Tunable Microwave Photonic Notch Filter Based on LNOI Polarization Beam Splitter and Waveguide Grating True Time Delay Line

A tunable microwave photonic notch filter (MPNF) based on lithium niobate on insulator (LNOI) polarization beam splitter (PBS) and waveguide grating true time delay line (TTDL) is proposed and demonstrated experimentally. Based on LNOI, the PBS is achieved by simple structure in a short length utilizing the high birefringence property of lithium niobate (LN), and the TTDL is consisted of waveguide grating and flexible electrodes covering the grating. Utilizing the electro-optic effect of LN, wide tuning range and high tuning accuracy of time delay can be achieved by simply controlling the charging position of the electrodes. With the PBS and TTDL, the MPNF has a simple construction with low power consumption.