We report a study of an all-fiber Tm-doped fiber laser with tunable single wavelength emission and dual-wavelength generation operating in different laser wavelength ranges depending on the Tm-doped fiber (TDF) length. The wavelength selection and tuning for single wavelength laser operation and the adjustment of cavity losses for dual wavelength laser operation is obtained by temperature variations of the high birefringence fiber loop in a fiber optical loop mirror. Stable dual wavelength operation is achieved at the single wavelength tuning limits when cavity losses are balanced to generate two simultaneous laser lines with equal powers. A linear cavity fiber laser setup with TDF lengths of 2, 4, 8 and 12 m is used to obtain tunable single wavelength operation in a range of ~40 nm for each TDF length. A total tuning range of ~110 nm with the four different TDF lengths is achieved. At dual-wavelength laser operation the wavelength separation was ~48 nm. The maximal power efficiency of ~34.9% with a maximum output power of 274 mW was obtained with the use of TDF length of 4 m.

Abstract-A tunable dual-wavelength thulium doped fiber laser is demonstrated experimentally. For the first time for the 2-µm wavelength band we propose the independent tuning of the generated laser lines based on fiber Bragg gratings and the use of a Hi-Bi fiber optic loop mirror for the fine adjustment of the cavity losses to obtain stable dual-wavelength operation. Dualwavelength laser generation with the laser lines separation in the range from 0.3 to 6.5 nm is obtained. The laser emission exhibits an optical signal-to-noise ratio better than 56 dB. Improved stability with output power fluctuations less than 1 dB is observed in dual-wavelength generation with equal power of lines.

No abstract

Tunable dual-wavelength emission of a Tm-doped fiber laser based on two fiber Bragg gratings (FBGs) is experimentally demonstrated. By using two FBGs with central wavelengths at 2069.30 and 2069.44 nm, stable dual-wavelength laser generation in the 2 μm wavelength region is achieved by adjusting the differential loss of the two wavelengths in the laser cavity. Strain applied on the FBG allows independent tuning of the simultaneously generated wavelengths with separation between the laser lines in a range from 0.54 to 9 nm. The laser has output power fluctuations less than 0.093% for an output power of 77.3 mW.

We experimentally demonstrate dissipative soliton resonance effect in a 173-m long passively mode-locked figure-eight thulium doped fiber laser with a net anomalous dispersion. The duration of the wave-breaking-free pulse broadens with the increase of a pump power. At maximum pump power of 4.5 W, square pulses were generated with duration of 85.18 ns, average output power of 245 mW, pulse energy of 206 nJ, and repetition rate of 1.19 MHz.