Stable, uniform, approximately linearly polarized dual-wavelength PM-EDF laser with tunable wide wavelength spacing using a compound filter

A stable uniformity approximately linearly polarized dual-wavelength polarization-maintaining erbium-doped fiber (PM-EDF) laser obtained by using a compound filter is proposed and experimentally demonstrated. By adjusting the polarization controllers (PCs), the output laser can not only be switched between single-wavelength and dual-wavelength operation, but is also tunable. Dual-wavelength lasing has the performance characteristics of uniformity, tunable wavelength spacing, tunable wavelength position, and the same approximately linear polarization. Besides, the peak power fluctuation and wavelength shift are monitored to be less than 0.2?dB and 0.02?nm during an hour, respectively. The characteristics of the two compound filters measured in the experiment are in accord with those of a theoretical analysis.