A Weyl node is characterized by its chirality and tilt.We develop a theory of how nth-order nonlinear optical conductivity behaves under transformations of anisotropic tensor and tilt, which clarifies how chirality-de...A Weyl node is characterized by its chirality and tilt.We develop a theory of how nth-order nonlinear optical conductivity behaves under transformations of anisotropic tensor and tilt, which clarifies how chirality-dependent and-independent parts of optical conductivity transform under the reversal of tilt and chirality.Built on this theory, we propose ferromagnetic Mn Bi2Te4as a magnetoelectrically regulated, terahertz optical device, by magnetoelectrically switching the chiralitydependent and-independent DC photocurrents.These results are useful for creating nonlinear optical devices based on the topological Weyl semimetals.展开更多
The quantum metric manifested as the Riemannian metric in the parameter space of Bloch bands,characterizes the topology and geometry of quantum states.The second harmonic generation(SHG),as one of the fundamental nonl...The quantum metric manifested as the Riemannian metric in the parameter space of Bloch bands,characterizes the topology and geometry of quantum states.The second harmonic generation(SHG),as one of the fundamental nonlinear optical responses that links geometry of optical transitions to physical observables,despite being widely studied in various materials,its relation to quantum metric,especially in the dynamical regime,stays obscure.展开更多
Bulk materials were synthesized by the Bridgman technique using the elements Cu, Ga, Se. These samples were characterized by Energy Dispersive Spectrometry (EDS) to determine the elemental composition, as well as by X...Bulk materials were synthesized by the Bridgman technique using the elements Cu, Ga, Se. These samples were characterized by Energy Dispersive Spectrometry (EDS) to determine the elemental composition, as well as by X-ray diffraction for structure, hot point probe method for type of conductivity. Optical response (Photoconductivity) and Photoluminescence (PL) and PL-excitation (PLE) at temperatures from 4.2 to 77 K were also used to estimate the band-gap energy of Cu-Ga<sub>3</sub>Se<sub>5</sub>. They show a nearly perfect stoechiometry and present p-type conductivity. CuGa<sub>3</sub>Se<sub>5</sub> either have an Ordered Defect Chalcopyrite structure (ODC), or an Ordered Vacancy Chalcopyrite structure (OVC). The gap energy obtained by Photoconductivity and Photoluminescence (PL) for the different samples is 1.85 eV. Studying the variation of the gap as a function of the temperature shows that the transition is a D-A type. The defects that appear are probably Ga<sub>Cu</sub>.展开更多
Optically active and inactive hyperbranched polymers with specific thermoresponsive behaviours in water were reported.Through two steps hyperbranched polyethylenimine（HPEI） polymers terminated with different amount ...Optically active and inactive hyperbranched polymers with specific thermoresponsive behaviours in water were reported.Through two steps hyperbranched polyethylenimine（HPEI） polymers terminated with different amount of D-phenylalanine（D-Phe）,L-phenylalanine（L-Phe） or DL-phenylalanine（DL-Phe） were prepared and characterized.The analyses on the solution properties by turbidimetry,dynamic light scattering,fluorescence probe and 1H-NMR demonstrated that all the polymers exhibited specific thermoresponsive behaviours in water,including：（1） In the dilute polymer concentration region,increasing the polymer concentration led to the increase of phase transition temperature;（2） The optically inactive thermoresponsive hyperbranched polymers showed a higher cloud-point temperature（Tcp） than their corresponding optically active ones in a relatively higher polymer concentration;（3） At the same polymer concentration the hydrophobic groups of the optically inactive HPEI-DL-Phe formed more perfect hydrophobic domain than those of the optically active HPEI-L-Phe and HPEI-D-Phe.展开更多
Dear Editor,Multiple evanescent white dot syndrome （MEWDS） was first described in 1984 as a rare, acute, unilateral,multifocal retinochoroidal disorder, typically affecting young myopic women. Previous studies with ...Dear Editor,Multiple evanescent white dot syndrome （MEWDS） was first described in 1984 as a rare, acute, unilateral,multifocal retinochoroidal disorder, typically affecting young myopic women. Previous studies with fluorescein angiography （FA） and electrophysiology suggested that MEWDS to be a disease in the retinal pigment epithelium （RPE） or outer retina, while recent studies with spectral- domain optical coherence tomography （SD-OCT） suggested it may be an outer retinal disease due to observation of hyperreflective material in outer retina and subtle disruptionsof the ellipsoid zone without RPE disruption.展开更多
