Passive Synchronization of 1.06- and 1.53- m Fiber Lasers Q-switched by a Common Graphene SA

We demonstrate the passive synchronization of two large-energy Q-switched all-fiber lasers, operating at 1.06 and 1.53 μm, by sharing a common monolayer graphene Q-switcher. The fiber-compatible Q-switcher is constructed by transferring a monolayer CVD graphene nanosheet onto a fiber ferrule. By exploiting the broadband saturable absorption of graphene and optimizing the cavity designs, both the large-energy Q-switched Yb and Er/Yb double-clad fiber lasers are successfully synchronized. The Q-switching synchronization can be realized in the broad repetition-rate range of 9-20 kHz by adjusting the pump powers of the two lasers. The maximum pulse energies are 5.30 μJ at 1.06 μm and 1.20 μJ at 1.53 μm, respectively, which is, to the best of our knowledge, the largest pulse energy obtained from graphene Q-switched all-fiber laser.