The authors report a medium-power widely tunable single wavelength fiber laser. The laser wavelength was tuned from
1530 nm to 1575 nm. The gain medium consisted of a double-clad erbium-ytterbium codoped fiber. An un-pumped
elliptical core erbium-doped fiber was used as a saturable absorber inside the cavity to reduce the laser linewidth and
mode hopping. The output power of the laser at each lasing wavelength was more than 100 mW. The linewidth of the
laser was 8 MHz, measured using a scanning Fabry-Perot spectrum analyzer of resolution 6.5 MHz. The laser was stable
at room temperature with an intensity fluctuation of less than 0.2 dB.