Graphite carbon nitride(g-C_(3)N_(4))attracts wide-ranging research interest due to its extraordinary physicochemical properties and promising applications ranging from heterogeneous catalysis to fuel cells.In this wo...Graphite carbon nitride(g-C_(3)N_(4))attracts wide-ranging research interest due to its extraordinary physicochemical properties and promising applications ranging from heterogeneous catalysis to fuel cells.In this work,we design different g-C_(3)N_(4)-based quantum dots(g CNQDs),carry out a systematic study of optical properties,and elucidate the shape selectivity,composite nanostructure,and outfield effect.In particular,composites of g CNQDs and metal nanochains present excellent optical response,making it applicable to bioimaging,nano-plasma devices,and metalloenzyme in infrared light related fields.Besides,QDs which original bridging nitrogen atoms are replaced by amino(–NH_(2)),hydroxyl(–OH),and methyl(–CH_(3))functional groups respectively,have excellent spectral selectivity in the deep ultraviolet region.More interestingly,in the study of the laser interaction with materials,the g CNQDs exhibit extremely high stability and light corrosion resistance.Phase transition from insulation to metal is observed under the critical condition of about 5 e V intensity or 337 nm wavelength.All provided theoretical support for designs and applications in g-C_(3)N_(4)quantum devices.展开更多
We present a theoretical study on the effects of intense laser field(ILF)and static electric field on the linear and nonlinear optical properties of a cylindrical quantum dot with Rosen-Morse axial potential under the...We present a theoretical study on the effects of intense laser field(ILF)and static electric field on the linear and nonlinear optical properties of a cylindrical quantum dot with Rosen-Morse axial potential under the framework of effective mass and parabolic band approximations.This study also takes into account the effects of the structure parameters(η,V1,and R).The analytical expressions of the linear,third-order nonlinear and total optical absorption coefficients(TOACs)and the relative refractive index changes(RRICs)are obtained by using the compact-densitymatrix approach.The results of numerical calculations show that the resonant peak position of the TOACs and RRICs shifts towards lower energies and the magnitude of the peak increases with the effect of the static electric field and ILF.In addition,it is observed that while the resonant energies of the TOACs and RRICs of system shift towards the higher(lower)energies with the enhancement ofη,V1,they decrease with the augmentation of R.Thus,the findings of this study show that the optical properties of the structure can be adjusted by changing the magnitude of structure parameters and applied external fields.展开更多
Nonlinear optical （NLO） properties of anatase TiO2 with nanostructures of nanopaxticle （NP）, nanowire （NW） and annealed nanowire （NWA） are studied by open-aperture and closed-aperture Z-scan techniques with a ...Nonlinear optical （NLO） properties of anatase TiO2 with nanostructures of nanopaxticle （NP）, nanowire （NW） and annealed nanowire （NWA） are studied by open-aperture and closed-aperture Z-scan techniques with a fem- tosecond pulsed laser at wavelengths of 532 nm and 780 nm simultaneously. At 532 nm, when increasing excitation intensity, NLO absorption of TiO2 NPs transforms from saturable absorption to reverse-saturable absorption. However, NWs and NWAs exhibit the opposite change. At 780nm, all samples show reverse-saturable absorption, but have different sensitivities to excitation intensity. Due to the larger surface-to-volume ratio of NPs and less defects of NWAs by annealing, nonlinear optical absorption coet^icients follow the order NPs≥ NWs≥ NWAs. The results also show that these shape and annealing effects axe dominant at low excitation intensity, but do not exhibit at the high excitation intensity. The NLO refractive index of NPs shows a positive linear relationship with the excitation intensity, whereas NW and NWAs exhibit a negative linear relationship. The results could provide some foundational guidance to applications of anatase TiO2 in optoelectronic devices or other aspects.展开更多
The crystal structUre of the title ligand and its copper (Ⅱ) complex was determined bysingle crystal X-ray diffraction. The electrochendcal properties and the third-order nonlinearoptical response of the ligand and i...The crystal structUre of the title ligand and its copper (Ⅱ) complex was determined bysingle crystal X-ray diffraction. The electrochendcal properties and the third-order nonlinearoptical response of the ligand and its copper (Ⅱ) complex were also studied.展开更多
Optical responses in dilute composites are controlled through the local dielectric resonance of metallic clusters. We consider two located metallic clusters close to each other with admittances ε1 and ε2. Through va...Optical responses in dilute composites are controlled through the local dielectric resonance of metallic clusters. We consider two located metallic clusters close to each other with admittances ε1 and ε2. Through varying the difference admittance ratio η[= （ε2 - ε0）/（ε1 - ε0）], we find that their optical responses are determined by the local resonance. There is a blueshift of absorption peaks with the increase of η- Simultaneously, it is known that the absorption peaks will be redshifted by enlarging the cluster size. By adjusting the nano-metallic cluster geometry, size and admittances, we can control the positions and intensities of absorption peaks effectively. We have also deduced the effective linear optical responses of three-component composites εe=ε0 （1＋∑^n n=1[（γn1＋ηγn2）/（ε0（s-sn））]） and the sum rule of cross sections：∑^n n=1（γn1＋ηγn2）=Nh1＋Nh2,, where Nh1and Nh2 are the numbers of εl and ε2 bonds along the electric field, respectively. These results may be beneficial to the study of surface plasmon resonances on a nanometre scale.展开更多
