A 2 μm all fiber multi-wavelength Tm/Ho co-doped fiber laser based on a simple ring cavity is experimentally demonstrated. Compared with other 2 μm multi-wavelength Tm/Ho co-doped fiber lasers, the multi-wavelength fiber laser is obtained by the gain saturation effect and inhomogeneous broadening effect without any frequency selector component, filter component or polarization-dependent component. When the pump power is about 304 mW, the fiber laser enters into single-wavelength working state around 1967.76 nm. Further increasing the pump power to 455 mW, a stable dual-wavelength laser is obtained at room temperature. The bimodal power difference between λ1 and λ2 is 5.528 dB. The fluctuations of wavelength and power are less than 0.03 nm and 0.264 dB in an hour, which demonstrates that the multi-wavelength fiber laser works at a stable state. Furthermore, a research about the relationship between the pump power and the output spectra has been made.
A multi-wavelength Tm/Ho co-doped mode-locked fiber laser achieved without any frequency selector, filter component, or polarization-dependent component is proposed in this paper. The fiber laser outputs 56 ps pulses at 7.09 MHz. As increasing the pump power from 26.12 to 29.50 dBm, the tuning range of the three wavelengths are 1918.641-1947.527 nm, 2179.852-2205.147 nm, and 2200.163-2226.420 nm, respectively. The fluctuations of wavelength and power are less than 0.400 nm and 0.512 dB within 45 minutes, which demonstrates a stable operation. Such a 3-wavlength fiber laser has the advantages of long wavelength, simple configuration, high stability, and low cost.