Electrically Tunable Microwave Photonic Filter Using a Phase-Shifted Waveguide Bragg Grating on Thin-Film Lithium Niobate

We propose and experimentally demonstrate an electrically tunable microwave photonic filter (MPF) based on a phase-shifted waveguide Bragg grating (PS-WBG) on thin-film lithium niobate (TFLN). The proposed MPF is realized via phasemodulation to intensity-modulation (PM-IM) conversion, in which a PS-WBG fabricated on TFLN serves as the optical notch filter. By mapping the optical spectral response of the PS-WBG to the microwave domain, a bandpass MPF can be realized. Leveraging the strong electro-optic effect of the lithium niobate, the center frequency of the MPF can be widely tuned by controlling the electrical power applied to the metal electrodes. Experimental results demonstrate that the implemented MPF has a 3-dB passband of 1.992 GHz and a wide tuning range from 3 GHz to 17 GHz. These performance metrics demonstrate strong potential of the proposed MPF for deployment in advanced radar imaging and next-generation wireless communications systems.