Tm-doped fiber laser with multiwavelength output and switchable wavelength difference based on nonlinear polarization rotation effect

In this paper, we report on the characteristics of multiwavelength output and wavelength difference switching in a Tm-doped fiber laser based on the nonlinear polarization rotation effect. The multiwavelength output and wavelength difference switching were realized through joint action of nonuniform intensity-dependent loss caused by the nonlinear polarization rotation effect and the polarization controller intertwined with Tm-doped fiber. Under dual-wavelength state, one wavelength could be switched within wavelength intervals of 44.7, 58.0, 68.2, and 73.1 nm, and the position of the other wavelength nearly remained unchanged in the switching process. The fiber laser with switchable wavelength difference has a broad application prospect in laser space communication and optical fiber sensing.