Developing electrocatalysts to inhibit polysulfide shuttling and expedite sulfur species conversion is vital for the evolution of Lithium-sulfur(Li-S)batteries.This work provides a facile strategy to design an intimat...Developing electrocatalysts to inhibit polysulfide shuttling and expedite sulfur species conversion is vital for the evolution of Lithium-sulfur(Li-S)batteries.This work provides a facile strategy to design an intimate heterostructure of MIL-88A@CdS as a sulfur electrocatalyst combining high sulfur adsorption and accelerated polysulfide conversion.The MIL-88A can give a region of high-ordered polysulfide adsorption,whereas the CdS is an effective nanoreactor for the sulfur reduction reaction(SRR).Notedly,the significant size difference between MIL-88A and CdS enables the unique heterostructure interactions.The largesize MIL-88A ensures a uniform distribution of CdS nanoparticles as a substrate.This configuration facilitates control of the initial polysulfide adsorption position relative to its final deposition site as lithium sulfide.The heterostructure also demonstrates rapid transport and efficient conversion of lithium polysulfides.Consequently,the Li-S battery with MIL-88A@CdS heterostructure modified separator delivers exceptional performance,achieving an areal capacity exceeding 6 mAh cm^(−2),an excellent rate capability of 980 mAh g^(−1) at 5 C,and notable cycling stability in a 2 Ah pouch cell over 100 cycles.This work is significant for elucidating the relationship between heterostructure and electrocatalytic performance,providing great insights for material design aimed at highly efficient future electrocatalysts in practical applications.展开更多
By adopting in-line lensless Fourier setup and phase-shifting technique, we recorded the phase-shifting digital hologram at short distance. As the Fresnel diffraction condition is no longer valid, the convolution appr...By adopting in-line lensless Fourier setup and phase-shifting technique, we recorded the phase-shifting digital hologram at short distance. As the Fresnel diffraction condition is no longer valid, the convolution approach is chosen for the reconstruction. However, the simulated reference wave for the reconstruction would suffer from severe undersampling due to the comparatively large pixel size. To solve this problem, sine-interpolation is introduced to get the pixel-size of the hologram reduced prior to the reconstruction. The experimental results show that an object image of high fidelity is obtained with this method.展开更多
The dark soliton pulse with spectral sideband is experimentally observed in a dispersion-managed ail-fiber ring laser with net negative cavity group velocity dispersion.We find that,for single or multiple dark soliton...The dark soliton pulse with spectral sideband is experimentally observed in a dispersion-managed ail-fiber ring laser with net negative cavity group velocity dispersion.We find that,for single or multiple dark solitons,the spectral sidebands always appear and exhibit asymmetric characteristics which are similar to bright solitons.The experimental measurements of spectral sideband positions are carried out and the results are in good agreement with the calculated values.Our results show that spectral sideband effect is also an intrinsic feature of a dark soliton fiber laser.展开更多
Employing the technique of symmetry reduction of analytic method, we solve the Ginzburg-Landau equation with varying nonlinear, dispersion, gain coefficients, and gain dispersion which originates from the limiting eff...Employing the technique of symmetry reduction of analytic method, we solve the Ginzburg-Landau equation with varying nonlinear, dispersion, gain coefficients, and gain dispersion which originates from the limiting effect of transition bandwidth in the realistic doped fibres. The parabolic asymptotic self-similar analytical solutions in gain medium of the normal GVD is found for the first time to our best knowledge. The evolution of pulse amplitude, strict linear phase chirp and effective temporal width are given with self-similarity results in longitudinal nonlinearity distribution and longitudinal gain fibre. These analytical solutions are in good agreement with the numerical simulations. Furthermore, we theoretically prove that pulse evolution has the characteristics of parabolic asymptotic self-similarity in doped ions dipole gain fibres.展开更多
Both the negativity of Wigner function and the phase sensitivity of an SU(1,1) interferometer are investigated in this paper. In the case that the even coherent state and squeezed vacuum state are input into the inter...Both the negativity of Wigner function and the phase sensitivity of an SU(1,1) interferometer are investigated in this paper. In the case that the even coherent state and squeezed vacuum state are input into the interferometer, the Heisenberg limit can be approached with parity detection. At the same time, the negativity volume of Wigner function of detection mode comes entirely from the input state and varies periodically with the encoding phase. In addition, the negativity volume of Wigner function is positively correlated with the phase sensitivity of the SU(1,1) interferometer. The positive correlation may mean that the non-classicality indicated by negative Wigner function is a kind of resource that can verify some related research results of phase estimation.展开更多
