Actively Mode-locked Fiber Laser with Graphene Fiber Modulator

An actively mode-locked (ML) fiber laser is demonstrated to produce a 198 picosecond (ps) short-pulse train, featuring voltage-control repetition rates. A cost-effective strategy for overcoming the weak light absorption in graphene is demonstrated by integrating graphene into etched single-mode fiber (SMF), with advantages of adequate light-graphene interaction and integration of fiber system. The active modulation is realized by a graphene fiber modulator (GFM) in the ring fiber cavity, which shows a transparency modulation of 3.4 dB. As a result, stable active fundamental and second-order harmonic mode locking are demonstrated, allowing the generation of stable pulse trains with repetition rates of 12.4 and 24.7 MHz around 1558.3 nm. Such fiber device based on graphene can be feasible seeds for optical fiber light source in many applications.