Rod-airfoil interaction noise becomes a major issue in some aeronautical applications.The design of four wavy leading edges(WLEs)with varying wavelengths,bioinspired by the tubercles on humpback whales’flippers,aims ...Rod-airfoil interaction noise becomes a major issue in some aeronautical applications.The design of four wavy leading edges(WLEs)with varying wavelengths,bioinspired by the tubercles on humpback whales’flippers,aims to mitigate far-field noise.Among these cases,a reduction in the wavelength is found to be advantageous for noise suppression,with the smallest wavelength case achieving a maximum noise reduction of 1.9 dB.Furthermore,the noise radiation induced by WLEs is suppressed mainly at medium frequencies.The theory of multiprocess aeroacoustics is applied to reveal their underlying mechanisms.The dominant factor is the source cutoff effect,which significantly decreases the source strength on hills.Additionally,spanwise decoherence with phase interference serves as another crucial mechanism,particularly for reducing mid-frequency noise.展开更多
Multi-band optical networks are a potential technology for increasing network capacity.However,the strong interference and non-uniformity between wavelengths in multi-band optical networks have become a bottleneck res...Multi-band optical networks are a potential technology for increasing network capacity.However,the strong interference and non-uniformity between wavelengths in multi-band optical networks have become a bottleneck restricting the transmission capacity of multi-band optical networks.To overcome these challenges,it is particularly important to implement optical power optimization targeting wavelength differences.Therefore,based on the generalized Gaussian noise model,we first formulate an optimization model for the problems of routing,modulation format,wavelength,and power allocation in C+L+S multi-band optical networks.Our objective function is to maximize the average link capacity of the network while ensuring that the Optical Signal-to-Noise(OSNR)threshold of the service request is not exceeded.Next,we propose a NonLinear Interferenceaware(NLI-aware)routing,modulation format,wavelength,and power allocation algorithm.Finally,we conduct simulations under different test conditions.The simulation results indicate that our algorithm can effectively reduce the blocking probability by 23.5%and improve the average link capacity by 3.78%in C+L+S multi-band optical networks.展开更多
The purpose of this study is to analyze the impact of upper ocean dynamics on velocity bunching,represented by az-imuthal cutoff wavelength(i.e.,sea surface wind,wave,and current).In this study,over 1400 dual-polarize...The purpose of this study is to analyze the impact of upper ocean dynamics on velocity bunching,represented by az-imuthal cutoff wavelength(i.e.,sea surface wind,wave,and current).In this study,over 1400 dual-polarized(vertical-vertical(VV)and vertical-horizontal(VH))Sentinel-1(S-1)synthetic aperture radar(SAR)images collected in tropical cyclones(TC)are utilized.These images are combined with wind and rain observations from the stepped-frequency microwave radiometer(SFMR),wave simu-lations conducted using a third-generation numerical wave model,WAVEWATCH-III(WW3),and SAR-derived wind information collected from CyclObs winds.The WW3-simulated significant wave height(SWH)is validated against measurements from HY-2B altimeter taken in August and September 2021,yielding a root mean square error(RMSE)of 0.48 m and a correlation coefficient(COR)of 0.88.The SAR-based azimuthal cutoff wavelengths in VV polarization,which quantitatively represent the effect of velocity bunching,are compared with theoretical values calculated using WW3-simulated SWH.A notable relationship is observed between the difference in azimuthal cutoff wavelength and SAR-derived wind speed and WW3-simulated SWH.Analysis results show that the correlation between SAR-based azimuthal cutoff wavelength and SWH is stronger than that with wind and current.Finally,a machine learning algorithm is used to develop an algorithm aimed at simulating the azimuthal cutoff wavelength in TCs,including wind,wave,and incidence angle.This method yields an RMSE of 8.90 m,a COR of 0.91,and a scatter index of 0.04 for VV-polar-ization SAR.展开更多
Chemical oxygen demand(COD)is an important criterion for detecting the emission of pollutants and judging the quality of water.This paper improves the absorption spectrum compensation model for COD and turbidity mixed...Chemical oxygen demand(COD)is an important criterion for detecting the emission of pollutants and judging the quality of water.This paper improves the absorption spectrum compensation model for COD and turbidity mixed solution in the dual-wavelength spectral method based on the Lambert-Beer law additive principle.It compensates for the influence of turbidity on the absorption coefficient of the COD solution at 355 nm by the absorption spectrum coefficient of the mixed solution at 623 nm.This paper establishes a linear relationship model between the absorbance difference of the mixed solution at 355 nm and 623 nm and COD.The experimental determination coefficient R2 of the model is 0.98335,with a relative error of 3.5%and an average error of 0.7 mg/L.The design of the model is simple and easy to systematize,which is of strong significance for practical application.展开更多
This study presents the design of an erbium-doped fiber laser(EDFL) featuring switchable wavelength intervals achieved through the implementation of cascaded and parallel Lyot filters. The proposed laser system utiliz...This study presents the design of an erbium-doped fiber laser(EDFL) featuring switchable wavelength intervals achieved through the implementation of cascaded and parallel Lyot filters. The proposed laser system utilizes a cascaded and parallel configuration of three Lyot filters, facilitated by a polarization beam splitter(PBS) for branch switching. The transmission properties of the filter are analyzed through theoretical modeling and experimental validation using the transmission matrix method. The experimental results are found to be consistent with the theoretical predictions, demonstrating the effectiveness of the proposed design. By adjusting the polarization controllers(PCs), the proposed laser can switch between wavelength spacings of 0.46 nm, 0.27 nm, and 0.76 nm, with a maximum optical signal-to-noise ratio(OSNR) of 38 d B. However, the stability of the laser with a 0.27 nm spacing is not high due to wavelength competition. Power fluctuation for 0.46 nm and 0.76 nm intervals is less than 0.93 d B and 0.78 d B in 1 h, with wavelength fluctuation less than 0.068 nm and 0.19 nm, respectively. This EDFL has the advantages of simple structure, great flexibility, and switchability, which can be applied to fiber optic sensing, wavelength division multiplexing(WDM) networks, and other fields that require a very flexible light source.展开更多
