Tunable thulium-doped all-fiber laser

We demonstrate a tunable thulium-doped fiber ring laser wherein a single fused coupler acts simultaneously as the wavelength-division multiplexing for pump radiation, a lasing wavelength selective element, and output mirror. Temperature tuning of up to 2 nm//spl deg/C over a range of 40 nm and polarization tuning of over 100 nm within the spectral range from 1810 to 1930 nm have been obtained.