Self-frequency-locked multi-wavelength erbium-doped fiber ring laser

A self-frequency-locked laser around 1.55 /spl mu/m is demonstrated by adding a segment of samarium-doped fiber (SDF) in an erbium-doped fiber (EDF) ring laser cavity. The narrow band output signal, with 3-dB linewidth of less than 0.15 nm and sidemode suppression ratio of 30 dB, is nearly polarization independent. A wavelength adjustable source within the 1.55 /spl mu/m band can be made by connecting various lengths of SDFs in each port of a 1/spl times/N synchronous optical switch simultaneously.