Distributed-feedback (DFB) fiber lasers can sustain the oscillation of two orthogonal polarizations at different frequencies, due to the fiber Bragg grating UV-induced birefringence . Such dual-frequency fiber lasers (DFFL) are promising as heterodyne sources but, in the context of microwave photonics, the stabilization of the beat frequency becomes necessary. Locking the beat frequency of a dual-frequency laser to a local oscillator by optical frequency-shifted feedback (FSF) has been proved to be efficient , and can be applied in principle to any dual-polarization laser. Here we investigate this FSF method to an Er3+- doped DFB fiber laser, resulting in an all-fibered 1.5μm system emitting a stabilized beat note at 1 GHz.
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