Tunable microwave generation based on a phase-shifted chirped fiber Bragg grating

We proposed a dual-wavelength single-longitudinal-mode (SLM) erbium-doped fiber (EDF) ring laser, incorporating a phase-shifted chirped fiber Bragg grating (PS-CFBG) in the laser cavity. The PS-CFBG consists of a permanent phase shift and a thermo-induced temporary phase shift to form two passbands in the spectrum. The wavelength spacing of the two passbands can be continuously tuned by scanning the thermal head along the grating. By heterodyning the dual lasing lines at a photodetector, a microwave signal with a tunable frequency was successfully obtained. The proposed fiber laser has potential applications in broadband wireless access network and optical sensing network.