Fig. 1. MIM waveguide structure with asymmetric circular resonant cavity. (a) Schematic of three-dimensional structure; (b) schematic of two-dimensional structure in x-y plane

Fig. 2. Comparison of transmission spectra of filters with different MIM structures

Fig. 3. Electric field density distributions of MIM waveguides with asymmetric circular and semi-circular cavities under different operating wavelengths. (a) 620 nm; (b) 1070 nm; (c) 1765 nm; (d) 650 nm; (e) 1550 nm; (f) 2380 nm

Fig. 4. Effect of radius of circular resonant cavity on light-transfer characteristics when D=200 nm and t=50 nm. (a) Transmission spectra under different r; (b) relationship between r and stopband width; (c) relationship between r and steepness of rising and falling edges

Fig. 5. Effect of distance between circular resonant cavities on light-transfer characteristics when r=100 nm and t=50 nm. (a) Transmission spectra under different D; (b) relationship between D and its stopband width; (c) relationship between D and steepness of rising and falling edges

Fig. 6. Structural diagrams and transmission spectra of MIM when D=200 nm, r=100 nm, and t=50 nm. (a)-(c) Structural diagrams; (d)-(f) transmission spectra