In view of the ＂Comment on ＇Ported from Self- Similar Analytic Solutions of Ginzburg-Landau Equation with Varying Coefficients＇＂, and referring to Refs., we reply as follows：
A flashlamp-pumped Cr：LiSAF laser system with a voltage controlled Q-switch structure in the cavity is designed. A dual-wavelength and dual-pulse tunable laser output is gained. The relation of laser output behavior ...A flashlamp-pumped Cr：LiSAF laser system with a voltage controlled Q-switch structure in the cavity is designed. A dual-wavelength and dual-pulse tunable laser output is gained. The relation of laser output behavior with input energy is studied experimentally. The output is dual-pulsed with the energy of the 32m J/pulse producing the total output energy of 64mJ and the pulse width is about 27ns at 850nm. Then, we use one LBO crystal as the frequency doubling crystal to obtain a dual wavelength （448.1 nm and 449.15nm） and dual pulse laser. The output for one wavelength is about 10.3mJ and the line width is less than 0.02nm.展开更多
By adjusting the waveguide length ratio, we study the extraordinary characteristics of electromagnetic waves propagating in one-dimensional(1D) parity-time-symmetric(PT-symmetric) two-segment-connected triangular opti...By adjusting the waveguide length ratio, we study the extraordinary characteristics of electromagnetic waves propagating in one-dimensional(1D) parity-time-symmetric(PT-symmetric) two-segment-connected triangular optical waveguide networks with perfect and broken integer waveguide length ratios respectively. It is found that the number and the corresponding frequencies of the extremum spontaneous PT-symmetric breaking points are dependent on the waveguide length ratio. Near the extremum breaking points, ultrastrong extraordinary transmissions are created and the maximal can arrive at, respectively, 2.4079 × 10^14 and 4.3555 × 10^13 in both kinds of networks. However, bidirectional invisibility can only be produced by the networks with broken integer waveguide length ratio, whose mechanism is explained in detail from the perspective of photonic band structure. The findings of this work can be useful optical characteristic control in the fabrication of PT-symmetric optical waveguide networks, which possesses great potential in designing optical amplifiers,optical energy saver devices, and special optical filters.展开更多
We propose and numerically simulate a nanoscale electro-optic (EO) switch based on a metal-insulator-metal structure composed of a strip waveguide and two side-coupled cavities filled with an EO material of 4-dimethyl...We propose and numerically simulate a nanoscale electro-optic (EO) switch based on a metal-insulator-metal structure composed of a strip waveguide and two side-coupled cavities filled with an EO material of 4-dimethylamino-N-methyl-4-stilbazolium tosylate,using the finite difference time domain method.It is found that the structure can be operated as an EO switch at a wavelength of 945nm,with a modulation depth of 27dB,a half-wave voltage of 5.3 V and a switching time of about 50 ps.展开更多
Flat supercontinuum in the telecommunication wave bands of E+S+C is generated by coupling a train of femtosecond pulses generated by a mode-locked Ti:sapphire laser into the fundameutal mode of a photonic crystal fibe...Flat supercontinuum in the telecommunication wave bands of E+S+C is generated by coupling a train of femtosecond pulses generated by a mode-locked Ti:sapphire laser into the fundameutal mode of a photonic crystal fiber with central holes fabricated in our lab. The pulse experiences the anomalous dispersion regime,and the soliton dynamic effect plays an important role in supercontinuum generation.The output spectrum in the wavelength range of 1360 1565nm does not include significant ripples due to higher pump peak power,and the normalized intensity shows less fluctuation.展开更多
The visible light communication(VLC)system employs large viewing divergence angle light-emitting diode(LED)to realize illumination and communication simultaneously,so the geometric loss of optical power may reach tens...The visible light communication(VLC)system employs large viewing divergence angle light-emitting diode(LED)to realize illumination and communication simultaneously,so the geometric loss of optical power may reach tens of decibels,moreover,considering the gain reduction of the LED at high frequency,signal power at the receiver will be too weak.To overcome these drawbacks,in this paper,a low output impedance power driver amplifier is presented to provide enough power to drive a medium power commercial LED used at the end of the optical transmitter.A125 Mbit/s real-time communication with illumination and communication angle of 130°has been achieved at a distance of 3 m,the bit error rate(BER)is 3.13×10-11 at a divergence angle of LED of 0°and 1.21×10-6 at a communication angle of 130°.Experimental results indicated that this VLC system can be used for illumination and communication simultaneously.展开更多
