Investigation of All-Optical Tunable Notch Filter Based on Sum-Frequency Generation in a PPLN Waveguide

We propose and simulate an all-optical tunable notch filter based on a sum-frequency generation process in a periodically poled lithium niobate (PPLN) waveguide. The central wavelength of the filter can be tuned by adjusting the wavelength of input pump light. The maximum signal suppression at the central wavelength can be also changed by varying the power of input pump light. A maximum signal depletion of up to 34.4 dB is achieved when the central wavelength is tuned at 1545 nm. The simulation results show that this nonlinear optical filter owns a wide tuning range and steady 3-dB bandwidth on different signal power and wavelength values under low input pump power.