Graphene Capacitor-Based Electrical Switching of Mode-Locking in All-Fiberized Femtosecond Lasers

Abstract

Effective high-capacity data management necessitates the use of ultrafast fiber lasers with mode-locking-based femtosecond pulse generation. We suggest a simple but highly efficient structure of a graphene saturable absorber in the form of a graphene/poly­(methyl methacrylate) (PMMA)/graphene capacitor and demonstrate the generation of ultrashort pulses by passive mode-locking in a fiber ring laser cavity, with simultaneous electrical switching (on/off) of the mode-locking operation. The voltage applied to the capacitor shifts the Fermi level of the graphene layers, thereby controlling their nonlinear light absorption, which is directly correlated with mode-locking. The flexible PMMA layer used for graphene transfer also acts as a dielectric layer to realize a very simple but effective capacitor structure. By employing the graphene capacitor on the polished surface of a D-shaped fiber, we demonstrate the switching of the mode-locking operation reversibly from the femtosecond pulse regime to a continuous wave regime of the ring laser with an extinction ratio of 70.4 dB.

Ultrafast Fiber Lasers with Low-Dimensional Saturable Absorbers: Status and Prospects

“…Therefore, it is obvious that exploring novel 2D materials as SA is continuous since it was first implemented. In addition, the controllability of key features in current 2D SAs and engineering in the laser cavity with tunable behavior of SAs also offers more functionalities in the development of controllable ultrafast fiber lasers [ 25 , 26 , 27 , 66 , 68 , 101 ]. Combining two or more similar or different 2D materials and building van der Waals heterostructures prospects towards developing multi-functional, high efficiency, broadband controllable photonic devices [ 102 , 103 ].…”

“…To date, there are very few investigations reported on the active control of fiber laser using the LD SA, such as graphene and CNT [ 25 , 26 , 27 , 66 , 67 , 68 ]. These can be done both optically and/or electrically.…”

“…Since the CNT and graphene were firstly suggested in 2004 and 2009 as an optical SA for mode-locked ultrafast fiber lasers, respectively [ 21 , 22 ], many other LD materials other than graphene, comprising TMDs, TIs, black phosphorus, bismuthine, MXenes, and metal-organic frameworks, quantum dots have been consecutively investigated, implying the significant growth of new SAs based on LD for ultrafast fiber lasers [ 8 , 35 , 58 , 65 ]. In addition to these, externally tunable in-line nonlinear LD SAs, where the fiber laser operation can be tuned from continuous wave, through Q-switched to passively mode-locked regime employing electrical gating or external optical bias, have also been demonstrated using various LD SAs [ 25 , 26 , 27 , 66 , 67 , 68 ].…”

Ultrafast Photonics of Ternary RexNb(1–x)S2 in Fiber Lasers

“…The high third-order optical nonlinearity, simplified fabrication process, wide absorption band, and ultrafast recovery time of these 2D materials endow them with unique superior capabilities for SA applications. Currently, various nanomaterials with excellent nonlinear optical characteristics, including graphene, transition metal chalcogenides (TMCs), metal organic frameworks, halide perovskites, MXene, bismuthene, black phosphorus, and tellurium, have been extensively used as SAs. − These 2D SAs are characterized by strong advantages as well as shortcomings. For example, the weak modulation effect and non-adjustable bandgap structure greatly limit the applications of graphene .…”

Directly Synthesized Graphene-Based Photonics and Optoelectronics Devices

“…Nevertheless, graphene is an ideal photonic and optoelectronic material due to the broadband optical properties [8][9][10][11][12][13][14]. The aforementioned characteristics forge the path for graphene to be a potential material for optoelectronic and photonic applications [15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30].…”