We synthesize hollow-structured Ag@Au nanoparticles with single porous shell and Ag@Au/Ag@Au double shells by using the galvanic replacement reaction and investigate their linear and nonlinear optical properties. Our ...We synthesize hollow-structured Ag@Au nanoparticles with single porous shell and Ag@Au/Ag@Au double shells by using the galvanic replacement reaction and investigate their linear and nonlinear optical properties. Our results show that the surface plasmon resonance wavelength of the hollow porous nanoparticles could be easily tuned in a wide range in the visible and near infrared region by controlling the volume of HAuCl4. The nonlinear optical refraction of the double-shelled Ag@Au/Ag@Au nanoparticles is prominently enhanced by the plasmon resonance. Our findings may find applications in biosensors and nonlinear optical nanodevices.展开更多
With the frame of the time-dependent local density approximation, an efficient description of the optical response of clusters has been used to study the photo-absorption cross section of Na2 and Na4 clusters. It is s...With the frame of the time-dependent local density approximation, an efficient description of the optical response of clusters has been used to study the photo-absorption cross section of Na2 and Na4 clusters. It is shown that our calculated results are in good agreement with the experiment. In addition, our calculated spectrum for the Na4 cluster is in better agreement with experiment than the GW absorption spectrum.展开更多
The third-order nonlinear optical properties of water-soluble Cu Se nanocrystals are studied in the near infrared range of 700-980 nm using a femtosecond pulsed laser by the Z-scan technique. It is observed that the n...The third-order nonlinear optical properties of water-soluble Cu Se nanocrystals are studied in the near infrared range of 700-980 nm using a femtosecond pulsed laser by the Z-scan technique. It is observed that the nonlinear optical response of Cu Se nanocrystals is sensitively dependent on the excitation wavelength and exhibits the enhanced nonlinearity compared with other selenides such as ZnSe and CdSe. The W-shaped Z-scan trace, a mixture of the reversed saturated absorption and saturated absorption, is observed near the plasmon resonance band of Cu Se nanocrystals, which is attributed to the state-filling of free carriers generated by copper vacancies (self-doping effect) of Cu Se nanocrystals as well as the hot carrier thermal effect upon intense femtosecond laser excitation. The large nonlinear optical response and tunable plasmonic band make Cu Se nanocrystals promising materials for applications in ultra-fast all-optical switching devices as well as nonlinear nanosensors.展开更多
The efficiency of nanoscale nonlinear elements in photonic integrated circuits is hindered by the physical limits to the nonlinear optical response of dielectrics,which cannot be engineered as it is a fundamental mate...The efficiency of nanoscale nonlinear elements in photonic integrated circuits is hindered by the physical limits to the nonlinear optical response of dielectrics,which cannot be engineered as it is a fundamental material property.Here,we experimentally demonstrate that ultrafast optical nonlinearities in doped semiconductors can be engineered and can easily exceed those of conventional undoped dielectrics.The electron response of heavily doped semiconductors acquires in fact a hydrodynamic character that introduces nonlocal effects as well as additional nonlinear sources.Our experimental findings are supported by a comprehensive computational analysis based on the hydrodynamic model.In particular,by studying third-harmonic generation from plasmonic nanoantenna arrays made out of heavily n-doped InGaAs with increasing levels of free-carrier density,we discriminate between hydrodynamic and dielectric nonlinearities.Most importantly,we demonstrate that the maximum nonlinear efficiency as well as its spectral location can be engineered by tuning the doping level.Crucially,the maximum efficiency can be increased by almost two orders of magnitude with respect to the classical dielectric nonlinearity.Having employed the common material platform InGaAs/InP that supports integrated waveguides,our findings pave the way for future exploitation of plasmonic nonlinearities in all-semiconductor photonic integrated circuits.展开更多
Bi-doped glass fibers with controllable optical response are essential for next-generation broadband amplifiers and tunable lasers.However,achieving broad wavelength tunability and stable near-infrared(NIR)emission re...Bi-doped glass fibers with controllable optical response are essential for next-generation broadband amplifiers and tunable lasers.However,achieving broad wavelength tunability and stable near-infrared(NIR)emission remains challenging due to limited structural modification of conventional silica glasses and variability of Bi active centers(BACs).Here,we propose a cation hybridization strategy to overcome these issues,demonstrating an enhanced ultra-broadband,multi-band NIR optical response in Bi-doped photonic glasses.Alkaline earth metal ions,such as Mg^(2+)and Ba^(2+),were employed as the hybrid cations to“repair”(Mg^(2+))and“tailor”(Ba^(2+))the flexible glass network of germanate glasses,enabling precise customization of the local environment to stabilize different BACs.Impressively,this enables a tunable optical response,ranging from one main peak emission at 1142 nm to a stable multi-band emission spanning 920,1142,1265,and 1516 nm,with an emission bandwidth of 526 nm,which is distinct from conventional rare-earth ions doped glasses.Furthermore,Bi-doped hybrid germanate glass fibers were fabricated and a positive on-off gain in multiple communication bands(O+E+S+C bands)was successfully achieved.The results offer new insights into the Bi NIR luminescence behavior and introduce a promising strategy for developing advanced photonic glass materials.展开更多
