A tunable multi-wavelength fiber laser based on polarization maintaining microfiber

A novel tunable multi-wavelength erbium-doped fiber laser based on polarization-maintaining microfiber is proposed and experimentally demonstrated at room temperature. The 2.5-μm-diameter panda-type polarization-maintaining microfiber is combined with a polarization dependent isolator to select the mode and introduce polarization-dependent losses. At room temperature, when the pump power is 25 mW, not only the number of lasing wavelengths is switched from 1 to 4, but also a large range of wavelength tuning up to 41.7 nm is achieved. The 3 dB linewidths of laser output spectra are less than 0.05 nm and the optical signal-to-noise ratio is greater than 40 dB, up to 54 dB. When the fiber laser operates at a single-wavelength of 1561.66 nm, the wavelength shift and peak power fluctuation are within 0.02 nm and 0.4 dB in one hour.