This study is to report a ZnSe quantum dot with a large two-photon absorption cross section and good biocompatibility,which can be used in bioimaging.Fluorescence emission at 410 nm is observed in the quantum dot unde...This study is to report a ZnSe quantum dot with a large two-photon absorption cross section and good biocompatibility,which can be used in bioimaging.Fluorescence emission at 410 nm is observed in the quantum dot under 760-nm laser excitation.These biocompatible quantum dots exhibit a two-photon cross-section of 9.1×105 GM(1 GM=10-50 cm4·s/photon).Two-photon excited laser scanning microscopic images show that cells co-cultured with ZnSe quantum dots are found in the blue channel at a fluorescence intensity that is 14.5 times that of control cells not cocultured with quantum dots.After incubating zebrafish larvae with ZnSe quantum dots for 24 h,the fluorescence intensity of the yolk sac stimulated by ultraviolet light is 2.9 times that of the control group.The proposed material shows a great potential application in biological imaging.展开更多
The commercialization of a polymer membrane H2-O2 fuel cell and its widespread use call for the development of cost-effective oxygen reduction reaction(ORR)nonplatinum group metal(NPGM)catalysts.Nevertheless,to meet t...The commercialization of a polymer membrane H2-O2 fuel cell and its widespread use call for the development of cost-effective oxygen reduction reaction(ORR)nonplatinum group metal(NPGM)catalysts.Nevertheless,to meet the requests for the real-world fuel cell application and replacing platinum catalysts,it still needs to address some challenges for NPGM catalysts regarding the sluggish ORR kinetics in the cathode and their poor durability in acidic environment.In response to these issues,numerous efforts have been made to study NPGM catalysts both theoretically and experimentally,developed these into the atomically dispersed coordinated metal-nitrogen-carbon(M-N-C)form over the past decades.In this review,we present a comprehensive summary of recent advancements on NPGM catalysts with high activity and durability.Catalyst design strategies in terms of optimizing active-site density and enhancing catalyst stability against demetalization and carbon corrosion are highlighted.It is also emphasized the importance of understanding the mechanisms and principles behind those strategies through a combination of theoretical modeling and experimental work.Especially,further understanding the mechanisms related to the active-site structure and the formation process of the single-atom active site under pyrolysis conditions is critical for active-site engineering.Optimizing the active-site distance is the basic principle for improving catalyst activity through increasing the catalyst active-site density.Theoretical studies for the catalyst deactivation mechanism and modeling stable active-site structures provide both mechanisms and principles to improve the NPGM catalyst durability.Finally,currently remained challenges and perspectives in the future on designing high-performance atomically dispersed NPGM catalysts toward fuel cell application are discussed.展开更多
Blue-shifted dispersive waves(DWs)are efficiently generated from the red-shifted solitons by coupling the 120 fs pulses into the fundamental mode of the multi-knots of a photonic crystal fiber cladding.When the femtos...Blue-shifted dispersive waves(DWs)are efficiently generated from the red-shifted solitons by coupling the 120 fs pulses into the fundamental mode of the multi-knots of a photonic crystal fiber cladding.When the femtosecond pulses at the wavelength of 825 nm and the average power of 300 mW are coupled into knots 1–3,the conversion efficiencyηDW of 32%and bandwidth BDW of 50 nm are obtained.The ultrashort pulses generated by the DWs can be tunable over the whole visible wavelength by adjusting the wavelengths of the pump pulses coupled into different knots.It can be believed that this widely wavelength-tunable ultrashort visible pulse source has important applications in ultrafast photonics and resonant Raman scattering.展开更多
We present a tumour cell growth process model including a multiplicative coloured noise and an additive coloured noise correlated. How the noise cross-correlation intensity λ and correlation time T can affect the ste...We present a tumour cell growth process model including a multiplicative coloured noise and an additive coloured noise correlated. How the noise cross-correlation intensity λ and correlation time T can affect the steady state properties of tumour cell growth model are discussed by solving an approximative Fokker-Planck equation. It is found that the increase of noise correlation time T can cause the tumour cell number increasing, but the increase of multiplicative noise intensity can cause the tumour cell number extinction. We also find that the increase of cross-correlation intensity λ in the case of 0 〈 λ 〈 1 can cause the tumour cell number extinction, whereas increase of cross-correlation intensity λ in the case of λ 〈 0 can cause the tumour cell number increasing.展开更多
