Research On Dynamic Characteristics Of Graphene Pulse Erbium-Doped Fiber Laser

Pulses erbium-doped fiber lasers have attracted significant attention because of their wide field applications, such as in optical communications, materials processing, metrology, fiber optical sensing. In order to realize the pulse output of the fiber lasers, Q-switched and mode-locked technologies are two kinds of effective methods. Grephene, as a new saturable absorber, has desirable optical characteristics, such as ultrafast recovery time, higher damage threshold, deeper modulation depth, wider tunable range and low cost. In this paper, we experimentally research the dynamic characteristic of graphene pulse erbium-doped fiber lasers. And the specific research contents and results are as follows:1. Based on the energy level structure and the spectrum absorption characters of Er3+, we elaborate the operating principles of Q-switched and mode-locking pulses erbium-doped fiber lasers.2. Multiple polarization dynamic patterns of vector solitons, including fundamental solitons, bunched solitons, loosely or tightly bound states and harmonic mode locking have been observed experimentally in an erbium-doped fiber ring laser with graphene as a saturable absorber. By carefully adjusting the pump power and the orientation of the intra-cavity polarization controller, either polarization rotation or polarization locked operation have all been achieved for the above vector solitons, and the signal to noise ratio of our laser is 51 d B. As far as we know, there have no reports about bound vector solitons and harmonic mode locking vector solitons with high repetition frequency based on graphene saturable absorber.3. We experimentally research an all fiber, wavelength tunable, Q-switched erbium-doped fiber laser based on graphene saturable absorber. The wavelengths of the Q-switched laser can be accurately tuned over a range of ~35 nm by inserting into the cavity an unbalanced Mach–Zehnder interferometer(UMZI) with a variable optical delay line(OVDL) in one arm, which acts as an optical beam filter into the cavity. The Q-switched pulse duration and the pulse energy have all been characterized. The maximum pulse energy of 36.9 n J was obtained.