Multi-wavelength Tm/Ho co-doped mode-locked fiber laser with a simple cavity

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.