C+L band multi-wavelength fiber laser based on cascaded semiconductor optical amplifier

In this paper, a multi-wavelength fiber laser based on cascaded semiconductor optical amplifier (SOA) was proposed by using a high birefringence fiber loop mirror (Hi-Bi FLM) as wavelength filter. The 0.6nm homogeneous broadening line-width of the SOA enabled laser oscillation with WDM ITU-grid spacing possible. With this configuration, SOAs with small signal gain peak wavelengths at 1540nm and 1510nnm were cascaded as gain medium in the laser for laser oscillating in C+L band. The output results with different driving current of SOAs were obtained and compared experimentally. The wavelength spacing of this laser was controlled by using different lengths of Hi-Bi fiber. By using 5.9m Hi-Bi fiber in Hi-Bi FLM, 100GHz wavelength spacing was obtained. The output 26 wavelengths within 6dB bandwidth spacing on 100GHz were obtained. These multi-wavelengths covered C+L band and were centered on 1566.599nm. The line-width of each channel was 0.102nm with more than 25dB SNR. All these channels can be continuously tuned over 50GHz by controlling the polarization controller in Hi-Bi FLM. Output of multi-wavelength fiber laser with only one SOA as gain medium was also presented for comparison.