Fig. 1. Structure of the nonreciprocal single channel filter

Fig. 2. Dispersion curve of the waveguide 1

Fig. 3. Dispersion curve of waveguide 2

Fig. 4. Electric field distribution of electromagnetic waves in the resonator. (a) Frequency is 0.4002; (b) frequency is 0.4106

Fig. 5. Forward and backward transmittance of the nonreciprocal single channel filter

Fig. 6. Schematic diagram of electric field distribution when odd mode light is incident forward and backward. (a) Forward incidence; (b) backward incidence

Fig. 7. Schematic diagram of nonreciprocal dual-channel filter

Fig. 8. Effect of the change of radius of dielectric column M on forward transmittance

Fig. 9. Effect of R_S on the forward transmittance of the filter

Fig. 10. Effect of R_N on the forward transmittance of the filter

Fig. 11. Effect of different coupling length on forward transmittance

Fig. 12. Electric field distribution at forward and backward incidence. (a) Normal incidence from port 1 (1574 nm); (b) normal incidence from port 1 (1534 nm); (c) backward incidence from port 2; (d) backward incidence from port 3