Fig. 2. Topological boundary modes for different values of PSH and VH perturbations.

(A) Purely PSH boundary modes between two domains with θ = 0 and θ′ = π. (B) Mixed PSH-VH boundary modes for θ = π/6 and θ′ = 7π/6 (right side), θ = −π/6 and θ′ = 5π/6 (left side). (C) Mixed PSH-VH boundary modes for θ = π/4 and θ′ = 5π/4 (right side), θ = −π/4 and θ′ = 3π/4 (left side). Insets: The far field polarization profiles for the boundary modes.