Reconfigurable and widely tunable microwave photonic filter with bandstop and bandpass modes using a phase-shifted waveguide Bragg grating

Integrated microwave photonic filters (MPFs) have attracted considerable interest for next-generation radio-frequency systems due to their compactness and reconfigurability. This work presents an ultra-wideband tunable MPF with switchable bandstop and bandpass responses. The proposed filter is based on a phase-shifted waveguide Bragg grating (PS-WBG) and a dual-drive Mach-Zehnder modulator (DD-MZM). The PS-WBG exhibits a broadband reflection spectrum with a narrow spectral notch at its center. The DD-MZM generates either a phase-modulated or quasi-single-sideband optical signal by adjusting the bias voltage, which dynamically controls the power ratio and phase difference between the optical sidebands. Propagating these signals through the PS-WBG enables reconfiguration between the two filtering states. Moreover, the central frequency of the MPF can be tuned simply by varying the optical carrier wavelength.