Plasmonic nanostructures,particularly those composed of noble metals such as gold and silver,have garnered extensive attention due to their exceptional physical and chemical properties,which are highly advantageous fo...Plasmonic nanostructures,particularly those composed of noble metals such as gold and silver,have garnered extensive attention due to their exceptional physical and chemical properties,which are highly advantageous for optical sensing applications.The unique characteristics of DNA enable the precise spatial arrangement and functionalization of nanoparticles,allowing for the tailoring of optical characteristics within plasmonic systems.This review encompasses the development of DNA nanotechnology and its application in constructing plasmonic nanostructures featuring diverse geometric configurations.It emphasizes the tailored optical responses of these structures,including surface-enhanced Raman scattering(SERS),fluorescence enhancement,and chirality.The review concludes with a discussion of the opportunities and challenges facing DNA-based plasmonic nanostructures.展开更多
In this paper, the positive influence of a uni-traveling-carrier （UTC） structure to ease the contract between the respon- sivity and working speed of the InP-based double hetero-junction phototransistor （DHPT） is ...In this paper, the positive influence of a uni-traveling-carrier （UTC） structure to ease the contract between the respon- sivity and working speed of the InP-based double hetero-junction phototransistor （DHPT） is illustrated in detail. Different results under electrical bias, optical bias or combined electrical and optical bias are analyzed for an excellent UTC-DHPT performance. The results show that when the UTC-DHPT operates at three-terminal （3T） working mode with combined electrical bias and optical bias in base, it keeps a high optical responsivity of 34.72 A/W and the highest optical transition frequency of 120 GHz. The current gain of the 3T UTC-DHPT under 1.55-μm light illuminations reaches 62 dB. This indicates that the combined base electrical bias and optical bias of 3T UTC-DHPT can make sure that the UTC-DHPT provides high optical current gain and high optical transition frequency simultaneously.展开更多
The optical response of metal nanoparticles can be modified through near-field or far-field interaction,yet the lattice plasmon modes(LPMs)considered can only be excited from the latter.Here instead,we present a theor...The optical response of metal nanoparticles can be modified through near-field or far-field interaction,yet the lattice plasmon modes(LPMs)considered can only be excited from the latter.Here instead,we present a theoretical evaluation for LPM excitation via the near-field coupling process.The sample is an arrayed structure with specific units composed of upper metal disks,a lower metal hole and a sandwiched dielectric post.The excitation process and underlying mechanism of the LPM and the influence of the structure parameters on the optical properties have been investigated in detail by using a finite-difference time-domain(FDTD)numerical method.Our investigation presented here should advance the understanding of near-field interaction of plasmon modes for LPM excitation,and LPMs could find some potential applications,such as in near-field optical microscopes,biosensors,optical filters and plasmonic lasers.展开更多
The photonic spin Hall effect has attracted considerable research interest due to its potential applications in spincontrolled nanophotonic devices.However,realization of the asymmetrical photonic spin Hall effect wit...The photonic spin Hall effect has attracted considerable research interest due to its potential applications in spincontrolled nanophotonic devices.However,realization of the asymmetrical photonic spin Hall effect with a single optical element is still a challenge due to the conjugation of the Pancharatnam-Berry phase,which reduces the flexibility in various applications.Here,we demonstrate an asymmetrical spin-dependent beam splitter based on a single-layer dielectric metasurface exhibiting strong and controllable optical response.The metasurface consists of an array of dielectric nanofins,where both varying rotation angles and feature sizes of the unit cells are utilized to create high-efficiency dielectric metasurfaces,which enables to break the conjugated characteristic of phase gradient.Thanks to the superiority of the phase modulation ability,when the fabricated metasurface is under normal incidence with a wavelength of 1550 nm,the lefthanded circular polarization(LCP)light exhibits an anomalous refraction angle of 28.9°,while the right-handed circular polarization(RCP)light transmits directly.The method we proposed can be used for the flexible manipulation of spin photons and has potentials in high efficiency metasurfaces with versatile functionalities,especially with metasurfaces in a compact space.展开更多
