Tunable Tm-doped fiber ring laser operating at 1.9 µm band using force-induced fiber grating as wavelength tuner.

We report wavelength-tunable operation of a Tm-doped silica fiber laser by using a force-induced long-period fiber grating (LPFG) formed in a fiber ring resonator. The laser output wavelength is tuned by moving the transmission passband that is generated between adjacent resonance wavelengths due to the force-induced LPFG. By changing the grating period around 900 µm, we control the laser output wavelength between 1845 and 1930 nm.