The effect of drive laser wavelength on the growth of ablative Rayleigh–Taylor instability(ARTI)in inertial confinemen fusion(ICF)is studied with two-dimensional numerical simulations.The results show that in the pla...The effect of drive laser wavelength on the growth of ablative Rayleigh–Taylor instability(ARTI)in inertial confinemen fusion(ICF)is studied with two-dimensional numerical simulations.The results show that in the plasma acceleration phase,shorter wavelengths lead to more efficien coupling between the laser and the kinetic energy of the implosion fluid Under the condition that the laser energy coupled to the implosion flui is constant,the ARTI growth rate decreases as the laser wavelength moves toward the extreme ultraviolet band,reaching its minimum value near λ=65 nm,and when the laser wavelength continuously moves toward the X-ray band,the ARTI growth rate increases rapidly.It is found that the results deviate from the theoretical ARTI growth rate.As the laser intensity benchmark increases,the position of the minimum ARTI growth rate shifts toward shorter wavelengths.As the initial sinusoidal perturbation wavenumber decreases,the position of the minimum ARTI growth rate shifts toward longer wavelengths.We believe that the conclusions drawn from the present simulations and analysis will help provide a better understanding of the ICF process and improve the theory of ARTI growth.展开更多
Optogenetics,a technique that employs light for neuromodulation,has revolutionized the study of neural mechanisms and the treatment of neurological disorders due to its high spatiotemporal resolution and cell-type spe...Optogenetics,a technique that employs light for neuromodulation,has revolutionized the study of neural mechanisms and the treatment of neurological disorders due to its high spatiotemporal resolution and cell-type specificity.However,visible light,particularly blue and green light,commonly used in conventional optogenetics,has limited penetration in biological tissue.This limitation necessitates the implantation of optical fibers for light delivery,especially in deep brain regions,leading to tissue damage and experimental constraints.To overcome these challenges,the use of orange-red and infrared light with greater tissue penetration has emerged as a promising approach for tetherless optical neuromodulation.In this review,we provide an overview of the development and applications of tetherless optical neuromodulation methods with long wavelengths.We first discuss the exploration of orange-red wavelength-responsive rhodopsins and their performance in tetherless optical neuromodulation.Then,we summarize two novel tetherless neuromodulation methods using near-infrared light:upconversion nanoparticle-mediated optogenetics and photothermal neuromodulation.In addition,we discuss recent advances in mid-infrared optical neuromodulation.展开更多
Wavelength selective switch(WSS)is the crucial component in the reconfigurable optical add/drop multiplexer(ROADM),which plays a pivotal role in the next-generation all-optical networks.We present a compact architectu...Wavelength selective switch(WSS)is the crucial component in the reconfigurable optical add/drop multiplexer(ROADM),which plays a pivotal role in the next-generation all-optical networks.We present a compact architecture of twin 1×40 liquid crystal on silicon(LCoS)-based WSS,which can be regarded as a 4f system in the wavelength direction and a 2f system in the switching direction.It is designed with theoretical analysis and simulation investigation.Polarization multiplexing is employed for two sources of twin WSS by polarization con-version before the common optical path.The WSS system attains a coupling efficacy exceeding 96%for 90%of the ports through simulation optimization.The 3 dB bandwidth can be achieved by more than 44 GHz at a 50 GHz grid for all 120 channels at all deflection ports.This work establishes a solid foundation for developing high-performance WSS with larger port counts.展开更多
Dual-state emission(DSE)molecules displayed conspicuous fluorescent performance both in solid and solution states.However,the construction of DSE molecules and the regulation of their emission wavelengths remains a gr...Dual-state emission(DSE)molecules displayed conspicuous fluorescent performance both in solid and solution states.However,the construction of DSE molecules and the regulation of their emission wavelengths remains a great challenge.Based on the structure-function relationship of quinolinonitrile-type fluorophores,this work proposed a feasible strategy for modulating their fluorescent properties into DSE via limiting the torsion angle between the quinoline ring and C=C bond in the range of 4.7°to 30°.Based on this strategy,53 compounds were obtained which displayed tunable emission wavelengths from^(3)97 nm to 740 nm in solid-state and from 360 nm to 672 nm in solution.The feasibility of the strategy was supported by a series of theoretical calculations,optical characterizations,and crystal analysis,suggesting the compounds have great potential in imaging living cells and tissues with desired wavelengths.展开更多
The all-optical wavelength conversion using cascaded four-wave mixing(FWM)phenomena with graphene oxide(GO)and a highly nonlinear fiber(HNLF)device is demonstrated experimentally.GO has a strong third-order nonlinear ...The all-optical wavelength conversion using cascaded four-wave mixing(FWM)phenomena with graphene oxide(GO)and a highly nonlinear fiber(HNLF)device is demonstrated experimentally.GO has a strong third-order nonlinear effect and is an excellent nonlinear optical material for nonlinear optical wavelength conversion.The group velocity matching of pump and signal,HNLF,and GO amplification promote the cascaded nonlinear frequency mixing process.From the experimental and analytical results,the maximum spacing between signal and pump is 21 nm,and specifically,the order of cascaded FWM light increases from order 1 to order 2 with increasing GO,and the first-order FWM conversion effi-ciency increases to a maximum of−14.5 dB.To the best of our knowledge,this is the first time that cascaded FWM-based all-optical wavelength conversion in HNLF-GO with wide wavelength selectivity is investigated with combined pump and signal light.Our findings not only provide an effective method for achieving all-optical wavelength conversion in cascaded FWM but also offer the possibility of fabricating high-performance nonlinear optical devices.展开更多