We investigate the effects of the Casimir force on the output properties of a hybrid optomechanical system. In this system, a nanosphere is fixed on the movable-mirror side of the standard optomechanical system, and t...We investigate the effects of the Casimir force on the output properties of a hybrid optomechanical system. In this system, a nanosphere is fixed on the movable-mirror side of the standard optomechanical system, and the nanosphere interacts with the movable-mirror via the Casimir force, which depends on the mirror–sphere separation. In the presence of the probe and control fields, we analyze the transmission coefficient and the group delay of the field-component with the frequency of the probe field. We also study the transmission intensity of the field-component with the frequency of a newly generated four-wave mixing(FWM) field. By manipulating the Casimir force, we find that a tunable slow light can be realized for the field-component with the frequency of the probe field, and the intensity spectrum of the FWM field can be enhanced and shifted effectively.展开更多
We present the generation of six-particle Greenberger Horne-Zeilinger （GHZ） states via deterministic entanglement concentration and generalize the scheme to the case of 2N particles. We show that arbitrary 2N-partic...We present the generation of six-particle Greenberger Horne-Zeilinger （GHZ） states via deterministic entanglement concentration and generalize the scheme to the case of 2N particles. We show that arbitrary 2N-particle GHZ states can be obtained with certain probability via entanglement concentration. This may provide a new perspective for the preparation of multi-particle GHZ states. This study is also an exploration on the theory of deterministic entanglement concentration.展开更多
The generation of high-energy dual-wavelength domain wall pulse with a low repetition rate is demonstrated in a highly nonlinear fiber （HNLF）-based fiber ring laser. By introducing the intracavity birefringence-indu...The generation of high-energy dual-wavelength domain wall pulse with a low repetition rate is demonstrated in a highly nonlinear fiber （HNLF）-based fiber ring laser. By introducing the intracavity birefringence-induced spectral filtering effect, the dual-wavelength lasing operation can be achieved. In order to enhance the cross coupling effect between the two lasing beams for domain wall pulse formation, a 215-m HNLF is incorporated into the laser cavity. Experimentally, it is found that the dual-wavelength domain wall pulse with a repetition rate of 77.67 kHz could be efficiently obtained through simply rotating the polarization controller （PC）. At a maximum pump power of 322 mW, the 655-nJ single pulse energy in cavity is obtained. The proposed configuration provides a simpler and more efficient way to generate high energy pulse with a low repetition rate.展开更多
We report on the generation of dual-wavelength dissipative solitons in a passively mode-locked fibre laser with a net normal dispersion using the nonlinear polarization rotation （NPR） technique. Taking the intrinsic...We report on the generation of dual-wavelength dissipative solitons in a passively mode-locked fibre laser with a net normal dispersion using the nonlinear polarization rotation （NPR） technique. Taking the intrinsic advantage of the intracavity birefringence-induced spectral filtering effect in the NPR-based ring laser cavity, the dual-wavelength dissipative solitons are obtained. In addition, the wavelength separation and the lasing location of the dual-wavelength solitons can be flexibly tuned by changing the orientation of the polarization controller.展开更多
An Yba＋/Al3＋-codoped microstructured optical fibre is prepared based on photonic crystal fibre technology. The characteristic spectra of preforms and fibres are experimentally investigated. The results show that und...An Yba＋/Al3＋-codoped microstructured optical fibre is prepared based on photonic crystal fibre technology. The characteristic spectra of preforms and fibres are experimentally investigated. The results show that under a 971 nm excitation, besides the known infrared fluorescence luminescence around 1050 nm, a blue luminescence peak at 486 nm is obtained. Moreover, an unexpected emission peak at 730 nm is also observed. The photoluminescence mechanism of an Yba＋/Al3＋-codoped microstructured optical fibre is discussed. The emission peak at 486 nm is attributed to the cooperative upconversion resulting from pairs of Yb3＋ ions, and the emission peak around 730 nm is ascribed to the stimulated Raman scattering because of nonlinear effects of microstructured optical fibre. The Yba＋/Al3＋-codoped microstructured optical fibre is promising for varieties of applications from laser printing and optical recording to cancer treatments, such as photodynamic therapy.展开更多
基金supported by the Natural Science Foundation of China(22309179)the Natural Science Foundation of China(12404049)+4 种基金Natural Science Foundation of Ningxia(2023AAC01003)Guangdong Basic and Applied Basic Research Foundation(2021A1515110156,2022A1515010724,2023A1515110521,2023B1515120095,2024A1515011260)Science and Technology Program of Guangzhou(No.2019050001)the Outstanding Youth Project of Guangdong Natural Science Foundation(2021B1515020051)Dalian Revitalization Talents Program(No.2022RG01).
