Influence of Parameters in the Design of a Faceted Structure for Incoherent Beam Shaping

A reflective faceted structure is proposed to reshaping an incoherent light beam into two focalized spots-To obtain the desired irradiance distribution on a detector,custom optimization function is written,and the two dimensional tilt angles of each facet are optimized automatically in a pure non-sequential mode in Zemax OpticStudio 16.The result is also confirmed inside LightTools&2 from Synopsys.For measuring the quality of the optimization result in the case of two spots focalization,four factors including efficiency on the detector,uniformity,the root mean square error and the correlation coefficient are calculated.These four factors are used to evaluate the influence of several parameters on the irradiance distribution.These parameters include the incidence angle,the divergence angle,the facet size,the source type and the resolution of the facet angular positions.Finally,an analysis of those parameters is made and the performance of this type of component is demonstrated.

A Better Reconciliation of Hubble Tension in the Dark Energy Scalar Field

Hubble tension between the local measurement and global observation has been a key problem in cosmology.In this paper,we consider the quintessence scalar field,phantom field and quintom field as the dark energy to reconcile this problem.Different from most previous work,we start from the dimensionless equation of state(w)of dark energy,not a parameterization of potential.The combined analysis shows that observational data sets favor Hubble constant H0=71.3-0.917+0.854 km s^(-1)Mpc^(-1),which can reconcile Hubble tension within 1.20σ.We also perform a Bayes factor analysis using the MCEvidence code,and confirm that the phantom scalar field is still the most effective.To investigate the reason of Hubble tension,we analyze the density parameter.The comparison shows that the scalar fields provide a slightly largerΩbh2 and smallerΩch2 than the standardΛCDM model.We finally analyze a possible reason of Hubble tension from the kinematic acceleration?.We find an interesting physical phenomenon.The acceleration a in these scalar fields are similar as theΛCDM model at about redshift z>0.5.However,they increase and deviate from each other at low redshift,especially in the near future.Only the?in phantom scalar field will decrease in the future.

Controlling electron collision by counterrotating circular two-color laser fields

Electron collision as well as its controlling lies in the core of study on nonsequential double ionization(NSDI).A single collision occurred in a convergent time is important to disclose the essential features of the electron correlation.However,it is difficult to form such a collision.By using counterrotating circular two-color(CRTC)laser fields,we show that a single electron collision can be achieved in a convergent time and a net electron correlation is set up within the sub-femtosecond time scale in the NSDI process of Ar atoms.The proposed method is also valid for other atoms,provided that one chooses the frequency and intensity of the CRTC field according to a scaling law.

Few-layer Ti_(3)CN MXene for ultrafast photonics applications in visible band

Ti_(3)CN,as a typical hetero-MXene,has attracted tremendous attention for its unique properties.However,its ultrafast photonics applications are still rare.Here,the few-layer Ti_(3)CN MXene was successfully prepared by selective etching and molecular delamination technique.The nonlinear optical response of few-layer Ti_(3)CN MXene at 640 nm was studied using the open-aperture Z-scan technique.The asprepared Ti_(3)CN MXene sample exhibited excellent nonlinear saturable absorption characteristics,resulting in the nonlinear absorption coefficient b of
4.05×10^(-2)cm/GW,which was one order of magnitude larger than that of black phosphorus(BP)and molybdenum disulfide(MoS_(2)).For the optical modulation applications of few-layer Ti_(3)CN MXene,passively Q-switched(PQS)solid-state visible lasers based on Ti_(3)CN saturable absorber(SA)at 522 nm,607 nm,639 nm,and 721 nm were successfully realized.Furthermore,a Ti_(3)CN-based stable passively mode-locked Pr:YLF red laser was also successfully achieved with a pulse duration of 30 ps,and the corresponding repetition rate was 73.1 MHz.The optical modulation device based on few-layer Ti_(3)CN MXene shows good performance.Our work demonstrates that the tremendous prospects of the few-layer Ti_(3)CN MXene as a visible optical modulation device in ultrafast photonics applications.

A waterproof and breathable Cotton/rGO/CNT composite for constructing a layer-by-layer structured multifunctional flexible sensor

Developing a cotton fabric sensing layer with good waterproofness and breathability via a low-cost and eco-friendly method is increasingly important for the construction of comfortable and wearable electronic devices.Herein,a waterproof and breathable cotton fabric composite decorated by reduced graphene oxide(rGO)and carbon nanotube(CNT),Cotton/rGO/CNT,is reported by a facile solution infiltration method,and we adopt such Cotton/rGO/CNT composite to develop a layer-by-layer structured multifunctional flexible sensor,enabling the high-sensitivity detection of pressure and temperature stimulus.Particularly,the multifunctional flexible sensor exhibits a high response toward tiny pressure,demonstrating salient superiority in the continuous and reliable monitoring of human physiological information.Concerning temperature sensing,a good linear response for the temperatures ranging from 28 to 40℃ is achieved by the multifunctional flexible sensor and gives rise to be successfully applied to the non-contact real-time monitoring of human respiration signal.Finally,an array consisting of multifunctional flexible sensors further demonstrates its feasibility in perceiving and mapping the pressure and temperature information of contact objects.This work provides a feasible strategy for designing cotton-based sensing layers that can effectively resist liquid water penetration and allow water vapor transmission,and offers reasonable insight for constructing comfort and multifunctional wearable electronics.