A vacuum ultraviolet(VUV)spectroscopy with a focal length of 1 m has been engineered specifically for observing edge impurity emissions in Experimental Advanced Superconducting Tokamak(EAST).In this study,wavelength c...A vacuum ultraviolet(VUV)spectroscopy with a focal length of 1 m has been engineered specifically for observing edge impurity emissions in Experimental Advanced Superconducting Tokamak(EAST).In this study,wavelength calibration for the VUV spectroscopy is achieved utilizing a zinc lamp.The grating angle and charge-coupled device(CCD)position are carefully calibrated for different wavelength positions.The wavelength calibration of the VUV spectroscopy is crucial for improving the accuracy of impurity spectral data,and is required to identify more impurity spectral lines for impurity transport research.Impurity spectra of EAST plasmas have also been obtained in the wavelength range of 50–300 nm with relatively high spectral resolution.It is found that the impurity emissions in the edge region are still dominated by low-Z impurities,such as carbon,oxygen,and nitrogen,albeit with the application of fulltungsten divertors on the EAST tokamak.展开更多
In this paper, a Wavelength Division Multiplexing (WDM) network model based on the equivalent networks is described, and wavelength-dependent equivalent arc, equivalent networks, equivalent multicast tree and some oth...In this paper, a Wavelength Division Multiplexing (WDM) network model based on the equivalent networks is described, and wavelength-dependent equivalent arc, equivalent networks, equivalent multicast tree and some other terms are presented. Based on this model and relevant Routing and Wavelength Assign- ment (RWA) strategy, a unicast RWA algorithm and a multicast RWA algorithm are presented. The wave- length-dependent equivalent arc expresses the schedule of local RWA and the equivalent network expresses the whole topology of WDM optical networks, so the two algorithms are of the flexibility in RWA and the optimi- zation of the whole problem. The theoretic analysis and simulation results show the two algorithms are of the stronger capability and the lower complexity than the other existing algorithms for RWA problem, and the complexity of the two algorithms are only related to the scale of the equivalent networks. Finally, we prove the two algorithms’ feasibility and the one-by-one corresponding relation between the equivalent multicast tree and original multicast tree, and point out the superiorities and drawbacks of the two algorithms respectively.展开更多
Internet and broadband applications driven by data traffic demand have become key dri- vers for satellite constellations. The key technology to satisfy the high capacity requirements between satellites is optical sate...Internet and broadband applications driven by data traffic demand have become key dri- vers for satellite constellations. The key technology to satisfy the high capacity requirements between satellites is optical satellite networks by means of wavelength division multiplexing inter- satellite links （ISLs） with wavelength routing （WDM-OSN）. Due to the limited optical amplifier bandwidth onboard the satellite, it is important to minimize the wavelength requirements to provi- sion requests. However, ISLs should be dynamically established and deleted for each satellite according to its visible satellites. Furthermore, different link assignments will result in different topologies, hence yielding different routings and wavelength assignments. Thus, a perfect match model-based link assignment scheme （LAS-PMM） is proposed to design an appropriate topology such that shorter path could be routed and less wavelengths could be assigned for each ISL along the path. Finally, simulation results show that in comparison to the regular Manhattan street net- work （MSN） topology, wavelength requirements and average end-to-end delay based on the topol- ogy generated by LAS-PMM could be reduced by 24.8% and 12.4%, respectively.展开更多
We applied near-infrared(NIR)spectroscopy with chemometrics for the rapid and reagent-fee analysis of serum urea nitrogen(SUN).The modeling is based on the average effect of multiple sample partitions to achieve param...We applied near-infrared(NIR)spectroscopy with chemometrics for the rapid and reagent-fee analysis of serum urea nitrogen(SUN).The modeling is based on the average effect of multiple sample partitions to achieve parameter selection with stability.A multiparameter optimization platform with Norris derivative filter-partial least squares(Norris-PLS)was developed to select the most suitable mode(d=2,s=33,g=15).Using equidistant combination PLS(EC-PLS)with four parameters(initial wavelength I,number of wavelengths N,number of wavelength gaps G and latent variables LV),we performed wavelength screening after eliminating high-absorption wavebands.The optimal EC-PLS parameters were I=1228 nm,N=26,G=16 and LV=12.The root-mean square error(SEP),correlation coefficient(R_(p))for prediction and ratio of performance-to-deviation(RPD)for validation were 1.03 mmol L^(-1),0.992 and 7.6,respectively.We proposed the wavelength step-by-step phase-out PLS(WSP-PLS)to remove redun-dant wavelengths in the top 100 EC-PLS models with improved prediction performance.The combination of 19 wavelengths was identifed as the optimal model for SUN.The SEP,Rp and RPD in validation were 1.01 mmol L^(-1),0.992 and 7.7,respectively.The prediction effect and wavelength complexity were better than those of EC-PIS.Our results showed that NIR spectroscopy combined with the EC-PLS and WSP-PLS methods enabled the high-precision analysis ofSUN.WSP-PLS is a secondary optimization method that can further optimize any wavelength moc odel obtained through other continuous or discrete strategies to establish a simple and better model.展开更多
The systematical and scalable frameworks were provided for estimating the blocking probabilities under asynchronous traffic in optical burst switching(OBS) nodes with limited wavelength conversion capability(LWCC) . T...The systematical and scalable frameworks were provided for estimating the blocking probabilities under asynchronous traffic in optical burst switching(OBS) nodes with limited wavelength conversion capability(LWCC) . The relevant system architectures of limited range and limited number of wavelength converters(WCs) deployed by a share-per-fiber(SPF) mode were developed,and the novel theoretical analysis of node blocking probability was derived by combining the calculation of discouraged arrival rate in a birth-death process and two-dimensional Markov chain model of SPF. The simulation results on single node performance verify the accuracy and effectiveness of the analysis models. Under most scenarios,it is difficult to distinguish the plots generated by the analysis and simulation. As the conversion degree increases,the accuracy of the analysis model worsens slightly. However,the utmost error on burst loss probability is far less than one order of magnitude and hence,still allows for an accurate estimate. Some results are of actual significance to the construction of next-generation commercial OBS backbones.展开更多
