements of AuNRs and |E|2 distribution in XZ plane. (a) Equilateral triangular arrangement of three-AuNRs and square arrangement of four-AuNRs; (b) |E|2 distribution of triangular arrangement of AuNRs; (c) |E|2 distribution of square arrangement of AuNRs

Table 1. SERS enhancement factor of composite substrate