Two-dimensional tellurium saturable absorber for ultrafast solid-state laser

Two-dimensional(2 D) Te nanosheets were successfully fabricated through the liquid-phase exfoliation(LPE) method. The nonlinear optical properties of 2 D Te nanosheets were studied by the open-aperture Z-scan technique. Furthermore, the continuous wave mode-locked Nd:YVO4 laser was successfully realized by using 2 D Te as a saturable absorber(SA) for the first time, to the best of our knowledge. Ultrashort pulses as short as 5.8 ps were obtained at 1064.3 nm with an output power of 851 m W. This primary investigation indicates that the 2 D Te SA is a promising photonic device in the fields of ultrafast solid-state lasers.

耦合无枝晶锌负极和可逆脱嵌钙离子的磷酸钒钠正极实现先进钙锌混合离子电池

混合离子电池综合了单一离子电池的优点,为开发高性能二次电池提供了新的见解.本文合成了一种有无定形活性碳和还原氧化石墨烯包覆的NASICON型正极材料(NVP@AC@rGO)用于钙离子的可逆脱嵌,并组装了一种与锌金属负极和水系混合电解质耦合的Ca/Zn离子混合电池.这种完美的结合不仅充分发挥了钙离子在NASICON结构中优异的扩散动力学,而且巧妙利用钙离子的低还原电位,形成静电屏蔽效应,从而抑制了锌枝晶的形成.因此,该混合电池具有超高的比容量,出色的倍率性能以及循环稳定性.这种巧妙的组合平衡了单一多价离子电池的优缺点,为设计高性能的水性多价离子电池提供了一种新的可行途径.

Ultrasensitive and stable all graphene field-effect transistor-based Hg^(2+)sensor constructed by using different covalently bonded RGO films assembled by different conjugate linking molecules

As"molecular bridge,"coupling agents can not only realize the covalent connection of composites,but also affect their properties,thus affecting the properties of devices based on them.Herein,leveraging differences in charge conduction properties of the(3-aminopropyl)trimethoxysilane and 5,10,15,20-tetrakis(4-aminophenyl)-21H,23H-porphine caused by conjugacy structural differences,two kinds of layerby-layer assembled smart carbon materials with different electrical properties are obtained at the same reduction temperature.The two graphene ultrathin films are then“planted”on Si/SiO2 substrates,respectively,as semiconductor layer and source/drain electrodes to fabricate an ultra-stable all-graphene field effect transistor(AG-FET).Enabled by the covalent functionalized configuration and the functionally diverse of coupling agents,the AG-FET obtained by this simple method won the high electrical characteristics,the hole,electron mobility,and the shelflife could reach 3.79 cm2/(V·s),3.78 cm2/(V·s),and 18months,respectively.In addition,good material stability and excellent device structure endow the device exceptional stability,electrical stability,and solvent resistance,improving its application prospect in solution phase sensing/detection.Such characteristics could be used to sense,transduce,and respond to external stimuli,especially in solution phase to monitor the important analytes,such as Hg^(2+)in a flowing sewage environment.We believe that such easy-to-manufacture AG-FETs with ultrahigh performance and ultrahigh stability could also show great application prospects in other significant fields.

Ultra-fast and linear polarization-sensitive photodetectors based on ReSe_(2)/MoS_(2) van der Waals heterostructures

Recently,van der Waals heterostructures(vdWHs)constructed by transition-metal dichalcogenides(TMDCs)have come under the research spotlight owing to their excellent capabilities,multiple functionalities,and innovative architecture for advanced optoelectronic devices.Herein,novel heterojunction photodetectors composed of monolayer molybdenum disulfide(MoS2)and few-layer rhenium selenide(ReSe_(2))are explored for ultra-fast and polarization detection.Owing to the enhanced light-matter interactions and type-II band alignment of the ReSe_(2)/MoS_(2) heterostructure,the photodetector exhibits impressive performances at 638 nm in terms of a high on/off ratio~104,large photoresponsivity~3.52 A/W,high specific detectivity~1011 Jones,and large 3 dB frequency of 65.7 kHz.In addition,ultrafast rise/decay times(5.0/9.1 ms)are obtained under pulsed incident light contributed to the built-in electric field at the heterointerface,demonstrating a result one or two orders of magnitude faster than the currently reported values of group VII-TMDCs based photodetectors.Beyond the conventional photodetection,this photodetector also displays polarization detection capability with sensitivity 1.35.Such Re-based vdWHs provide superior platforms for the realization of ultra-fast and polarization-sensitive photodetection in broadband spectrum.