We design an 850 nm tunable vertical-cavity surface-emitting laser(VCSEL)structure using an internal-cavity sub-wavelength grating.The use of such a tuning structure allows for wider wavelength tuning range and more s...We design an 850 nm tunable vertical-cavity surface-emitting laser(VCSEL)structure using an internal-cavity sub-wavelength grating.The use of such a tuning structure allows for wider wavelength tuning range and more stable single-polarization as compared to conventional tunable VCSELs.The features of the internal-cavity grating effect on the wavelength tuning and polarization characteristics of the tunable VCSEL are analyzed.The simulation results show that the largest wavelength tuning range achieves 44.2 nm,and the maximum orthogonal polarization suppression ratio(OPSR)is 33.4 dB(TE-type)and 38.7 dB(TM-type).展开更多
After reviewing three different definitions of mode field diameter of single-mode fibers, coupled efficiency calculation methods associated with lateral offset, longitude separation and wavelength, the effects produce...After reviewing three different definitions of mode field diameter of single-mode fibers, coupled efficiency calculation methods associated with lateral offset, longitude separation and wavelength, the effects produced by them, and the influences of splicing defects were discussed in detail. The regularities of the effects were studied according to the first order derivation of couple efficiency formula, and a simplified formula for couple efficiency calculation was presented under the circumstance of slight misalignment, with respect to wavelength, 2, and in a good agreement with the theoretical model. The simplified formula provides a new but simple approach to evaluate wavelength dependent couple efficiency of single-mode fibers. Theoretical analyses and numerical calculations show that, when those defects exist, the wavelength produces additional effects on the couple loss that growth of wavelength causes an increase on the couple efficiency for the lateral offset or longitude separation whereas lessens the couple efficiency due to angular misalignment or mode fields mismatching, and that the wavelength degrades the couple efficiency distinctly when λ≥2.5 μm whereas it distorts the couple slightly in range of λ≤2λ≤2 μm.展开更多
Our recently proposed three-step method showed the promising potential to improve the accuracy of relative wavelength response(RWR) characterization in the wavelength-modulation spectroscopy(WMS) over the commonly use...Our recently proposed three-step method showed the promising potential to improve the accuracy of relative wavelength response(RWR) characterization in the wavelength-modulation spectroscopy(WMS) over the commonly used summation method.A detailed comparison of the three-step method and the summation method,for the wavelength-scanned WMS gas-sensing,was performed with different laser parameters(modulation indexes and scan indexes) and gas properties(pressures and concentrations).Simulation results show that the accuracy of the predicted gas parameters is strongly limited by the RWR characterization with large modulation index and high gas pressure conditions.Both fitting residuals of RWR and errors of predicted gas parameters from the recently proposed three-step method are nearly 2 orders of magnitude smaller than those from the summation method.In addition,the three-step method is further improved by introducing a coupling term for the 2^(nd) harmonic amplitude.Experiments with CO_(2) absorption transition at 6976.2026 cm^(-1) were conducted and validated the simulation analysis.The modified-three-step method presents an improved accuracy in RWR description with at least 5% smaller fitting residual for all conditions compared with the three-step method,although the deviation of the deduced CO_(2) concentrations between these two methods does not exceed 0.2%.展开更多
Wavelength modulation technique （WMT） and wavelength sweep technique （WST） are introduced into intra-cavity absorption gas sensors （ICAGS） for low concentration gas detection. The optimized parameters of the sys...Wavelength modulation technique （WMT） and wavelength sweep technique （WST） are introduced into intra-cavity absorption gas sensors （ICAGS） for low concentration gas detection. The optimized parameters of the system maximizing the signal-to-noise ratio （SNR） are found. Calibration of acetylene concentration and gas recognition are both realized.展开更多
Compact passive silicon photonic devices with high performance are always desired for future largescale photonic integration.Inverse design provides a promising approach to realize new-generation photonic devices,whil...Compact passive silicon photonic devices with high performance are always desired for future largescale photonic integration.Inverse design provides a promising approach to realize new-generation photonic devices,while it is still very challenging to realize complex photonic devices for most inverse designs reported previously due to the limits of computational resources.Here,we present the realization of several representative advanced passive silicon photonic devices with complex optimization,including a sixchannel mode(de)multiplexer,a broadband 90 deg hybrid,and a flat-top wavelength demultiplexer.These devices are designed inversely by optimizing a subwavelength grating(SWG)region and the multimode excitation and the multimode interference are manipulated.Particularly,such SWG structures are more fabrication-friendly than those random nanostructures introduced in previous inverse designs.The realized photonic devices have decent performances in a broad bandwidth with a low excess loss of<1 dB,which is much lower than that of previous inverse-designed devices.The present inverse design strategy shows great effectiveness for designing advanced photonic devices with complex requirements(which is beyond the capability of previous inverse designs)by using affordable computational resources.展开更多
基金supported by the National Natural Science Foundation of China(12322210,12172351,92252202,and 12388101)the Fundamental Research Funds for the Central Universities.
文摘Rod-airfoil interaction noise becomes a major issue in some aeronautical applications.The design of four wavy leading edges(WLEs)with varying wavelengths,bioinspired by the tubercles on humpback whales’flippers,aims to mitigate far-field noise.Among these cases,a reduction in the wavelength is found to be advantageous for noise suppression,with the smallest wavelength case achieving a maximum noise reduction of 1.9 dB.Furthermore,the noise radiation induced by WLEs is suppressed mainly at medium frequencies.The theory of multiprocess aeroacoustics is applied to reveal their underlying mechanisms.The dominant factor is the source cutoff effect,which significantly decreases the source strength on hills.Additionally,spanwise decoherence with phase interference serves as another crucial mechanism,particularly for reducing mid-frequency noise.
