Multi-Wavelength Thulium-Doped Fiber Laser Using a Fiber-Based Lyot Filter

A multi-wavelength thulium-doped fiber laser using a fiber-based Lyot filter is proposed in 2-μm band for the first time. In the laser cavity, the fiber-based Lyot filter is used as the comblike wavelength selection component. By adjusting two polarization controllers, a stable multi-wavelength operation is obtained at room temperature, 17 output channels within 10-dB bandwidth from 1982 to 1998 nm are achieved. The flattened spectrum of multi-wavelength operation can obtained by using the 10% output coupling ratio. The different wavelength spacing of the fiber laser can be controlled by adjusting the polarization maintaining fiber lengths of the Lyot filters.