Tunable and Switchable Multi-Wavelength Ytterbium-Doped Fiber Laser Based on Nonlinear Polarization Rotation Effect

In this paper, a simple and effective tunable multi-wavelength ytterbium-doped fiber laser (MWYDFL) is proposed and demonstrated. A nonlinear polarization rotation (NPR) structure, including polarization controller (PC) and polarization-dependent isolator (PDI) is used as the wavelength selector and works to generate intensity-dependence transmission to suppress the mode competition and solves the problem of greater intensity of side modes. Thus the stable all-fiber ring cavity structure is realized. Through controlling and adjusting the polarization of the PC in the cavity, a multi-wavelength and tunable single wavelength laser with good performance is achieved under the room temperature. The laser outputs of the single-wavelength can be tuned about 12 nm with an interval of about 1 nm from 1074.42 nm to 1090.97 nm. The side-mode suppression ratios (SMSRs) and the linewidths of these lasing lines are all over 50 dB and less than 0.02 nm. Single-wavelength, dual-wavelength, triple-wavelength and quadruple-wavelength can be switched by appropriately adjusting the PC. The power fluctuations and wavelength shifts are less than 2 dB and 0.02 nm in an hour at room temperature.