Fig. 2
From: Creating topological exceptional point by on-chip all-dielectric metasurface
Numerical analysis of the EP with on-chip all-dielectric topological metasurfaces. a The complex refractive indices of Si and Al. The green dashed line marks the operating wavelength of 525 nm. Here, n and k denote the real and imaginary parts of the refractive index, respectively. b Schematic illustration of the on-chip all-dielectric metasurface with topological meta-atoms. c Perspective view of the Si meta-atom positioned on the top of a Si3N4 waveguide and SiO2 substrate. d Top view of the designed dielectric meta-atom. The dimensions are L2 = 440 nm, W = 70 nm, P = 500 nm. e, f Simulated extraction coefficients for LCP and RCP, covering the parameter space of L1 ∈ [200 nm, 300 nm] and d ∈ [50 nm, 150 nm]. An EP is obtained at (L1, d) = (250 nm, 90 nm) in LCP. g Perspective view of the meta-atom with a rotation angle θ. h, i Theoretical PB phase distributions for the on-chip metasurface with θ ∈ [0, 2π]
