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Register a new userMonolayer Graphene as Saturable Absorber in Mode-locked Laser
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We demonstrate that the intrinsic properties of monolayer graphene allow it to act as a more effective saturable absorber for mode-locking fiber lasers compared to multilayer graphene. The absorption of monolayer graphene can be saturated at lower excitation intensity compared to multilayer graphene, graphene with wrinkle-like defects, and functionalized graphene. Monolayer graphene has a remarkable large modulation depth of 95.3%, whereas the modulation depth of multilayer graphene is greatly reduced due to nonsaturable absorption and scattering loss. Picoseconds ultrafast laser pulse (1.23 ps) can be generated using monolayer graphene as saturable absorber. Due to the ultrafast relaxation time, larger modulation depth and lower scattering loss of monolayer graphene, it performs better than multilayer graphene in terms of pulse shaping ability, pulse stability and output energy.
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Graphene is at the center of a significant research effort. Near-ballistic transport at room temperature and high mobility make it a potential material for nanoelectronics. Its electronic and mechanical properties are also ideal for micro and nanomechanical systems, thin-film transistors and transparent and conductive composites and electrodes. Here we exploit the optoelectronic properties of graphene to realize an ultrafast laser. A graphene-polymer composite is fabricated using wet-chemistry techniques. Pauli blocking following intense illumination results in saturable absorption, independent of wavelength. This is used to passively mode-lock an Erbium-doped fibre laser working at 1559nm, with a 5.24nm spectral bandwidth and ~460fs pulse duration, paving the way to graphene-based photonics.
We study analytically the plasmonic modes in the graphene-coated dielectric nanowire, based on the explicit form of nonlinear surface conductivity of graphene. The propagation constants of different plasmonic modes can be tuned by the input power at the order of a few tenths of mW. The lower and upper mode bifurcation branches are connected at the limitation value of the input power. Moreover, due to the nonlinearity of graphene, the dispersion curves of plasmonic modes at different input powers form an energy band, which is in sharp contrast with the single dispersion curve in the limit of zero input power.
We report a 2mu m ultrafast solid-state Tm:Lu2O3 laser, mode-locked by single-layer graphene, generating transform-limited~410fs pulses, with a spectral width~11.1nm at 2067nm. The maximum average output power is 270mW, at a pulse repetition frequency of 110MHz. This is a convenient high-power transform-limited laser at 2mu m for various applications, such as laser surgery and material processing.
We study extreme events occurring in the transverse $(x,y)$ section of the field emitted by a broad-area semiconductor laser with a saturable absorber. The spatio-temporal events on which we perform the statistical analysis are identified as maxima of the field intensity in the 3D space $(x,y,t)$. We identify regions in the parameter space where extreme events are more likely to occur and we study the connection of those extreme events with the cavity solitons that are known to exist in the same system, both stationary and self-pulsing.
Black phosphorus, a newly emerged two-dimensional material, has attracted wide attention as novel photonic material. Here, multi-layer black phosphorus is successfully fabricated by liquid phase exfoliation method. By employing black phosphorus as saturable absorber, we demonstrate a passively Q-switched Er-doped ZBLAN fiber laser at the wavelength of 2.8 {mu}m. The modulation depth and saturation fluence of the black phosphorus saturable absorber are measured to be 15% and 9 {mu}J/cm2, respectively. The Q-switched fiber laser delivers a maximum average power of 485 mW with corresponding pulse energy of 7.7 {mu}J and pulse width of 1.18 {mu}s at repetition rate of 63 kHz. To the best of our knowledge, this is the first time to demonstrate that black phosphorus can realize Q-switching of 2.8-{mu}m fiber laser. Our research results show that black phosphorus is a promising saturable absorber for mid-infrared pulsed lasers.
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