Fig. 3
FF GPs and field enhancement on the GSSDG. a Dispersion curves of the GPs on the GSSDG. The blue and green solid lines correspond to the real [Re(neff)] and imaginary [Im(neff)] part of the effective index retrieved from Eq. (3), respectively, while the blue and green rhombuses are gotten from numerical simulations. b Absorption spectrums with grating substrate (red line) and pure silicon substrate without the grating (blue line). c The normalized |E| distributions of the fundamental GPs mode at 28.62 μm. The black dashed lines outline the silicon layer. d The excitation wavelength of the fundamental GPs mode versus the grating period. The blue line is retrieved from Eq. (6), and the red rhombuses are from numerical simulation. In b and c, P is set as 4 μm. All the simulation results are retrieved by the commercial software Lumerical FDTD Solutions