Passive Synchronization of 1.06-and 1.53-μm 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 mu m, 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 largeenergy 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 mu J at 1.06 mu m and 1.20 mu J at 1.53 mu m, respectively, which is, to the best of our knowledge, the largest pulse energy obtained from graphene Q-switched all-fiber laser.