Two-dimensional (2D) layered transition metal dichalcogenides (TMDs) have attracted significant interest in various optoelectronic applications due to their excellent nonlinear optical properties. One of the most important applications of TMDs is to be employed as an extraordinary optical modulation material (e.g., the saturable absorber (SA)) in ultrafast photonics. The main challenge arises while embedding TMDs into fiber laser systems to generate ultrafast pulse trains and thus constraints their practical applications. Herein, few-layered WS with a large-area was directly transferred on the facet of the pigtail and acted as a SA for erbium-doped fiber laser (EDFL) systems. In our study, WS SA exhibited remarkable nonlinear optical properties (e.g., modulation depth of 15.1% and saturable intensity of 157.6 MW cm) and was used for ultrafast pulse generation. The soliton pulses with remarkable performances (e.g., ultrashort pulse duration of 1.49 ps, high stability of 71.8 dB, and large pulse average output power of 62.5 mW) could be obtained in a telecommunication band. To the best of our knowledge, the average output power of the mode-locked pulse trains is the highest by employing TMD materials in fiber laser systems. These results indicate that atomically large-area WS could be used as excellent optical modulation materials in ultrafast photonics.

Ultrafast fiber lasers with broad bandwidth and short pulse duration have a variety of applications, such as ultrafast time-resolved spectroscopy and supercontinuum generation. We report a simple and compact all-fiber thulium-doped femtosecond laser mode-locked by carbon nanotubes. The oscillator operates in slightly normal cavity dispersion at 0.055 ps2, and delivers 152 fs pulses with 52.8 nm bandwidth and 0.19 nJ pulse energy. This is the shortest pulse duration and the widest spectral width demonstrated from Tm-doped all-fiber lasers based on 1 or 2 dimensional nanomaterials, underscoring their growing potential as versatile saturable absorber materials.

In this Letter, high-quality WS film and MoS film were vertically stacked on the tip of a single-mode fiber in turns to form heterostructure (WS-MoS-WS)-based saturable absorbers with all-fiber integrated features. Their nonlinear saturable absorption properties were remarkable, such as a large modulation depth (∼16.99%) and a small saturable intensity (6.23  MW·cm). Stable pulses at 1.55 μm with duration as short as 296 fs and average power as high as 25 mW were obtained in an erbium-doped fiber laser system. The results demonstrate that the proposed heterostructures own remarkable nonlinear optical properties and offer a platform for adjusting nonlinear optical properties by stacking different transition-metal dichalcogenides or modifying the thickness of each layer, paving the way for engineering functional ultrafast photonics devices with desirable properties.

Dengue fever (DF) is a vector-borne disease and a tremendous socioeconomic burden on tropical and subtropical countries worldwide. To explore the characteristics of DF epidemic in the Fujian province, information of DF cases in Fujian during 2004-2014 was collected and analyzed. The complete E genes of 48 viral isolates were amplified and sequenced for phylogenetic analysis. A total of 733 cases was reported, of which 612 (83.5%) occurred during the peak period from August to October. Additionally, 76% (190/250) of imported cases originated from Southeast Asia countries, by the epidemiological investigation. Phylogenetic analysis of the 48 viral isolates revealed that three genotypes (I, IV, V) of DENV1, and one genotype each of DENV2 (cosmopolitan) and DENV3 (I) circulated in Fujian during [2004][2005][2006][2007][2008][2009][2010][2011][2012][2013][2014]. Similar to the results of the epidemiological investigations, the source of most of the viral isolates, including imported and indigenous cases, may be Southeast Asia countries; however, importation from adjacent provinces was also observed in recent years. Overall, DF is considered an imported epidemic disease in Fujian. Increasing diversity of the viral source and geographic expansion of the area affected by DF in recent years highlights the necessity for strengthening surveillance of the DF epidemic and developing strategies for DF prevention and control in Fujian.dengue virus, E gene, phylogenetic tree, epidemiology, etiology Citation:

We demonstrate the fabrication of graphene-deposited tapered fibers (GDTFs), which can be used as saturable absorbers (SAs) for pulsed lasers. The advantages of GDTF SAs include flexibility, all-fiber configuration, and high optical damage threshold. The fabrication process is based on the interaction of the evanescent field of a tapered fiber with graphene. By in situ monitoring the transmitted power, the deposition process can be controlled, and the GDTF with a desirable level of nonsaturable absorption loss can be fabricated. We also study the dynamic deposition process by employing different waist diameters of tapered fibers and the different deposition powers. The results show that the deposition time can be significantly shortened with stronger evanescent field by decreasing the taper diameter or increasing the deposition power. Furthermore, by exploiting the GDTF as an intracavity passive power modulating element, we demonstrate efficient Q-switched and mode-locked erbium-doped fiber lasers, respectively.National Natural Science Foundation of China [61107038, 61177044]; Natural Science Foundation of Fujian Province of China [2011J01370]; Fundamental Research Funds for the Central Universities of China [2010121059]; Science and Technology on Electronic Information Control Laborator

We propose and demonstrate multiwavelength dissipative soliton (DS) generation in an all-normal-dispersion ytterbium-doped fiber laser based on a graphene-deposited tapered fiber (GDTF) device. Due to the interaction of the graphene with the evanescent field on the taper, the GDTF device possesses the characteristics of both saturable absorption and polarizing effect. Therefore, this device not only initiates the mode-locking operation based on the saturable absorption, but also induces both the special spectral filtering and nonlinear polarization evolution for shaping pulses into DSs. Simultaneous triple-wavelength DS operation around 1035 nm is thus achieved with a pulse energy of 6.4 nJ and pulse duration of 74.6 ps. Moreover, the DS operation is very stable with an RF signal-to-noise ratio of 62.5 dB.National Natural Science Foundation of China [61107038, 61177044

We demonstrate an integrated all-fiber mid-infrared (mid-IR) supercontinuum (SC) source generated by a 1.95 μm master oscillator power amplifier system and a single-mode ZBLAN (ZrF 4 -BaF 2 -LaF 3 -AlF 3 -NaF) fiber. The maximum average output power is 10.67 W with spectral bandwidth covering from ∼1.9 to 4.1 μm. The single-mode ZBLAN fiber and silica fiber are thermal-spliced to enhance the robustness and practicability of the system. It is, to the best of our knowledge, the first high-power integrated compacted all-fiber mid-IR SC source based on thermal-spliced silica fiber and ZBLAN fiber. ©

We numerically and experimentally analyze the output characteristics and pulse dynamics of carbon nanotube mode-locked fiber lasers near zero cavity dispersion (from 0.02 to ~-0.02 ps(2)). We focus on such near zero dispersion cavities to reveal the dispersion related transition between different mode-locking regimes (such as soliton-like, stretched-pulse and self-similar regimes). Using our proposed model, we develop a nanotube-mode-locked fiber laser setup generating ~97 fs pulse which operates in the stretched-pulse regime. The corresponding experimental results and pulse dynamics are in good agreement with the numerical results. Also, the experimental results from soliton-like and self-similar regimes exhibit the same trends with simulations. Our study will aid design of different mode-locking regimes based on other new saturable absorber materials to achieve ultra-short pulse duration.