The effect of replacing the anion from N to Bi down the group in the periodic table is investigated on SrMg2X2（X = N,P,As,Sb,Bi）.A full potential linearized augmented plane wave plus local orbitals method is used al...The effect of replacing the anion from N to Bi down the group in the periodic table is investigated on SrMg2X2（X = N,P,As,Sb,Bi）.A full potential linearized augmented plane wave plus local orbitals method is used along with different exchange–correlation potentials to obtain the lattice constants,phonons,electronic,and optical properties of the Sr Mg2X2（X = N,P,As,Sb,Bi） Zintl compounds.A good agreement is achieved and our calculations are validated by previous experimental and theoretical data.All compounds have shown stable dynamical behavior with gamma centered longitudinal response having no imaginary frequencies.Electronic band structures reveal the semiconducting nature of the compounds.The Pnictogen（X）-p state contributed mainly in the valence band and the Sr-d state forms the conduction of the compounds.Relative charge transfer and low overlapping of the atomic densities indicates the preferable ionic bonding character of these materials.In the optical properties,real and imaginary parts of dielectric function,complex refractive index,birefringence,reflectivity,and optical conductivity are calculated.These compounds can be utilized in the optical and optoelectronic devices.展开更多
基金Project supported by the National Key R&D Program of China (Grant Nos.2018YFA, 0305601, and 2021YFA1400100)the National Natural Science Foundation of China (Grant Nos.12274003, 11725415, and 11934001)the Innovation Program for Quantum Science and Technology (Grant No.2021ZD0302600)。
文摘A Weyl node is characterized by its chirality and tilt.We develop a theory of how nth-order nonlinear optical conductivity behaves under transformations of anisotropic tensor and tilt, which clarifies how chirality-dependent and-independent parts of optical conductivity transform under the reversal of tilt and chirality.Built on this theory, we propose ferromagnetic Mn Bi2Te4as a magnetoelectrically regulated, terahertz optical device, by magnetoelectrically switching the chiralitydependent and-independent DC photocurrents.These results are useful for creating nonlinear optical devices based on the topological Weyl semimetals.
基金supported by National Natural Science Foundation of China(Grant Nos.12025407,12474246,and 12450401)the National Key Research and Development Program of China(Grant No.2021YFA1400201)the Chinese Academy of Sciences(Grant Nos.YSBR-047 and XDB33030100)。
文摘The quantum metric manifested as the Riemannian metric in the parameter space of Bloch bands,characterizes the topology and geometry of quantum states.The second harmonic generation(SHG),as one of the fundamental nonlinear optical responses that links geometry of optical transitions to physical observables,despite being widely studied in various materials,its relation to quantum metric,especially in the dynamical regime,stays obscure.
文摘Bulk materials were synthesized by the Bridgman technique using the elements Cu, Ga, Se. These samples were characterized by Energy Dispersive Spectrometry (EDS) to determine the elemental composition, as well as by X-ray diffraction for structure, hot point probe method for type of conductivity. Optical response (Photoconductivity) and Photoluminescence (PL) and PL-excitation (PLE) at temperatures from 4.2 to 77 K were also used to estimate the band-gap energy of Cu-Ga<sub>3</sub>Se<sub>5</sub>. They show a nearly perfect stoechiometry and present p-type conductivity. CuGa<sub>3</sub>Se<sub>5</sub> either have an Ordered Defect Chalcopyrite structure (ODC), or an Ordered Vacancy Chalcopyrite structure (OVC). The gap energy obtained by Photoconductivity and Photoluminescence (PL) for the different samples is 1.85 eV. Studying the variation of the gap as a function of the temperature shows that the transition is a D-A type. The defects that appear are probably Ga<sub>Cu</sub>.
基金financially supported by the National Natural Science Foundation of China(Nos.20804027 and 21274106)Shanghai Key Laboratory of Magnetic Resonance
文摘Optically active and inactive hyperbranched polymers with specific thermoresponsive behaviours in water were reported.Through two steps hyperbranched polyethylenimine（HPEI） polymers terminated with different amount of D-phenylalanine（D-Phe）,L-phenylalanine（L-Phe） or DL-phenylalanine（DL-Phe） were prepared and characterized.The analyses on the solution properties by turbidimetry,dynamic light scattering,fluorescence probe and 1H-NMR demonstrated that all the polymers exhibited specific thermoresponsive behaviours in water,including：（1） In the dilute polymer concentration region,increasing the polymer concentration led to the increase of phase transition temperature;（2） The optically inactive thermoresponsive hyperbranched polymers showed a higher cloud-point temperature（Tcp） than their corresponding optically active ones in a relatively higher polymer concentration;（3） At the same polymer concentration the hydrophobic groups of the optically inactive HPEI-DL-Phe formed more perfect hydrophobic domain than those of the optically active HPEI-L-Phe and HPEI-D-Phe.
文摘Dear Editor,Multiple evanescent white dot syndrome （MEWDS） was first described in 1984 as a rare, acute, unilateral,multifocal retinochoroidal disorder, typically affecting young myopic women. Previous studies with fluorescein angiography （FA） and electrophysiology suggested that MEWDS to be a disease in the retinal pigment epithelium （RPE） or outer retina, while recent studies with spectral- domain optical coherence tomography （SD-OCT） suggested it may be an outer retinal disease due to observation of hyperreflective material in outer retina and subtle disruptionsof the ellipsoid zone without RPE disruption.
