Anisotropic materials are characterized by a unique optical response, which is highly polarization-dependent. Of particular interest layered formed the stacking of two-dimensional (2D) crystals that naturally anisotropic in direction perpendicular to 2D planes. Black phosphorus (BP) stack phosphorene and semiconductor with direct band gap. We show angular dependence polarized Raman spectra BP rather unusual can be explained only considering complex values for tensor elements. This result...

Abstract We demonstrated a method to construct high efficiency saturable absorbers based on the evanescent light field interaction of CVD monolayer graphene deposited side-polished D-shaped optical fiber. A set samples was fabricated with two different core-graphene distances (0 and 1 μm), covered ranging between 10 25 mm length. The mode-locking achieved best pulse duration 256 fs, shortest reported in literature EDFL. As result, we find criterion polarization relative extinction ratio...

We introduce a new low-loss semiconductor structure for femtosecond intracavity mode locking in low-gain solid-state lasers. This monolithic device can be engineered to exhibit specific saturation characteristics desirable Self-starting 90-fs pulses are obtained with Ti:sapphire and diode-pumped Cr:LiSAF discuss mode-locking mechanisms quantum-well passively mode-locked

Black phosphorus has recently emerged as a new layered crystal that, due to its peculiar and anisotropic crystalline electronic band structures, may have important applications in electronics, optoelectronics photonics. Despite the fact that edges of crystals host range singular properties whose characterization exploitation are utmost importance for device development, black remain poorly characterized. In this work, atomic structure behaviour phonons near different experimentally...

For the first time, we demonstrated fabrication of mechanically exfoliated molybdenum disulfide (MoS2) samples deposited onto a D-shaped optical fiber. The MoS2 flakes were stacked 1.2 µm PVA (polyvinyl alcohol) and 300 nm PMMA (polymethyl methacrylate) layers then transferred directly side polished surface fiber with polishing length 17 mm no distance from core. sample exhibited high polarization performance as polarizer relative extinction ratio 97.5%. By incorporating saturable absorber...

We study the very early processes of photogenerated carrier transport in GaAs and Si using THz nonlinear spectroscopy with 10 fs time resolution. This ultrahigh resolution allows us to clearly separate instantaneous creation polarized electron-hole pairs subsequent motion for first time. In addition, our results give clear demonstration distinct phases transport; ballistic transport, electron velocity overshoot, steady-state drift.

We demonstrate wavelength-division multiplexing with a single broadband femtosecond source by slicing the 3.7-THz spectral bandwidth of 85-fs laser pulses into 16 channels that are modulated individually.

We present high mode-locking performances from an erbium-doped fiber laser (EDFL) by using graphene oxide (GO) and reduced (r-GO) as saturable absorbers (SA) deposited onto the polished surface of a D-shaped optical fiber. The samples were prepared with different concentrations its characterization was performed microscope, Raman spectrometer, nonlinear absorption measurements, polarization setup, analysis. As 1550-nm polarizer, best GO exhibited higher extinction ratio (PER) 7.94 (7.65) dB,...

For the first time, we report a femtosecond mode-locked Erbium-doped fiber laser (EDFL) by using mechanically exfoliated graphite deposited onto D-shaped optical fiber. The flakes were stacked polyvinyl alcohol/polymethyl methacrylate thick layers, and then transferred directly to polished surface of characterization sample was performed microscope Raman spectroscopy. By measuring its polarization performance, relative extinction ratio about 5.30 dB (70%) obtained, which resulted in broadest...

We study the supercontinuum (SC) generation from a passively mode-locked erbium-doped fiber laser (ML-EDFL) using two different samples of monolayer graphene saturable absorber (SA) onto side-polished surface D-shaped fiber, characterized with 98% and 65% polarization dependent loss (PDL), respectively. By first PDL SA (setup-1), output pulse spectral profile 11.6 nm bandwidth was obtained ML-EDFL subsequently amplified an amplifier (EDFA) to pump 2-m highly nonlinear (HNLF) 5-m ZBLAN...