文摘Developing electrocatalysts to inhibit polysulfide shuttling and expedite sulfur species conversion is vital for the evolution of Lithium-sulfur(Li-S)batteries.This work provides a facile strategy to design an intimate heterostructure of MIL-88A@CdS as a sulfur electrocatalyst combining high sulfur adsorption and accelerated polysulfide conversion.The MIL-88A can give a region of high-ordered polysulfide adsorption,whereas the CdS is an effective nanoreactor for the sulfur reduction reaction(SRR).Notedly,the significant size difference between MIL-88A and CdS enables the unique heterostructure interactions.The largesize MIL-88A ensures a uniform distribution of CdS nanoparticles as a substrate.This configuration facilitates control of the initial polysulfide adsorption position relative to its final deposition site as lithium sulfide.The heterostructure also demonstrates rapid transport and efficient conversion of lithium polysulfides.Consequently,the Li-S battery with MIL-88A@CdS heterostructure modified separator delivers exceptional performance,achieving an areal capacity exceeding 6 mAh cm^(−2),an excellent rate capability of 980 mAh g^(−1) at 5 C,and notable cycling stability in a 2 Ah pouch cell over 100 cycles.This work is significant for elucidating the relationship between heterostructure and electrocatalytic performance,providing great insights for material design aimed at highly efficient future electrocatalysts in practical applications.
基金Project supported by the National Natural Science Foundation of China (Grant Nos 60747001 and 60467003)
文摘By adopting in-line lensless Fourier setup and phase-shifting technique, we recorded the phase-shifting digital hologram at short distance. As the Fresnel diffraction condition is no longer valid, the convolution approach is chosen for the reconstruction. However, the simulated reference wave for the reconstruction would suffer from severe undersampling due to the comparatively large pixel size. To solve this problem, sine-interpolation is introduced to get the pixel-size of the hologram reduced prior to the reconstruction. The experimental results show that an object image of high fidelity is obtained with this method.
基金Supported by the National Natural Science Foundation of China under Grant No 11074078the Specialized Research Fund for the Doctoral Program of Higher Education of China under Grant No 20094407110002the Foundation for Distinguished Young Talents in Higher Education of Guangdong Province under Grant No C10183.
文摘The dark soliton pulse with spectral sideband is experimentally observed in a dispersion-managed ail-fiber ring laser with net negative cavity group velocity dispersion.We find that,for single or multiple dark solitons,the spectral sidebands always appear and exhibit asymmetric characteristics which are similar to bright solitons.The experimental measurements of spectral sideband positions are carried out and the results are in good agreement with the calculated values.Our results show that spectral sideband effect is also an intrinsic feature of a dark soliton fiber laser.
基金Supported by the Natural Science Foundation of Guangdong Province under Grant No 04010397.
文摘Employing the technique of symmetry reduction of analytic method, we solve the Ginzburg-Landau equation with varying nonlinear, dispersion, gain coefficients, and gain dispersion which originates from the limiting effect of transition bandwidth in the realistic doped fibres. The parabolic asymptotic self-similar analytical solutions in gain medium of the normal GVD is found for the first time to our best knowledge. The evolution of pulse amplitude, strict linear phase chirp and effective temporal width are given with self-similarity results in longitudinal nonlinearity distribution and longitudinal gain fibre. These analytical solutions are in good agreement with the numerical simulations. Furthermore, we theoretically prove that pulse evolution has the characteristics of parabolic asymptotic self-similarity in doped ions dipole gain fibres.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11574092,61775062,61378012,91121023,and 60978009)the National Basic Research Program of China(Grant No.2013CB921804)the Innovation Project of Graduate School of South China Normal University(Grant No.2017LKXM088)
文摘Both the negativity of Wigner function and the phase sensitivity of an SU(1,1) interferometer are investigated in this paper. In the case that the even coherent state and squeezed vacuum state are input into the interferometer, the Heisenberg limit can be approached with parity detection. At the same time, the negativity volume of Wigner function of detection mode comes entirely from the input state and varies periodically with the encoding phase. In addition, the negativity volume of Wigner function is positively correlated with the phase sensitivity of the SU(1,1) interferometer. The positive correlation may mean that the non-classicality indicated by negative Wigner function is a kind of resource that can verify some related research results of phase estimation.