基金the National Key R&D Program of China(Grant No.2017YFA0303600)the National Natural Science Foundation of China(Grant No.11974253)Science Speciality Program of Sichuan University(Grant No.2020SCUNL210)。
文摘Graphite carbon nitride(g-C_(3)N_(4))attracts wide-ranging research interest due to its extraordinary physicochemical properties and promising applications ranging from heterogeneous catalysis to fuel cells.In this work,we design different g-C_(3)N_(4)-based quantum dots(g CNQDs),carry out a systematic study of optical properties,and elucidate the shape selectivity,composite nanostructure,and outfield effect.In particular,composites of g CNQDs and metal nanochains present excellent optical response,making it applicable to bioimaging,nano-plasma devices,and metalloenzyme in infrared light related fields.Besides,QDs which original bridging nitrogen atoms are replaced by amino(–NH_(2)),hydroxyl(–OH),and methyl(–CH_(3))functional groups respectively,have excellent spectral selectivity in the deep ultraviolet region.More interestingly,in the study of the laser interaction with materials,the g CNQDs exhibit extremely high stability and light corrosion resistance.Phase transition from insulation to metal is observed under the critical condition of about 5 e V intensity or 337 nm wavelength.All provided theoretical support for designs and applications in g-C_(3)N_(4)quantum devices.
基金Universidad de Medellín for hospitality and support during their 2019–2020 sabbatical stayMexican CONACYT through research Grant A1-S-8218。
文摘We present a theoretical study on the effects of intense laser field(ILF)and static electric field on the linear and nonlinear optical properties of a cylindrical quantum dot with Rosen-Morse axial potential under the framework of effective mass and parabolic band approximations.This study also takes into account the effects of the structure parameters(η,V1,and R).The analytical expressions of the linear,third-order nonlinear and total optical absorption coefficients(TOACs)and the relative refractive index changes(RRICs)are obtained by using the compact-densitymatrix approach.The results of numerical calculations show that the resonant peak position of the TOACs and RRICs shifts towards lower energies and the magnitude of the peak increases with the effect of the static electric field and ILF.In addition,it is observed that while the resonant energies of the TOACs and RRICs of system shift towards the higher(lower)energies with the enhancement ofη,V1,they decrease with the augmentation of R.Thus,the findings of this study show that the optical properties of the structure can be adjusted by changing the magnitude of structure parameters and applied external fields.
基金Supported by the National Natural Science Foundation of China under Grant Nos 11404410 and 11504105
文摘Nonlinear optical （NLO） properties of anatase TiO2 with nanostructures of nanopaxticle （NP）, nanowire （NW） and annealed nanowire （NWA） are studied by open-aperture and closed-aperture Z-scan techniques with a fem- tosecond pulsed laser at wavelengths of 532 nm and 780 nm simultaneously. At 532 nm, when increasing excitation intensity, NLO absorption of TiO2 NPs transforms from saturable absorption to reverse-saturable absorption. However, NWs and NWAs exhibit the opposite change. At 780nm, all samples show reverse-saturable absorption, but have different sensitivities to excitation intensity. Due to the larger surface-to-volume ratio of NPs and less defects of NWAs by annealing, nonlinear optical absorption coet^icients follow the order NPs≥ NWs≥ NWAs. The results also show that these shape and annealing effects axe dominant at low excitation intensity, but do not exhibit at the high excitation intensity. The NLO refractive index of NPs shows a positive linear relationship with the excitation intensity, whereas NW and NWAs exhibit a negative linear relationship. The results could provide some foundational guidance to applications of anatase TiO2 in optoelectronic devices or other aspects.
文摘The crystal structUre of the title ligand and its copper (Ⅱ) complex was determined bysingle crystal X-ray diffraction. The electrochendcal properties and the third-order nonlinearoptical response of the ligand and its copper (Ⅱ) complex were also studied.
基金Project supported by the National Natural Science Foundation of China（Grant Nos 10304001, 10334010, 10521002, 10434020, 10328407 and 90501007）.
文摘Optical responses in dilute composites are controlled through the local dielectric resonance of metallic clusters. We consider two located metallic clusters close to each other with admittances ε1 and ε2. Through varying the difference admittance ratio η[= （ε2 - ε0）/（ε1 - ε0）], we find that their optical responses are determined by the local resonance. There is a blueshift of absorption peaks with the increase of η- Simultaneously, it is known that the absorption peaks will be redshifted by enlarging the cluster size. By adjusting the nano-metallic cluster geometry, size and admittances, we can control the positions and intensities of absorption peaks effectively. We have also deduced the effective linear optical responses of three-component composites εe=ε0 （1＋∑^n n=1[（γn1＋ηγn2）/（ε0（s-sn））]） and the sum rule of cross sections：∑^n n=1（γn1＋ηγn2）=Nh1＋Nh2,, where Nh1and Nh2 are the numbers of εl and ε2 bonds along the electric field, respectively. These results may be beneficial to the study of surface plasmon resonances on a nanometre scale.