Using a polarisation-maintaining erbium-doped fibre near the zero dispersion wavelength and bulk InGaAsP saturable absorber, authors passively modelock laser to generate nearly transform-limited 320 fs pulses with 40pJ energy. The produces stable state of linear polarisation semiconductor, which acts both as slow fast self-starts laser.

Este volume 35 da Revista Oikos: Família e Sociedade em debate objetiva aquecer o crítico sobre a atualidade do capitalismo no cenário de mudanças avanços das forças produtivas, bem como as transformações curso Estado, na sociedade cultura contexto Quarta Revolução Industrial.As discussões que se apresentam aqui orbitam luta classes consciência classe financeirizado mediado por novas tecnologias; processo acumulação capitalista. Estudos teóricos importância fundamental para organização...

We present a study on the characterization and quality evaluation of all-fiber chemical vapor deposition (CVD) graphene saturable absorber samples for Erbium-doped fiber laser (EDFL) mode locking. Optical end faces covered by CVD were analyzed Raman spectroscopy, classification criteria related to bands properties adopted in order evaluate quality. The analysis revealed that all samples, core was 100% graphene, with 88% average monolayer coverage, 82% low defect coverage. Graphene used as...

This paper presents, for the first time, successful transfer of exfoliated monolayer graphene flake to optical fiber end face and alignment its core. By fabricating optimizing a polymeric poly(methyl methacrylate) (PMMA) polyvinyl alcohol (PVA) substrate, it is possible obtain contrast up 11% green light illumination, allowing identification flakes that were transferred samples aligned With Raman spectroscopy, demonstrated completely covers core, quality remains unaltered after transfer. The...

Herein we describe a successful protocol for graphite exfoliation using biphasic liquid system (water/dichloromethane, DCM) containing ionic liquids (ILs; 1,3-dibenzylimidazolium benzoate- and 1-naphthoate). The use of (surface active) IL sonication led to stable DCM/water (O/W) emulsion, which enhanced graphene formation, suppressed its re-aggregation decreased shear/cavitation damage. O/W emulsion stabilization by the ILs was studied dynamic light scattering (DLS), whereas their...

Surface properties are extremely important for materials applied in the biomedical areas such as poly(vinyl alcohol)—PVA. The precise control of surface characteristics on these may adjust and expand its applications. Here, we present a new strategy to tune alcohol)/graphene oxide (PVA/GO) films by manipulation GO particles (amount level oxidation) also situ reduction GO. Adopting different approach from methods currently proposed, process was carried out exposing PVA/GO hydrazine vapor...

The valley transport properties of a superlattice out-of-plane Gaussians deformations are calculated using Green's function and Machine Learning approach. Our results show that periodicity significantly improves the filter capabilities single Gaussian deformation, these manifest themselves in conductance as sequence by plateaus. We establish physical effect behind observed notch is coupling between counter-propagating transverse modes; complex relationship design parameters make difficult to...

Controlled growth of 2D gold nanostructures with tunable optical properties on the surface graphene oxide by a surfactant-free method.

In this work, an alternative technique to the traditional micromechanical exfoliation of two-dimensional materials is proposed, consisting isolated flakes graphite and molybdenum disulphide onto polymeric surfaces films. The set made up polymer fabricated by using a hot-press machine called stamp. stamp was used allocate also allow process take place just in one face flake. Optical microscopy, Raman spectroscopy photoluminescence results showed that multilayers, bilayers single layers...

Stacked chemical-vapour deposited (CVD) graphene monolayer samples were fabricated and applied as saturable absorbers in erbium-doped fiber laser (EDFL). Transient absorption experiments show that at the saturation regime, regardless number of stacked layers (from 1 to 5 layers), present ps recovery time. Pulses with duration from 0.60 1.17 generated an EDFL, depending on (i.e., linear optical absorption) used. The results it is possible increase a stacking without affecting its nonlinear...