Graphene-like two dimensional materials, such as WS2 and MoS2, are highly anisotropic layered compounds that have attracted growing interest from basic research to practical applications. Similar with few-layer has remarkable physical properties. Here, we demonstrate for the first time nanosheets exhibit ultrafast nonlinear saturable absorption property high optical damage threshold. Soliton mode-locking operations achieved separately in an erbium-doped fiber laser using types of WS2-based...

Molybdenum disulfide (MoS 2 ) and tungsten (WS ), two representative transition metal dichalcogenide materials, have captured tremendous interest for their unique electronic, optical, chemical properties. Compared with MoS WS , molybdenum ditelluride (MoTe (WTe possess similar lattice structures while having smaller bandgaps (less than 1 eV), which is particularly interesting applications in the near‐infrared wavelength regime. Here, few‐layer MoTe /WTe nanosheets are fabricated by a liquid...

Transition-metal dichalcogenides, such as tungsten disulfide (WS2) and molybdenium (MoS2), are highly anisotropic layered materials have attracted growing interest from basic research to practical applications due their exotic physical property that may complement graphene other semiconductor materials. WS2 nanosheets found exhibit broadband nonlinear saturable absorption property, absorbers (SAs) fabricated by depositing on side-polished fibers. Attributing the weak evanescent field long...

Abstract Few-layer transition-metal dichalcogenide WSe 2 /MoSe nanosheets are fabricated by a liquid exfoliation technique using sodium deoxycholate bile salt as surfactant and their nonlinear optical properties investigated based on balanced twin-detector measurement scheme. It is demonstrated that both types of exhibit saturable absorption at the wavelength 1.55 μm. By depositing side polished fiber (SPF) or mixing with polyvinyl alcohol (PVA) solution, SPF-WSe absorber (SA), SPF-MoSe SA,...

Cylindrical vector beams and vortex beams, two types of typical singular optical characterized by axially symmetric polarization helical phase front, possess the unique focusing property ability carrying orbital angular momentum. We discuss formation mechanisms such in few-mode fibers under basis show recent advances generating techniques that are mainly based on long-period fiber gratings, mode-selective couplers, offset-spliced fibers, tapered fibers. The performances cylindrical generated...

Transition metal dichalcogenides, a family of two-dimensional material with unusual electronic, optical, mechanical, and electrochemical properties, have received much research attention in recent years. Here we demonstrate that, another type few-layer transition rhenium disulfide (ReS <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> ) nanosheets display saturable absorption property at 1.55 μm. By incorporating the ReS polyvinyl alcohol...

We propose a method to generate the high-order optical vortex in few-mode fiber via cascaded acoustically driven vector mode conversion. Theoretical analysis showed that conversion induced by grating (AIFG) could occur between two HE modes with adjacent azimuthal numbers. In experiment conducted at 532 nm, AIFGs were simultaneously same segment of radio frequency source containing different components. One AIFG was used convert left- and right-handed circular polarization fundamental...

We presented a method to actualize the optical vortex generation with wavelength tunability via an acoustically-induced fiber grating (AIFG) driven by radio frequency source. The circular polarization fundamental mode could be converted first-order through AIFG, and its topological charges were verified spiral pattern of coaxial interference between Gaussian-reference beam. A spectral tuning range from 1540 nm 1560 was demonstrated slope 4.65 nm/kHz. conversion efficiency 95% within whole range.

Theoretical analysis and experimental demonstration are presented for the generation of cylindrical vector beams (CVBs) via mode conversion in fiber from HE11 to TM01 TE01 modes, which have radial azimuthal polarizations, respectively. Intermodal coupling is caused by an acoustic flexural wave applied on fiber, whereas polarization control necessary conversion, i.e. HE11x→TM01 HE11y→TE01 vibration along x-axis. The frequency RF driving signal actuating determined phase matching condition...

Cylindrical-vector beams (CVBs) with axial symmetry in polarization and field intensity are gathering increasing attention from fundamental research to practical applications. However, a majority of the CVBs generated by modulating light free space, temporal durations far away ultrafast regime. Here, an all-fiber based CVB laser is demonstrated via intermodal coupling two mode fibers. In domain, chirp-free pulses formed combined actions saturable absorption, self-phase modulation, anomalous...

Abstract Sb 2 S 3 has great potential to become a good phase‐change material for visible and near‐infrared wavebands due its low loss high refractive index contrast, so interest lies in the technology development. This work investigates intermediate states their cycling durabilities by employing continuous‐wave laser crystallization femtosecond amorphization. By considering stratified partial amorphization non‐uniform intensity distribution along propagation film, double‐layer model is...

