Switchable dual-wavelength fiber laser based on a phase-shifted fiber Bragg grating combined with Mach-Zehnder interferometer and Sagnac loop

摘要： A switchable dual-wavelength erbium-doped fiber laser is proposed and demonstrated. It is based on the finer filter effect of phase-shifted fiber Bragg grating (PSFBG), combining with the compound interference filtering effect of Mach-Zehnder interferometer (MZI) and Sagnac loop. By adjusting the polarization controller (PC) and tuning the delay, the switchable single- and dual-wavelength fiber laser with tunable wavelength spacing can be obtained. As a result, the dual-wavelength spacing as small as 0.04 nm is achieved, the output wavelength is from 1555.580 nm to 1559.928 nm, and the side mode suppression ratio (SMSR) is larger than 40 dB. The maximum wavelength drift of single-wavelength is less than 0.033 nm, and the maximum fluctuation of dual-wavelength is less than 0.02 nm. The experimental results show that the proposed fiber laser has important applications, such as in high fineness dense wavelength division multiplexing (DWDM) systems and other similar fields.