基金Supported by the Natural Science Foundation of Guangdong Province under Grant No 04010397.
文摘In view of the ＂Comment on ＇Ported from Self- Similar Analytic Solutions of Ginzburg-Landau Equation with Varying Coefficients＇＂, and referring to Refs., we reply as follows：
基金Supported by the Swiss National Science Foundation （PICI2-106865）, the National Natural Science Foundation of China （60411130595）, and Guangdong Natural Science Foundation （8251063101000006）.
文摘A flashlamp-pumped Cr：LiSAF laser system with a voltage controlled Q-switch structure in the cavity is designed. A dual-wavelength and dual-pulse tunable laser output is gained. The relation of laser output behavior with input energy is studied experimentally. The output is dual-pulsed with the energy of the 32m J/pulse producing the total output energy of 64mJ and the pulse width is about 27ns at 850nm. Then, we use one LBO crystal as the frequency doubling crystal to obtain a dual wavelength （448.1 nm and 449.15nm） and dual pulse laser. The output for one wavelength is about 10.3mJ and the line width is less than 0.02nm.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11674107,61475049,11775083,61875057,61774062,and 61771205)Special Funds for the Cultivation of Guangdong College Students’ Scientific and Techonlogical Innovation,China(Grant No.pdjhb0139)
文摘By adjusting the waveguide length ratio, we study the extraordinary characteristics of electromagnetic waves propagating in one-dimensional(1D) parity-time-symmetric(PT-symmetric) two-segment-connected triangular optical waveguide networks with perfect and broken integer waveguide length ratios respectively. It is found that the number and the corresponding frequencies of the extremum spontaneous PT-symmetric breaking points are dependent on the waveguide length ratio. Near the extremum breaking points, ultrastrong extraordinary transmissions are created and the maximal can arrive at, respectively, 2.4079 × 10^14 and 4.3555 × 10^13 in both kinds of networks. However, bidirectional invisibility can only be produced by the networks with broken integer waveguide length ratio, whose mechanism is explained in detail from the perspective of photonic band structure. The findings of this work can be useful optical characteristic control in the fabrication of PT-symmetric optical waveguide networks, which possesses great potential in designing optical amplifiers,optical energy saver devices, and special optical filters.
文摘We propose and numerically simulate a nanoscale electro-optic (EO) switch based on a metal-insulator-metal structure composed of a strip waveguide and two side-coupled cavities filled with an EO material of 4-dimethylamino-N-methyl-4-stilbazolium tosylate,using the finite difference time domain method.It is found that the structure can be operated as an EO switch at a wavelength of 945nm,with a modulation depth of 27dB,a half-wave voltage of 5.3 V and a switching time of about 50 ps.
基金Supported by the Key Program of the National Natural Science Foundation of China under Grant No 60637010the National Basic Research Program of China under Grant Nos 2010CB327604 and 2010CB327604Qinhuangdao Science and Technology Research and Development Program under Grant No 201101A093.
文摘Flat supercontinuum in the telecommunication wave bands of E+S+C is generated by coupling a train of femtosecond pulses generated by a mode-locked Ti:sapphire laser into the fundameutal mode of a photonic crystal fiber with central holes fabricated in our lab. The pulse experiences the anomalous dispersion regime,and the soliton dynamic effect plays an important role in supercontinuum generation.The output spectrum in the wavelength range of 1360 1565nm does not include significant ripples due to higher pump peak power,and the normalized intensity shows less fluctuation.
基金supported by the Science of Technology Program of Guangdong Province(No.2015B010112002)the Science Technology Program of Guangzhou(No.201804010166)。
文摘The visible light communication(VLC)system employs large viewing divergence angle light-emitting diode(LED)to realize illumination and communication simultaneously,so the geometric loss of optical power may reach tens of decibels,moreover,considering the gain reduction of the LED at high frequency,signal power at the receiver will be too weak.To overcome these drawbacks,in this paper,a low output impedance power driver amplifier is presented to provide enough power to drive a medium power commercial LED used at the end of the optical transmitter.A125 Mbit/s real-time communication with illumination and communication angle of 130°has been achieved at a distance of 3 m,the bit error rate(BER)is 3.13×10-11 at a divergence angle of LED of 0°and 1.21×10-6 at a communication angle of 130°.Experimental results indicated that this VLC system can be used for illumination and communication simultaneously.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.61774062 and U20A20206)the Science and Techology Program of Guangzhou City,China(Grant No.2019050001)the Natural Science Foundation of Guangdong Province,China(Grant Nos.2018A030313854 and2016A030308010)。
文摘This study is to report a ZnSe quantum dot with a large two-photon absorption cross section and good biocompatibility,which can be used in bioimaging.Fluorescence emission at 410 nm is observed in the quantum dot under 760-nm laser excitation.These biocompatible quantum dots exhibit a two-photon cross-section of 9.1×105 GM(1 GM=10-50 cm4·s/photon).Two-photon excited laser scanning microscopic images show that cells co-cultured with ZnSe quantum dots are found in the blue channel at a fluorescence intensity that is 14.5 times that of control cells not cocultured with quantum dots.After incubating zebrafish larvae with ZnSe quantum dots for 24 h,the fluorescence intensity of the yolk sac stimulated by ultraviolet light is 2.9 times that of the control group.The proposed material shows a great potential application in biological imaging.
