Monolayer graphene coated Yb:YAG channel waveguides for Q-switched laser operation

We studied operation characteristics of an Yb:YAG channel waveguide laser, Q-switched by employing monolayer graphene. Uniform monolayer graphene grown by thermal chemical vapor deposition is transferred directly onto one end facet of the channel waveguide which simultaneously serves as an output coupling mirror (OC), making a monolithic Q-switched waveguide laser possible. In this cavity configuration, the Q-switched laser delivers a maximum average output power of 85 mW, corresponding to a pulse energy of 64 nJ at 1.33-MHz repetition rate. The laser performance of this device is compared with another cavity configuration, in which the monolayer graphene is coated onto separate OCs. In this case a shorter pulse duration of 79 ns is achieved, but the laser operation performance is worse with respect to efficiency and output power. The proposed monolithic approach demonstrates the potential for developing more compact Q-switched laser devices. (C) 2016 Optical Society of America