Dual-frequency Yb³⁺-doped DBR fiber laser with 32 GHz frequency difference

A dual-frequency Yb3+-doped distributed Bragg reflection (DBR) fiber laser was demonstrated, which used a home-made dual-wavelength low reflectivity FBG as the output port of the DBR fiber laser. The wavelength spacing of the FBG was about 0.12 nm, corresponding to 32 GHz frequency difference. The dual-wavelength of the laser output was 1 063.09 nm and 1 063.21 nm, respectively. The spectral signal noise ratio was more than 60 dB. Each of the wavelengths included only one longitudinal mode. The beat frequency of the dual-frequency was 32.014 GHz. The signal-noise ratio of the frequency spectrum was more than 35 dB. Benefitted from the compact structure and the strong anti-interference capability of the fiber laser, the dual-frequency fiber laser is promising as the candidate of high-quality microwave signal generator for the applications such as microwave sensing and communications.