基金supported in part by the National Natural Science Foundation of China under Grants U21B2005,62201105,62331017,U24B20134,62222103,and 62025105in part by the Chongqing Municipal Education Commission under Grants KJQN202400621,KJQN202100643,and KJZDK202400608+1 种基金in part by the China Postdoctoral Science Foundation under Grant 2021M700563in part by the Chongqing Postdoctoral Funding Project under Grant 2021XM3052。
文摘Multi-band optical networks are a potential technology for increasing network capacity.However,the strong interference and non-uniformity between wavelengths in multi-band optical networks have become a bottleneck restricting the transmission capacity of multi-band optical networks.To overcome these challenges,it is particularly important to implement optical power optimization targeting wavelength differences.Therefore,based on the generalized Gaussian noise model,we first formulate an optimization model for the problems of routing,modulation format,wavelength,and power allocation in C+L+S multi-band optical networks.Our objective function is to maximize the average link capacity of the network while ensuring that the Optical Signal-to-Noise(OSNR)threshold of the service request is not exceeded.Next,we propose a NonLinear Interferenceaware(NLI-aware)routing,modulation format,wavelength,and power allocation algorithm.Finally,we conduct simulations under different test conditions.The simulation results indicate that our algorithm can effectively reduce the blocking probability by 23.5%and improve the average link capacity by 3.78%in C+L+S multi-band optical networks.
基金supported by the National Natural Science Foundation of China(Nos.42076238,42376174)the Natural Science Foundation of Shanghai(No.23ZR1426900).
文摘The purpose of this study is to analyze the impact of upper ocean dynamics on velocity bunching,represented by az-imuthal cutoff wavelength(i.e.,sea surface wind,wave,and current).In this study,over 1400 dual-polarized(vertical-vertical(VV)and vertical-horizontal(VH))Sentinel-1(S-1)synthetic aperture radar(SAR)images collected in tropical cyclones(TC)are utilized.These images are combined with wind and rain observations from the stepped-frequency microwave radiometer(SFMR),wave simu-lations conducted using a third-generation numerical wave model,WAVEWATCH-III(WW3),and SAR-derived wind information collected from CyclObs winds.The WW3-simulated significant wave height(SWH)is validated against measurements from HY-2B altimeter taken in August and September 2021,yielding a root mean square error(RMSE)of 0.48 m and a correlation coefficient(COR)of 0.88.The SAR-based azimuthal cutoff wavelengths in VV polarization,which quantitatively represent the effect of velocity bunching,are compared with theoretical values calculated using WW3-simulated SWH.A notable relationship is observed between the difference in azimuthal cutoff wavelength and SAR-derived wind speed and WW3-simulated SWH.Analysis results show that the correlation between SAR-based azimuthal cutoff wavelength and SWH is stronger than that with wind and current.Finally,a machine learning algorithm is used to develop an algorithm aimed at simulating the azimuthal cutoff wavelength in TCs,including wind,wave,and incidence angle.This method yields an RMSE of 8.90 m,a COR of 0.91,and a scatter index of 0.04 for VV-polar-ization SAR.
基金supported by the Youth Project of National Natural Science Foundation of China(No.61505145)the Tianjin Science and Technology Commissioner Project(No.20YDTPJC02010)+1 种基金the Tianjin Municipal Education Commission(No.2021KJ003)the Tianjin Zhonghuan Tianjia Electronics Company(No.HX20193)。
文摘Chemical oxygen demand(COD)is an important criterion for detecting the emission of pollutants and judging the quality of water.This paper improves the absorption spectrum compensation model for COD and turbidity mixed solution in the dual-wavelength spectral method based on the Lambert-Beer law additive principle.It compensates for the influence of turbidity on the absorption coefficient of the COD solution at 355 nm by the absorption spectrum coefficient of the mixed solution at 623 nm.This paper establishes a linear relationship model between the absorbance difference of the mixed solution at 355 nm and 623 nm and COD.The experimental determination coefficient R2 of the model is 0.98335,with a relative error of 3.5%and an average error of 0.7 mg/L.The design of the model is simple and easy to systematize,which is of strong significance for practical application.
基金supported by the Primary Research and Development Plan of Zhejiang Province (No.2023C03014)the Key Research and Development Program of Zhejiang Province (No.2022C03037)。
文摘This study presents the design of an erbium-doped fiber laser(EDFL) featuring switchable wavelength intervals achieved through the implementation of cascaded and parallel Lyot filters. The proposed laser system utilizes a cascaded and parallel configuration of three Lyot filters, facilitated by a polarization beam splitter(PBS) for branch switching. The transmission properties of the filter are analyzed through theoretical modeling and experimental validation using the transmission matrix method. The experimental results are found to be consistent with the theoretical predictions, demonstrating the effectiveness of the proposed design. By adjusting the polarization controllers(PCs), the proposed laser can switch between wavelength spacings of 0.46 nm, 0.27 nm, and 0.76 nm, with a maximum optical signal-to-noise ratio(OSNR) of 38 d B. However, the stability of the laser with a 0.27 nm spacing is not high due to wavelength competition. Power fluctuation for 0.46 nm and 0.76 nm intervals is less than 0.93 d B and 0.78 d B in 1 h, with wavelength fluctuation less than 0.068 nm and 0.19 nm, respectively. This EDFL has the advantages of simple structure, great flexibility, and switchability, which can be applied to fiber optic sensing, wavelength division multiplexing(WDM) networks, and other fields that require a very flexible light source.