Recent studies on regional haze pollution over China come up in general with strong variability of main causes heavy polluted episodes, linkage local specificities, sources and characteristics. This paper therefore aims at elucidating the specific formation mechanisms observed episodes 1–15 November 2015 Northeast region considered as one biggest megacity clusters China. The mega-city cluster, including Heilong Jiang, Jilin Liaoning provinces, is adjacent to Russia north, Mongolian west,...

Mode coupling from the fundamental vector mode (HE11x) to cylindrical beams (CVBs) and optical vortex (OVBs) of a few-mode fiber excited by two acoustic flexural waves with orthogonal perturbations is achieved using composite transducer. The HE11x converted TM01 TE01 modes, which have radial azimuthal polarizations, lowest-order modes F11x F11y, respectively. Furthermore, can also be ± 1-order OVBs HE21even±iHE21odd through combined F11x±iF11y. This technique provides useful way generating...

We demonstrate that ferroferric-oxide (Fe3O4) nanoparticles exhibit nonlinear saturable absorption property at 1.55 μm, and fabricate two filmy absorbers by embedding the into a polyvinyl alcohol (PVA) film or polyimide (PI) separately. In Fe3O4-PVA (Fe3O4-PI) Q-switched fiber laser, pulse repetition rate increases from 8.5 kHz (5.5 kHz) to 28 kHz (49 kHz) duration decreases 23.5 μs (47 μs) 6 μs (3.5 μs) varying pump power 25 mW (23 mW) 150 mW (650 mW). Experiment results indicate PI-based...

The broadband polarization-insensitive saturable absorption of Fe₂O₃ nanoparticles has been demonstrated for generating Q-switched cylindrical vector beams.

We propose and experimentally demonstrate a method to significantly extend the sensitive window of tilted fiber-Bragg grating (TFBG) into low-refractive-index region with integration graphene coating. The coupling between cladding modes TFBG coating results in an obvious modification cladding-mode envelope, which provides regime relying on graphene's complex refractive index. Interacting graphene-coated various aqueous solutions, we observe strongly enhanced sensitivity 1-1.428, is about...

Plasmonic nanocavities enable extreme light–matter interaction by pushing light down to the nanoscale. The dipolar feature of bright modes allows coupling with external excitation from free space but results in a radiating background, whereas nonradiating dark plasmon can hardly be excited. Here, we report for first time on strong between and anapole hybrid metal–dielectric nanostructure. With aid vanishing dipole characteristics plasmons, exhibit minimum far-field scattering maximum...

We proposed a method for generation of femtosecond optical vortex pulse in two-mode fiber based on an acoustically induced grating (AIFG) driven by radio frequency source. Theoretical analysis and experimental results demonstrated that the left- right-handed circular polarization fundamental modes could be converted to linearly polarized ±1-order through AIFG with mode conversion efficiency ∼95%. The off-axial interference experiment angle-dependent intensity examination were performed...

Optical nonlinearity due to intraband transitions (which is important for the application of epsilon-near-zero in metasurfaces and active plasmonics) requires a model fully predict spectrum, design considerations. The extended Drude model, presented here, serves this purpose. It further elucidates origin be both band nonparabolicity temperature-dependent mobility. matches experiment well representative compound indium tin oxide, simplifies description spectrally resolved optical...

We demonstrate a mode converter with an insertion loss of 0.36 dB based on coupling tapered single-mode and two-mode fibers, realize all-fiber flexible cylindrical vector lasers at 1550 nm. Attributing to the continuous distribution tangential electric field taper boundaries, laser is switchable between radially azimuthally polarized states by adjusting input polarization. In temporal domain, operation controllable among continuous-wave, Q-switched, mode-locked statuses changing saturable...

Abstract Tip-based plasmonic nanofocusing, which delivers light into a nanoscale region and achieves localized electromagnetic (EM) field enhancement beyond the diffraction limit, is highly desired for light-matter interaction-based super-resolution imaging. Here, we present nanofocusing at apex of silver (Ag)-coated fiber tip with internal illumination radial vector mode (RVM) generated directly in an optical based on acoustically-induced grating (AIFG). As illustrated by theoretical...

The loading of noble-metal nanoparticles (NPs) is an effective approach for the enhancement H2 sensing performances, although there have been rare reports focused on effect facets in performance. catalytic and adsorption performance nanocrystals mainly determined by their exposed facets, while gas sensors strongly correlated to reaction between gases sensor materials. Hence, it very important study different facets-exposed nanoparticles. In this study, a set shape-controlled Pd NPs prepared...