基金Guangdong High Level Innovation Research Institute,Grant/Award Numbers:2021B0909050001,2021B0909050001。
文摘The commercialization of a polymer membrane H2-O2 fuel cell and its widespread use call for the development of cost-effective oxygen reduction reaction(ORR)nonplatinum group metal(NPGM)catalysts.Nevertheless,to meet the requests for the real-world fuel cell application and replacing platinum catalysts,it still needs to address some challenges for NPGM catalysts regarding the sluggish ORR kinetics in the cathode and their poor durability in acidic environment.In response to these issues,numerous efforts have been made to study NPGM catalysts both theoretically and experimentally,developed these into the atomically dispersed coordinated metal-nitrogen-carbon(M-N-C)form over the past decades.In this review,we present a comprehensive summary of recent advancements on NPGM catalysts with high activity and durability.Catalyst design strategies in terms of optimizing active-site density and enhancing catalyst stability against demetalization and carbon corrosion are highlighted.It is also emphasized the importance of understanding the mechanisms and principles behind those strategies through a combination of theoretical modeling and experimental work.Especially,further understanding the mechanisms related to the active-site structure and the formation process of the single-atom active site under pyrolysis conditions is critical for active-site engineering.Optimizing the active-site distance is the basic principle for improving catalyst activity through increasing the catalyst active-site density.Theoretical studies for the catalyst deactivation mechanism and modeling stable active-site structures provide both mechanisms and principles to improve the NPGM catalyst durability.Finally,currently remained challenges and perspectives in the future on designing high-performance atomically dispersed NPGM catalysts toward fuel cell application are discussed.
基金Supported by the National Basic Research Program of China(2010CB327605,2010CB328300)the Key Grant of Ministry of Education(109015)+3 种基金the Program for New Century Excellent Talents in University(NECT-11-0596)Beijing Nova Program(2011066)the Fundamental Research Funds for the Central Universities(2011RC008,2011RC0404)Open Fund of State Key Laboratory of Information Photonics and Optical Communications(Beijing University of Posts and Telecommunications).
文摘Blue-shifted dispersive waves(DWs)are efficiently generated from the red-shifted solitons by coupling the 120 fs pulses into the fundamental mode of the multi-knots of a photonic crystal fiber cladding.When the femtosecond pulses at the wavelength of 825 nm and the average power of 300 mW are coupled into knots 1–3,the conversion efficiencyηDW of 32%and bandwidth BDW of 50 nm are obtained.The ultrashort pulses generated by the DWs can be tunable over the whole visible wavelength by adjusting the wavelengths of the pump pulses coupled into different knots.It can be believed that this widely wavelength-tunable ultrashort visible pulse source has important applications in ultrafast photonics and resonant Raman scattering.
基金Supported by the National Natural Science Foundation of China under Grant Nos 10347108 and 30470495, and the Guangdong Provincial Natural Science Foundation under Grant No 021707.