基金supported by the National Natural Science Foundation of China(NSFC)(Grant Nos.12074399,12204500,and 12004403)the Key Projects of the Intergovernmental International Scientifi and Technological Innovation Cooperation(Grant No.2021YFE0116700)+1 种基金the Shanghai Natural Science Foundation(Grant No.20ZR1464400)the Shanghai Sailing Program(Grant No.22YF1455300)。
文摘The effect of drive laser wavelength on the growth of ablative Rayleigh–Taylor instability(ARTI)in inertial confinemen fusion(ICF)is studied with two-dimensional numerical simulations.The results show that in the plasma acceleration phase,shorter wavelengths lead to more efficien coupling between the laser and the kinetic energy of the implosion fluid Under the condition that the laser energy coupled to the implosion flui is constant,the ARTI growth rate decreases as the laser wavelength moves toward the extreme ultraviolet band,reaching its minimum value near λ=65 nm,and when the laser wavelength continuously moves toward the X-ray band,the ARTI growth rate increases rapidly.It is found that the results deviate from the theoretical ARTI growth rate.As the laser intensity benchmark increases,the position of the minimum ARTI growth rate shifts toward shorter wavelengths.As the initial sinusoidal perturbation wavenumber decreases,the position of the minimum ARTI growth rate shifts toward longer wavelengths.We believe that the conclusions drawn from the present simulations and analysis will help provide a better understanding of the ICF process and improve the theory of ARTI growth.
基金supported by China Postdoctoral Science Foundation(2022M723356),"From 0 to 1"Original Innovation Project of the Basic Frontier Scientific Research Program of the Chinese Academy of Sciences(29J20-015-Ⅲ)Chinese Academy of Sciences 100 Talents Project:Research on Task oriented Functional Brain Development of Infants(29J20-052-Ⅲ)Natural Science Basic Research Plan in Shaanxi Province of China(2022JQ544).
文摘Optogenetics,a technique that employs light for neuromodulation,has revolutionized the study of neural mechanisms and the treatment of neurological disorders due to its high spatiotemporal resolution and cell-type specificity.However,visible light,particularly blue and green light,commonly used in conventional optogenetics,has limited penetration in biological tissue.This limitation necessitates the implantation of optical fibers for light delivery,especially in deep brain regions,leading to tissue damage and experimental constraints.To overcome these challenges,the use of orange-red and infrared light with greater tissue penetration has emerged as a promising approach for tetherless optical neuromodulation.In this review,we provide an overview of the development and applications of tetherless optical neuromodulation methods with long wavelengths.We first discuss the exploration of orange-red wavelength-responsive rhodopsins and their performance in tetherless optical neuromodulation.Then,we summarize two novel tetherless neuromodulation methods using near-infrared light:upconversion nanoparticle-mediated optogenetics and photothermal neuromodulation.In addition,we discuss recent advances in mid-infrared optical neuromodulation.
基金This work was supported by ZTE Industry⁃University⁃Institute Coopera⁃tion Funds under Grant No.IA20230614004.
文摘Wavelength selective switch(WSS)is the crucial component in the reconfigurable optical add/drop multiplexer(ROADM),which plays a pivotal role in the next-generation all-optical networks.We present a compact architecture of twin 1×40 liquid crystal on silicon(LCoS)-based WSS,which can be regarded as a 4f system in the wavelength direction and a 2f system in the switching direction.It is designed with theoretical analysis and simulation investigation.Polarization multiplexing is employed for two sources of twin WSS by polarization con-version before the common optical path.The WSS system attains a coupling efficacy exceeding 96%for 90%of the ports through simulation optimization.The 3 dB bandwidth can be achieved by more than 44 GHz at a 50 GHz grid for all 120 channels at all deflection ports.This work establishes a solid foundation for developing high-performance WSS with larger port counts.
基金supported by the National Natural Science Foundation of China(Nos.22077099 and 22171223)The Innovation Capability Support Program of Shaanxi(Nos.2023-CX-TD-75 and 2022KJXX-32)+5 种基金the Scientific and Technological Innovation Team of Shaanxi Province(No.2022TD-36)the Technology Innovation Leading Program of Shaanxi(No.2023KXJ-209)the Natural Science Basic Research Program of Shaanxi(Nos.2023-JC-YB-141 and 2022JQ-151)Young Talent Fund of Association for Science and Technology in Shaanxi,China(No.SWYY202206)the Shaanxi Fundamental Science Research Project for Chemistry&Biology(Nos.22JHZ010 and 22JHQ080)the Yan’an City Science and Technology Project(No.2022SLZDCY-002)。
文摘Dual-state emission(DSE)molecules displayed conspicuous fluorescent performance both in solid and solution states.However,the construction of DSE molecules and the regulation of their emission wavelengths remains a great challenge.Based on the structure-function relationship of quinolinonitrile-type fluorophores,this work proposed a feasible strategy for modulating their fluorescent properties into DSE via limiting the torsion angle between the quinoline ring and C=C bond in the range of 4.7°to 30°.Based on this strategy,53 compounds were obtained which displayed tunable emission wavelengths from^(3)97 nm to 740 nm in solid-state and from 360 nm to 672 nm in solution.The feasibility of the strategy was supported by a series of theoretical calculations,optical characterizations,and crystal analysis,suggesting the compounds have great potential in imaging living cells and tissues with desired wavelengths.
基金supported by the National Natural Science Foundation of China(Nos.61775032,11604042)the Fundamental Research Funds for the Central Universities(Nos.N2104022,N2004021)the"111 Project"(No.B16009).
文摘The all-optical wavelength conversion using cascaded four-wave mixing(FWM)phenomena with graphene oxide(GO)and a highly nonlinear fiber(HNLF)device is demonstrated experimentally.GO has a strong third-order nonlinear effect and is an excellent nonlinear optical material for nonlinear optical wavelength conversion.The group velocity matching of pump and signal,HNLF,and GO amplification promote the cascaded nonlinear frequency mixing process.From the experimental and analytical results,the maximum spacing between signal and pump is 21 nm,and specifically,the order of cascaded FWM light increases from order 1 to order 2 with increasing GO,and the first-order FWM conversion effi-ciency increases to a maximum of−14.5 dB.To the best of our knowledge,this is the first time that cascaded FWM-based all-optical wavelength conversion in HNLF-GO with wide wavelength selectivity is investigated with combined pump and signal light.Our findings not only provide an effective method for achieving all-optical wavelength conversion in cascaded FWM but also offer the possibility of fabricating high-performance nonlinear optical devices.
