Dual-wavelength mode-locked fiber laser based on graphene materials

We demonstrate a dual-wavelength passive mode-locked Er-doped fiber laser using graphene as saturable absorber in a wavelength of 1.5 μ m. Using light precipitation method, graphene nanosheets were precipitated on the head face of fiber patch cord. This graphene saturable absorber has the advantages of flexibility, all-fiber configuration, and high optical damage threshold. Based on the saturable absorption of this graphene-based component and the cavity birefringent filtering characteristics, the stable dual-wavelength mode locking is obtained by properly adjusting the polarization controller of the laser ring cavity. The two center wavelengths of Er-doped fiber laser are 1557.78 nm and 1558.19 nm, respectively, and the repetition rate is 1.65 MHz at the second harmonic frequency, and the intracavity pulse energy can reach 24.2 nJ. In the simulation, the output pulse of full width at half maximum (FWHM) close to the experimental results and the result that one pulse disappears in the mode competition due to the limited gain are obtained, which can provide reference for further improvement of the performance of the laser.