Switchable single-polarization dual-wavelength TDFL using PM Fabry–Perot filter

• The fiber laser sources operating in the near 2 μm band.
• A switchable single-polarization, dual-wavelength TDFL using PM F–P filter.
• The OSNRs of the single-polarization operation can reach 60 dB.
• The PERs of the single-polarization operation are higher than 33 dB.
• The slope efficiency of the single-polarization operation are 6.26% and 8.79%.

A switchable single-polarization (SP), dual-wavelength thulium-doped fiber laser using polarization maintaining (PM) Fabry–Perot (F–P) filter is proposed. A combination of the PM F–P filter, a polarization controller (PC) and a polarizer is used to ensure the SP lasing operation. A stable dual-wavelength lasing operation is obtained at 1941.82 nm and 1942.21 nm. By adjusting the PCs, the proposed laser can achieve SP single-wavelength lasing operation; the polarization extinction ratios are higher than 33 dB. When the pump power is higher than 2.98 W, the optical signal-to-noise ratios of the SP single-wavelength operation can reach 60 dB, and the output power variations are less than 0.32 dB (X-polarization) and 0.30 dB (Y-polarization). The slope efficiencies of SP lasing operation are 6.26% (X-polarization) and 8.79% (Y-polarization), respectively.