Tunable wideband microwave photonic phase shifter and true time delay using a waveguide bragg grating.

We present a tunable wideband microwave photonic (MWP) processor that simultaneously enables precise phase shifting and true-time delay (TTD) control. The core of this device is a compact phase-shifted waveguide Bragg grating (PS-WBG) integrated into a silicon photonic (SiPh) platform. The system uses a dual-drive Mach-Zehnder modulator (DD-MZM) to generate an optical single-sideband modulated signal from a continuous-wave laser source. The modulated signal is processed through a PS-WBG that provides optical bandpass filters with a nearly rectangular transmission spectrum and sharp phase shifts. Our design offers a dynamically adjustable phase shift of up to 600° with minimal RF power variation of 2 dB over a broad 33 GHz (12-45 GHz) bandwidth. Additionally, it provides a highly stable delay of up to 196 picoseconds (ps) across an 8.5 GHz instantaneous bandwidth. Theoretical analysis and simulation results confirm the tunability and wideband operation of the proposed MWP system.