基金Supported by the National Natural Science Foundation of China under Grant Nos 11174229,11204221 and 11374236the National Basic Research Program of China under Grant No 2011CB922201
文摘We synthesize hollow-structured Ag@Au nanoparticles with single porous shell and Ag@Au/Ag@Au double shells by using the galvanic replacement reaction and investigate their linear and nonlinear optical properties. Our results show that the surface plasmon resonance wavelength of the hollow porous nanoparticles could be easily tuned in a wide range in the visible and near infrared region by controlling the volume of HAuCl4. The nonlinear optical refraction of the double-shelled Ag@Au/Ag@Au nanoparticles is prominently enhanced by the plasmon resonance. Our findings may find applications in biosensors and nonlinear optical nanodevices.
基金The project supported by National Natural Science Foundation of China under Grant Nos. 10405025, 10575012, 10435020, and 10535010
文摘With the frame of the time-dependent local density approximation, an efficient description of the optical response of clusters has been used to study the photo-absorption cross section of Na2 and Na4 clusters. It is shown that our calculated results are in good agreement with the experiment. In addition, our calculated spectrum for the Na4 cluster is in better agreement with experiment than the GW absorption spectrum.
基金Supported by the National Natural Science Foundation of China under Grant Nos 11274302,11474276 and 11674240
文摘The third-order nonlinear optical properties of water-soluble Cu Se nanocrystals are studied in the near infrared range of 700-980 nm using a femtosecond pulsed laser by the Z-scan technique. It is observed that the nonlinear optical response of Cu Se nanocrystals is sensitively dependent on the excitation wavelength and exhibits the enhanced nonlinearity compared with other selenides such as ZnSe and CdSe. The W-shaped Z-scan trace, a mixture of the reversed saturated absorption and saturated absorption, is observed near the plasmon resonance band of Cu Se nanocrystals, which is attributed to the state-filling of free carriers generated by copper vacancies (self-doping effect) of Cu Se nanocrystals as well as the hot carrier thermal effect upon intense femtosecond laser excitation. The large nonlinear optical response and tunable plasmonic band make Cu Se nanocrystals promising materials for applications in ultra-fast all-optical switching devices as well as nonlinear nanosensors.
文摘The efficiency of nanoscale nonlinear elements in photonic integrated circuits is hindered by the physical limits to the nonlinear optical response of dielectrics,which cannot be engineered as it is a fundamental material property.Here,we experimentally demonstrate that ultrafast optical nonlinearities in doped semiconductors can be engineered and can easily exceed those of conventional undoped dielectrics.The electron response of heavily doped semiconductors acquires in fact a hydrodynamic character that introduces nonlocal effects as well as additional nonlinear sources.Our experimental findings are supported by a comprehensive computational analysis based on the hydrodynamic model.In particular,by studying third-harmonic generation from plasmonic nanoantenna arrays made out of heavily n-doped InGaAs with increasing levels of free-carrier density,we discriminate between hydrodynamic and dielectric nonlinearities.Most importantly,we demonstrate that the maximum nonlinear efficiency as well as its spectral location can be engineered by tuning the doping level.Crucially,the maximum efficiency can be increased by almost two orders of magnitude with respect to the classical dielectric nonlinearity.Having employed the common material platform InGaAs/InP that supports integrated waveguides,our findings pave the way for future exploitation of plasmonic nonlinearities in all-semiconductor photonic integrated circuits.
基金supported by the National Natural Science Foundation of China(62405092,62122027,62075063,62205109)the Postdoctoral Fellowship Program of China Postdoctoral Science Foundation(GZC20230852)the Guangdong Basic and Applied Basic Research Foundation(2025A1515010444).
文摘Bi-doped glass fibers with controllable optical response are essential for next-generation broadband amplifiers and tunable lasers.However,achieving broad wavelength tunability and stable near-infrared(NIR)emission remains challenging due to limited structural modification of conventional silica glasses and variability of Bi active centers(BACs).Here,we propose a cation hybridization strategy to overcome these issues,demonstrating an enhanced ultra-broadband,multi-band NIR optical response in Bi-doped photonic glasses.Alkaline earth metal ions,such as Mg^(2+)and Ba^(2+),were employed as the hybrid cations to“repair”(Mg^(2+))and“tailor”(Ba^(2+))the flexible glass network of germanate glasses,enabling precise customization of the local environment to stabilize different BACs.Impressively,this enables a tunable optical response,ranging from one main peak emission at 1142 nm to a stable multi-band emission spanning 920,1142,1265,and 1516 nm,with an emission bandwidth of 526 nm,which is distinct from conventional rare-earth ions doped glasses.Furthermore,Bi-doped hybrid germanate glass fibers were fabricated and a positive on-off gain in multiple communication bands(O+E+S+C bands)was successfully achieved.The results offer new insights into the Bi NIR luminescence behavior and introduce a promising strategy for developing advanced photonic glass materials.
