Dual-wavelength mode-locked thulium-doped fiber laser based on carbon nanotube

In this paper, we demonstrate a dual-wavelength mode-locked thulium-doped fiber laser. The single-wall carbon nanotube is used as the mode-locker due to its large and ultrafast nonlinear optical responses. By tuning the pump power and adjusting the PC properly, stable dual-wavelength output can be achieved. The center wavelength of the dual-wavelength pulses are 1894 nm and 1907 nm, respectively. The repetition rate is about 17.64 MHz which exactly corresponds to the total length of the ring cavity. The signal-to-noise ratio is over 30 dB. It is a reliable method to realize dual-wavelength mode-locking operating at the range of 2 µm.