Graphene mode-lockers for fiber lasers functioned with evanescent field interaction

Abstract

Employing graphene as an intracavity passive power modulating element, we demonstrate the efficient laser pulsation in high pulse-energy regime with evanescent field interaction between the propagating light and graphene layer. Graphene is prepared by the solution based reduction of graphene oxide, and dispersed homogeneously into the water for spray onto an all-fiber substrate, side-polished fiber. With the intracavity power up to 21.41 dBm, we ensure the robust high-energy operation without any thermal damage of graphene. Resultant output pulses have center wavelength, spectral width, and repetition rate of 1561.6 nm, 1.96 nm, and 6.99 MHz, respectively.

Monolayer graphene as a saturable absorber in a mode-locked laser

“…Previously, we have demonstrated the application of few-layer graphene [7][8][9] as well as graphene-polymer composites [10,11] as saturable absorbers in mode-locked lasers. Subsequently, another two groups also confirmed the mode-locking of lasers using chemically processed graphene film [12] and graphene-polymer composites [13] as saturable absorbers. In all these experiments, the saturable absorbers were multilayer graphene films or graphene composites and the unambiguous demonstration of saturable absorption from a single atomic layer of graphene film has yet to be achieved.…”

A stable, wideband tunable, near transform-limited, graphene-mode-locked, ultrafast laser

“…The water is then slowly evaporated in a desiccator at room temperature, resulting in a ~50 µm thick graphene-PVA (GPVA) composite [32,38]. Compared to other fabrication strategies for graphene saturable absorbers [39][40][41][42][43][44][45][46], our approach is easily scalable, and allows integration into various photonic systems [32,38,46]. Power-dependent absorption at six wavelengths is measured using an all-fiber based setup described in Ref.…”

“…After the first demonstration of a graphene-based mode-locker [32], a variety of lasers were reported exploiting graphene saturable absorbers for ultrafast pulse generation at 1 and 1.5 µm [38][39][40][41][42][43][44][45][46]. Reference [38] explained the fundamentals of the photo-excited carrier dynamics, which leads to Pauli-blocking and thus, saturable absorption, with good agreement between theory and experiment.…”

Optical Third-Harmonic Generation in Graphene

“…Because ideal freestanding monolayer graphene is centrosymmetric, its second-order nonlinear response vanishes within the dipole approximation [24]. In contrast, symmetry-allowed third-order nonlinear optical effects in graphene are remarkably strong, leading to studies that include saturable absorption [27][28][29][30][31][32], optical limiting [33,34], two-photon absorption [35], four-wave mixing (FWM) [36,37], and current-induced SHG [38]. In one notable FWM investigation, the authors have estimated the third-order nonlinear susceptibility of single-layer and multilayer graphene and demonstrated the capability of FWM for imaging of graphene using two input beams [36].…”