文摘We present a tumour cell growth process model including a multiplicative coloured noise and an additive coloured noise correlated. How the noise cross-correlation intensity λ and correlation time T can affect the steady state properties of tumour cell growth model are discussed by solving an approximative Fokker-Planck equation. It is found that the increase of noise correlation time T can cause the tumour cell number increasing, but the increase of multiplicative noise intensity can cause the tumour cell number extinction. We also find that the increase of cross-correlation intensity λ in the case of 0 〈 λ 〈 1 can cause the tumour cell number extinction, whereas increase of cross-correlation intensity λ in the case of λ 〈 0 can cause the tumour cell number increasing.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11574092,61775062,61378012,91121023,and 60978009)the National Basic Research Program of China(Grant No.2013CB921804)the Innovation Project of Graduate School of South China Normal University(Grant No.2017LKXM090)
文摘We investigate the effects of the Casimir force on the output properties of a hybrid optomechanical system. In this system, a nanosphere is fixed on the movable-mirror side of the standard optomechanical system, and the nanosphere interacts with the movable-mirror via the Casimir force, which depends on the mirror–sphere separation. In the presence of the probe and control fields, we analyze the transmission coefficient and the group delay of the field-component with the frequency of the probe field. We also study the transmission intensity of the field-component with the frequency of a newly generated four-wave mixing(FWM) field. By manipulating the Casimir force, we find that a tunable slow light can be realized for the field-component with the frequency of the probe field, and the intensity spectrum of the FWM field can be enhanced and shifted effectively.
基金Supported by the National Basic Research Programme of China under Grant No 2007CB307001, and the Natural Science Foundation of Guangdong Province under Grant No 06029431.
文摘We present the generation of six-particle Greenberger Horne-Zeilinger （GHZ） states via deterministic entanglement concentration and generalize the scheme to the case of 2N particles. We show that arbitrary 2N-particle GHZ states can be obtained with certain probability via entanglement concentration. This may provide a new perspective for the preparation of multi-particle GHZ states. This study is also an exploration on the theory of deterministic entanglement concentration.
基金supported by the National Natural Science Foundation of China(Grant Nos.11074078,61378036,61307058,11304101,and 61177077)the Specialized Research Fund for the Doctoral Program of Higher Education,China(Grant No.20094407110002)the Ph.D.Start-up Fund of the Natural Science Foundation of Guangdong Province,China(Grant No.S2013040016320)
文摘The generation of high-energy dual-wavelength domain wall pulse with a low repetition rate is demonstrated in a highly nonlinear fiber （HNLF）-based fiber ring laser. By introducing the intracavity birefringence-induced spectral filtering effect, the dual-wavelength lasing operation can be achieved. In order to enhance the cross coupling effect between the two lasing beams for domain wall pulse formation, a 215-m HNLF is incorporated into the laser cavity. Experimentally, it is found that the dual-wavelength domain wall pulse with a repetition rate of 77.67 kHz could be efficiently obtained through simply rotating the polarization controller （PC）. At a maximum pump power of 322 mW, the 655-nJ single pulse energy in cavity is obtained. The proposed configuration provides a simpler and more efficient way to generate high energy pulse with a low repetition rate.
基金supported by the National Natural Science Foundation of China(Grant No.11074078)the Specialized Research Fund for the Doctoral Program of Higher Education,China(Grant No.20094407110002)+1 种基金the Foundation for Distinguished Young Talents in Higher Education of Guangdong,China(Grant No.C10183)the Key Program for Scientific and Technological Innovations of Higher Education Institutes in Guangdong Province,China(Grant No.cxzdlOll)
文摘We report on the generation of dual-wavelength dissipative solitons in a passively mode-locked fibre laser with a net normal dispersion using the nonlinear polarization rotation （NPR） technique. Taking the intrinsic advantage of the intracavity birefringence-induced spectral filtering effect in the NPR-based ring laser cavity, the dual-wavelength dissipative solitons are obtained. In addition, the wavelength separation and the lasing location of the dual-wavelength solitons can be flexibly tuned by changing the orientation of the polarization controller.
基金Project supported by the State Key Program of National Natural Science Foundation of China (Grant No. 60637010)the Major Basic Research Development Program of China (Grant No. 2010CB327604)
文摘An Yba＋/Al3＋-codoped microstructured optical fibre is prepared based on photonic crystal fibre technology. The characteristic spectra of preforms and fibres are experimentally investigated. The results show that under a 971 nm excitation, besides the known infrared fluorescence luminescence around 1050 nm, a blue luminescence peak at 486 nm is obtained. Moreover, an unexpected emission peak at 730 nm is also observed. The photoluminescence mechanism of an Yba＋/Al3＋-codoped microstructured optical fibre is discussed. The emission peak at 486 nm is attributed to the cooperative upconversion resulting from pairs of Yb3＋ ions, and the emission peak around 730 nm is ascribed to the stimulated Raman scattering because of nonlinear effects of microstructured optical fibre. The Yba＋/Al3＋-codoped microstructured optical fibre is promising for varieties of applications from laser printing and optical recording to cancer treatments, such as photodynamic therapy.
