Metal–insulator–metal waveguide-based band-pass filter with circular ring resonator containing Kerr nonlinear medium

Tunable band-pass filter based on metal–insulator–metal (MIM) plasmonic circular ring resonators filled with Kerr nonlinear material is designed and numerically investigated by finite-difference time-domain (FDTD) simulations. Indium tin oxide (ITO) thin film with χ(3)=2×10−10 esu is chosen to fill in the circular ring resonator. The designed filter has one stopband within the spectra range of 800 nm to 1100 nm and the bandwidth of a resonance is 32 nm. It is found that the transmitted-peak can be tuned by changing the intensity of incident light. Due to the Kerr nonlinear effect, the resonant wavelength of the cavity exhibits a red-shift with the increasing of the incident intensity. Narrow band filtering function at desired wavelength can be realized through tuning of peak resonance wavelength by changing the intensities of incident light. The designed plasmonic filter can find important potential applications in highly integrated optical circuits.