Tunable Low-Noise Photonic Microwave Synthesizer Based on a Polarization Multiplexing Fiber Brillouin Cavity

Microwave photonics has offered large bandwidth, high spectral purity and reconfigurability to applications such as radar and wireless communications[I,2], yet hardly delivers these merits simultaneously for frequency synthesis due to the challenge in manipulating broadband optical signals with high precision[3]. In this paper, an electro-optic architecture is proposed and principally demonstrated where the rapid tunability of the microwave source is inherited and its bandwidth is expanded through sidebands heterodyning. Furthermore, the process of stimulated Brillouin scattering (SBS) enabled by a polarization-multiplexed fiber cavity provides spectral purification, leading to significantly reduced phase noise and removal of undesired spurs.