2.1μm tunable multi-wavelength holmium fiber laser

In order to generate the multi-wavelength fiber at 2.1 μm band, a tunable multi wavelength Ho³⁺-doped ring fiber laser based on all-fiber Sagnac interferometer was designed. A 3m long Ho³⁺-doped silica fiber was pumped by a Tm³⁺-doped fiber laser,and then the spontaneous radiation at 2.1 μm band was amplified.In the annular cavity,the Sagnac fiber interferometer consisted of an 8 m long polarization maintain fiber (PMF) and a polarization controller (PC),and the output wavelength at 2.1 μm waveband can be period tuned by the Sagnac interferometer.In experiment,a multi-wavelength laser at 2.1 μm waveband can be got,the output power can be tuned from 1 mW to 15 mW,and up to 6 wavelengths of laser output can be observed.By adjusting the PC in annular cavity ,the output tunable wavelength number can be realized from 1 to 6 at 2.1 μm band.