基金partially supported by National Natural Science Foundation of China(Nos.U23A2077,12175278,12205072)the National Magnetic Confinement Fusion Science Program of China(Nos.2019YFE0304002,2018YFE0303103)+2 种基金the Comprehensive Research Facility for Fusion Technology Program of China(No.2018-000052-73-01-001228)Major Science and Technology Infrastructure Maintenance and Reconstruction Projects of the Chinese Academy of Sciences(2021)the University Synergy Innovation Program of Anhui Province(No.GXXT2021-029)。
文摘A vacuum ultraviolet(VUV)spectroscopy with a focal length of 1 m has been engineered specifically for observing edge impurity emissions in Experimental Advanced Superconducting Tokamak(EAST).In this study,wavelength calibration for the VUV spectroscopy is achieved utilizing a zinc lamp.The grating angle and charge-coupled device(CCD)position are carefully calibrated for different wavelength positions.The wavelength calibration of the VUV spectroscopy is crucial for improving the accuracy of impurity spectral data,and is required to identify more impurity spectral lines for impurity transport research.Impurity spectra of EAST plasmas have also been obtained in the wavelength range of 50–300 nm with relatively high spectral resolution.It is found that the impurity emissions in the edge region are still dominated by low-Z impurities,such as carbon,oxygen,and nitrogen,albeit with the application of fulltungsten divertors on the EAST tokamak.
基金Supported by the Natrual Science Foundation of Shaanxi (No.2004A02) and Outstanding Scholar Project of P. R. China (2002).
文摘In this paper, a Wavelength Division Multiplexing (WDM) network model based on the equivalent networks is described, and wavelength-dependent equivalent arc, equivalent networks, equivalent multicast tree and some other terms are presented. Based on this model and relevant Routing and Wavelength Assign- ment (RWA) strategy, a unicast RWA algorithm and a multicast RWA algorithm are presented. The wave- length-dependent equivalent arc expresses the schedule of local RWA and the equivalent network expresses the whole topology of WDM optical networks, so the two algorithms are of the flexibility in RWA and the optimi- zation of the whole problem. The theoretic analysis and simulation results show the two algorithms are of the stronger capability and the lower complexity than the other existing algorithms for RWA problem, and the complexity of the two algorithms are only related to the scale of the equivalent networks. Finally, we prove the two algorithms’ feasibility and the one-by-one corresponding relation between the equivalent multicast tree and original multicast tree, and point out the superiorities and drawbacks of the two algorithms respectively.
基金supported by the National Natural Science Foundation of China(Nos.61471238,61433009)
文摘Internet and broadband applications driven by data traffic demand have become key dri- vers for satellite constellations. The key technology to satisfy the high capacity requirements between satellites is optical satellite networks by means of wavelength division multiplexing inter- satellite links （ISLs） with wavelength routing （WDM-OSN）. Due to the limited optical amplifier bandwidth onboard the satellite, it is important to minimize the wavelength requirements to provi- sion requests. However, ISLs should be dynamically established and deleted for each satellite according to its visible satellites. Furthermore, different link assignments will result in different topologies, hence yielding different routings and wavelength assignments. Thus, a perfect match model-based link assignment scheme （LAS-PMM） is proposed to design an appropriate topology such that shorter path could be routed and less wavelengths could be assigned for each ISL along the path. Finally, simulation results show that in comparison to the regular Manhattan street net- work （MSN） topology, wavelength requirements and average end-to-end delay based on the topol- ogy generated by LAS-PMM could be reduced by 24.8% and 12.4%, respectively.
基金supported by the Science and Technology Project of Guangdong Province of China(Nos.2014A020213016,2014A020212445)the University-enterprise Joint Research Project"Intelligent detection network technology joint research centre"(No.40115031).
文摘We applied near-infrared(NIR)spectroscopy with chemometrics for the rapid and reagent-fee analysis of serum urea nitrogen(SUN).The modeling is based on the average effect of multiple sample partitions to achieve parameter selection with stability.A multiparameter optimization platform with Norris derivative filter-partial least squares(Norris-PLS)was developed to select the most suitable mode(d=2,s=33,g=15).Using equidistant combination PLS(EC-PLS)with four parameters(initial wavelength I,number of wavelengths N,number of wavelength gaps G and latent variables LV),we performed wavelength screening after eliminating high-absorption wavebands.The optimal EC-PLS parameters were I=1228 nm,N=26,G=16 and LV=12.The root-mean square error(SEP),correlation coefficient(R_(p))for prediction and ratio of performance-to-deviation(RPD)for validation were 1.03 mmol L^(-1),0.992 and 7.6,respectively.We proposed the wavelength step-by-step phase-out PLS(WSP-PLS)to remove redun-dant wavelengths in the top 100 EC-PLS models with improved prediction performance.The combination of 19 wavelengths was identifed as the optimal model for SUN.The SEP,Rp and RPD in validation were 1.01 mmol L^(-1),0.992 and 7.7,respectively.The prediction effect and wavelength complexity were better than those of EC-PIS.Our results showed that NIR spectroscopy combined with the EC-PLS and WSP-PLS methods enabled the high-precision analysis ofSUN.WSP-PLS is a secondary optimization method that can further optimize any wavelength moc odel obtained through other continuous or discrete strategies to establish a simple and better model.
