Photonic generation of broadband RF phase shift with unbounded phase trajectory
A means of applying an adjustable RF phase shift over a broad band of frequencies is a requirement of diverse application. Photonic solutions to the generation of RF phase shifts have receive significant attention for reasons of reduced cost, compactness and simplicity, yet the achievement of a phase shift extending beyond 360˚ range remains a challenge. The circuit architecture of a compact and broadband RF phase shifter with unbounded range based on two parallel DP-MZM architecture is presented and verified by simulation verification and emulated using off the shelf low frequency electronic components. Results demonstrate that the complex transmission of the phase shifter follows a trajectory that may encircle the origin an arbitrary number of times in either direction. The proposed architecture can be implemented using commercially available DP-QPSK modulator or can be integrated in any material platform that offers linear electro-optic phase modulators.