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.

We demonstrate graphene-functionalized self-phase-locking of laser pulses for a dramatically elevated repetition rate by employing an intrinsic resonating structure in a fiber ring laser cavity, the modes thereby satisfying the phase-matching condition passively, through both the resonator and the laser cavity. Graphene is directly synthesized around a 1-mm-diameter Cu wire catalyst, avoiding the deleterious transfer process. The wire provides a form factor to the fiber ring resonator as a versatile winding hub, guaranteeing damage-minimized and recyclable contact of the synthesized graphene with a diameter-controlled optical microfiber. In-depth analysis of the graphene confirms the optical nonlinearity critically required for pulse formation. The laser–graphene interaction, the intermode phase-locking function of graphene, and the pulse formation with the resonator are systematically elucidated to explain the experimentally generated laser pulses at a repetition rate of 57.8 gigahertz (GHz). Additionally, tunability of the repetition rate up to 1.5 GHz by the photothermal effect of graphene is demonstrated.

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Photonic integrated circuits (PICs) are notable for their enhanced functionalities with material flexibilities to find applications in wearable high‐speed data management systems. Due to the miniaturized dimensions of PICs, the employment of a nanomaterial having significant optical nonlinearity is critical. Here, it is demonstrated that a polymer waveguide can be harmonized with nonlinear graphene to form ultrashort laser pulses. The graphene works as nonlinear saturable absorber on the polymer waveguide prepared with a perfluorinated acrylic resin. The evanescent field of a laser propagating through the waveguide interacts with graphene to induce intracavity intensity modulation for femtosecond‐scale pulse formation. The laser output is characterized quantitatively as the central wavelength, spectral width, repetition rate, extinction ratio, and pulse duration, which are 1553.32 nm, 10.21 nm, 4.18 MHz, 76.03 dB, and 874 fs, respectively. Stable operation is verified over 3 h.