Dual polarization DFB fiber lasers as optical phase-locked microwave sources in the 1-10 GHz range

Fully fibered microwave-optical sources at 1.5 μm are studied experimentally. It is shown that the beat note between two orthogonally polarized modes of a distributed-feedback fiber laser can be efficiently stabilized using an optical phaselocked loop that uses the pump-power induced-birefringence as actuator. Beat notes at 1 GHz and 10 GHz of Erbium doped fiber laser are successfully stabilized to a reference synthesizer, passing from the 3 kHz free-running linewidth to a stabilized sub-Hz linewidth, with a phase noise as low as -75 dBc/Hz at 100 Hz offset from the carrier. An ErbiumYtterbium co-doped fiber laser is also investigated and successfully stabilized. Such dual-frequency stabilized lasers could provide compact integrated components for RF and microwave photonics applications.