Switchable dual-wavelength fiber laser mode-locked by carbon nanotubes

We have proposed a switchable mode-locked fiber laser by means of carbon nanotube saturable absorber and fiber Bragg gratings (FBGs). The single-wavelength mode-locking operation can be switched between 1549.5 and 1559.5 nm, respectively, which correspond to the central wavelengths of two FBGs. With the appropriate setting of polarization controller, the stable dual-wavelength operation can be achieved due to the high stability of saturable absorber based on carbon nanotubes. Our method provides a simple, stable, low-cost, dual-wavelength ultrafast-pulsed source.