Fig. 3: Experimental characterization of the properties of CEMs.
From: Magnetically controllable multimode interference in topological photonic crystals
a Photograph of the experimental setup. The YIG rods with a height of 6 mm are sandwiched by two aluminum plates to construct a topological photonic crystal waveguide with lattice constant \(a=16{\rm{mm}}\). b S21 (S12) is the measured transmission spectrum at point S (P) when the point source is placed on the point P (S) shown in Fig. 2a. The selective measurement of mode 1 (c) and mode 2 (d) at different position of the waveguide. The color map is obtained from experiment data, while the gray area, green, and blue dot lines are the numerical results
