6.5 GHz Q-switched mode-locked waveguide lasers based on two-dimensional materials as saturable absorbers.

Two-dimensional (2D) materials have generated great interest in the past few years opening up a new dimension in the development of optoelectronics and photonics. In this paper, we demonstrate 6.5 GHz fundamentally Q-switched mode-locked lasers with high performances in the femtosecond laser-written waveguide platform by applying graphene, MoS2 and Bi2Se3 as saturable absorbers (SAs). The minimum mode-locked pulse duration was measured to be as short as 26 ps in the case of Bi2Se3 SA. The maximum slope efficiency reached 53% in the case of MoS2 SA. This is the first demonstration of Q-switched mode-locked waveguide lasers based on MoS2 and Bi2Se3 in the waveguide platform. These high-performance Q-switched mode-locked waveguide lasers based on 2D materials pave the way for practical applications of compact ultrafast photonics.