Investigation of a multiwavelength thulium-doped fiber laser incorporating a two-mode fiber filter

•A multiwavelength thulium-doped fiber laser incorporating a two-mode fiber filter was proposed.•The stability of the fiber laser was realized using nonlinear polarization rotation.•The maximum wavelength shift and optical power fluctuation of the eleven-wavelength operation are 0.08 nm and 1.86 dB, respectively.•The effects of the different experimental parameters on the output performance were investigated.