基金Project(60632010) supported by the National Natural Science Foundation of China
文摘The systematical and scalable frameworks were provided for estimating the blocking probabilities under asynchronous traffic in optical burst switching(OBS) nodes with limited wavelength conversion capability(LWCC) . The relevant system architectures of limited range and limited number of wavelength converters(WCs) deployed by a share-per-fiber(SPF) mode were developed,and the novel theoretical analysis of node blocking probability was derived by combining the calculation of discouraged arrival rate in a birth-death process and two-dimensional Markov chain model of SPF. The simulation results on single node performance verify the accuracy and effectiveness of the analysis models. Under most scenarios,it is difficult to distinguish the plots generated by the analysis and simulation. As the conversion degree increases,the accuracy of the analysis model worsens slightly. However,the utmost error on burst loss probability is far less than one order of magnitude and hence,still allows for an accurate estimate. Some results are of actual significance to the construction of next-generation commercial OBS backbones.
基金the Jilin Science and Technology Development Plan,China(Grant Nos.20180519018JH and 20190302052GX)Jilin Education Department“135”Science and Technology,China(Grant No.JJKH20190543KJ)+1 种基金the National Natural Science Foundation of China(Grant No.11474038)the Key Project of Equipment Pre-Research Fund of China(Grant No.61404140103)。
文摘We design an 850 nm tunable vertical-cavity surface-emitting laser(VCSEL)structure using an internal-cavity sub-wavelength grating.The use of such a tuning structure allows for wider wavelength tuning range and more stable single-polarization as compared to conventional tunable VCSELs.The features of the internal-cavity grating effect on the wavelength tuning and polarization characteristics of the tunable VCSEL are analyzed.The simulation results show that the largest wavelength tuning range achieves 44.2 nm,and the maximum orthogonal polarization suppression ratio(OPSR)is 33.4 dB(TE-type)and 38.7 dB(TM-type).
基金Projects（51005074, 91123035） supported by the National Natural Science Foundation of China Project（201021200077） supported by the Frontier Research Program of Central South University, China
文摘After reviewing three different definitions of mode field diameter of single-mode fibers, coupled efficiency calculation methods associated with lateral offset, longitude separation and wavelength, the effects produced by them, and the influences of splicing defects were discussed in detail. The regularities of the effects were studied according to the first order derivation of couple efficiency formula, and a simplified formula for couple efficiency calculation was presented under the circumstance of slight misalignment, with respect to wavelength, 2, and in a good agreement with the theoretical model. The simplified formula provides a new but simple approach to evaluate wavelength dependent couple efficiency of single-mode fibers. Theoretical analyses and numerical calculations show that, when those defects exist, the wavelength produces additional effects on the couple loss that growth of wavelength causes an increase on the couple efficiency for the lateral offset or longitude separation whereas lessens the couple efficiency due to angular misalignment or mode fields mismatching, and that the wavelength degrades the couple efficiency distinctly when λ≥2.5 μm whereas it distorts the couple slightly in range of λ≤2λ≤2 μm.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.51906120 and 11972213)China Postdoctoral Science Foundation(Grant Nos.2018M640125 and 2019T120088)the National Basic Research Program of China(Grant No.2016YFC0201104)。
文摘Our recently proposed three-step method showed the promising potential to improve the accuracy of relative wavelength response(RWR) characterization in the wavelength-modulation spectroscopy(WMS) over the commonly used summation method.A detailed comparison of the three-step method and the summation method,for the wavelength-scanned WMS gas-sensing,was performed with different laser parameters(modulation indexes and scan indexes) and gas properties(pressures and concentrations).Simulation results show that the accuracy of the predicted gas parameters is strongly limited by the RWR characterization with large modulation index and high gas pressure conditions.Both fitting residuals of RWR and errors of predicted gas parameters from the recently proposed three-step method are nearly 2 orders of magnitude smaller than those from the summation method.In addition,the three-step method is further improved by introducing a coupling term for the 2^(nd) harmonic amplitude.Experiments with CO_(2) absorption transition at 6976.2026 cm^(-1) were conducted and validated the simulation analysis.The modified-three-step method presents an improved accuracy in RWR description with at least 5% smaller fitting residual for all conditions compared with the three-step method,although the deviation of the deduced CO_(2) concentrations between these two methods does not exceed 0.2%.
基金supported by the National Natural Science Foundation of China under Grant No. 60577013the New Century Support Program for Talented Young Teachers in Universities, MOE (Ministry of Education of China), China
文摘Wavelength modulation technique （WMT） and wavelength sweep technique （WST） are introduced into intra-cavity absorption gas sensors （ICAGS） for low concentration gas detection. The optimized parameters of the system maximizing the signal-to-noise ratio （SNR） are found. Calibration of acetylene concentration and gas recognition are both realized.
基金supported by the National Major Research and Development Program(Grant No.2018YFB2200200)the National Science Fund for Distinguished Young Scholars(Grant No.61725503)+3 种基金the National Natural Science Foundation of China(Grant Nos.62175216,61961146003,91950205)Zhejiang Provincial Natural Science Foundation(Grant No.LR22F050001)The Fundamental Research Funds for the Central UniversitiesThe Leading Innovative and Entrepreneur Team Introduction Program of Zhejiang(Grant No.2021R01001).
文摘Compact passive silicon photonic devices with high performance are always desired for future largescale photonic integration.Inverse design provides a promising approach to realize new-generation photonic devices,while it is still very challenging to realize complex photonic devices for most inverse designs reported previously due to the limits of computational resources.Here,we present the realization of several representative advanced passive silicon photonic devices with complex optimization,including a sixchannel mode(de)multiplexer,a broadband 90 deg hybrid,and a flat-top wavelength demultiplexer.These devices are designed inversely by optimizing a subwavelength grating(SWG)region and the multimode excitation and the multimode interference are manipulated.Particularly,such SWG structures are more fabrication-friendly than those random nanostructures introduced in previous inverse designs.The realized photonic devices have decent performances in a broad bandwidth with a low excess loss of<1 dB,which is much lower than that of previous inverse-designed devices.The present inverse design strategy shows great effectiveness for designing advanced photonic devices with complex requirements(which is beyond the capability of previous inverse designs)by using affordable computational resources.
