Wavelength-switchable dual-wavelength thulium-doped fiber laser utilizing photonic crystal fiber.

A dual-wavelength thulium-doped fiber laser with a wide switchable single-wavelength range is demonstrated by employing a polarization-maintaining photonic crystal fiber. A new type of comb filter is designed and its spectrum is simulated. A nonlinear polarization rotation module is inserted into the laser cavity to suppress intense gain competition. An output power instability as low as 0.84 dB has been attained. The switchable range of single-wavelength operation is 43.64 nm, and the slope efficiency is 1.79%, attained by optimizing the splicer parameter between the polarization-maintaining photonic crystal fiber and the single-mode fiber. There are five regions of dual-wavelength output from 1978.04 to 1986.51 nm, and the maximum and minimum wavelength intervals are 6.11 nm and 1.9 nm. • A novel structure and tunable filter using photonic crystal fiber can be utilized in Thulium-doped fiber laser. • The method of reducing welding loss between photonic crystal fiber and single mode fiber is presented. • Switchable single-wavelength emission can be achieved and the selection range is 43.64 nm. • There are five regions of dual-wavelength output from 1978.04 to 1986.51 nm. [ABSTRACT FROM AUTHOR]