Fig. 1. The schematic diagram of graphene-black phosphorus（G-BP）heterostructure SPP sensor

Fig. 2. The absorption of SPP device with different materials

Fig. 3. The absorption of G-BP SPP sensor and the field distributions at resonance wavelengths

Fig. 4. The absorption spectra of G-BP device with various grating widths and periods

Fig. 5. The absorption spectra of G-BP device with various spacer thickness

Fig. 6. Absorption spectra of the SPP device covered with（dashed lines）and without（solid lines）8 nm-thick PEO molecular