基金supported by the National Natural Science Foundation of China(Nos.22274081,62288102,and 62401494)the Natural Science Foundation of Jiangsu Province(No.BE2023839).
文摘Plasmonic nanostructures,particularly those composed of noble metals such as gold and silver,have garnered extensive attention due to their exceptional physical and chemical properties,which are highly advantageous for optical sensing applications.The unique characteristics of DNA enable the precise spatial arrangement and functionalization of nanoparticles,allowing for the tailoring of optical characteristics within plasmonic systems.This review encompasses the development of DNA nanotechnology and its application in constructing plasmonic nanostructures featuring diverse geometric configurations.It emphasizes the tailored optical responses of these structures,including surface-enhanced Raman scattering(SERS),fluorescence enhancement,and chirality.The review concludes with a discussion of the opportunities and challenges facing DNA-based plasmonic nanostructures.
基金Project supported by the National Natural Science Foundation of China(Grant No.61006044)the Natural Science Foundation of Beijing,China(Grant Nos.4122014 and 4142007)the Fund from the Beijing Municipal Education Committee,China(Grant No.KM200910005001)
文摘In this paper, the positive influence of a uni-traveling-carrier （UTC） structure to ease the contract between the respon- sivity and working speed of the InP-based double hetero-junction phototransistor （DHPT） is illustrated in detail. Different results under electrical bias, optical bias or combined electrical and optical bias are analyzed for an excellent UTC-DHPT performance. The results show that when the UTC-DHPT operates at three-terminal （3T） working mode with combined electrical bias and optical bias in base, it keeps a high optical responsivity of 34.72 A/W and the highest optical transition frequency of 120 GHz. The current gain of the 3T UTC-DHPT under 1.55-μm light illuminations reaches 62 dB. This indicates that the combined base electrical bias and optical bias of 3T UTC-DHPT can make sure that the UTC-DHPT provides high optical current gain and high optical transition frequency simultaneously.
基金Key Laboratory of Energy Conversion and Storage Technologies(Southern University of Science and Technology),Ministry of Education,Shenzhen,China,the National Key Research and Development Program of China(Grant No.2018YFB0406702)Professorship Startup Funding(Grant No.217056)+1 种基金Innovation-Driven Project of Central South University(Grant No.2018CX001)Project of State Key Laboratory of High Performance Complex Manufacturing,Central South University(Grant No.ZZYJKT2018-01).
文摘The optical response of metal nanoparticles can be modified through near-field or far-field interaction,yet the lattice plasmon modes(LPMs)considered can only be excited from the latter.Here instead,we present a theoretical evaluation for LPM excitation via the near-field coupling process.The sample is an arrayed structure with specific units composed of upper metal disks,a lower metal hole and a sandwiched dielectric post.The excitation process and underlying mechanism of the LPM and the influence of the structure parameters on the optical properties have been investigated in detail by using a finite-difference time-domain(FDTD)numerical method.Our investigation presented here should advance the understanding of near-field interaction of plasmon modes for LPM excitation,and LPMs could find some potential applications,such as in near-field optical microscopes,biosensors,optical filters and plasmonic lasers.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.12074420,U21A20140,and 61905274)the Beijing Municipal Science&Technology Commission,Administrative Commission of Zhongguancun Science Park(Grant No.Z211100004821009)+1 种基金the Chinese Academy of Sciences through the Project for Young Scientists in Basic Research(Grant No.YSBR-021)the Synergic Extreme Condition User Facility
文摘The photonic spin Hall effect has attracted considerable research interest due to its potential applications in spincontrolled nanophotonic devices.However,realization of the asymmetrical photonic spin Hall effect with a single optical element is still a challenge due to the conjugation of the Pancharatnam-Berry phase,which reduces the flexibility in various applications.Here,we demonstrate an asymmetrical spin-dependent beam splitter based on a single-layer dielectric metasurface exhibiting strong and controllable optical response.The metasurface consists of an array of dielectric nanofins,where both varying rotation angles and feature sizes of the unit cells are utilized to create high-efficiency dielectric metasurfaces,which enables to break the conjugated characteristic of phase gradient.Thanks to the superiority of the phase modulation ability,when the fabricated metasurface is under normal incidence with a wavelength of 1550 nm,the lefthanded circular polarization(LCP)light exhibits an anomalous refraction angle of 28.9°,while the right-handed circular polarization(RCP)light transmits directly.The method we proposed can be used for the flexible manipulation of spin photons and has potentials in high efficiency metasurfaces with versatile functionalities,especially with metasurfaces in a compact space.
基金Project supported by a grant from the"Research Center of Female Scientific and Medical Colleges",the Deanship of Scientific Research,King Saud UniversityYaseen M is thankful to Higher Education Commission(HEC)+1 种基金Pakistan for funding(Grant No.6410/Punjab/NRPU/R&D/HEC/2016)the support of the United States Government and the American people through the United States Agency for International Development(USAID)
文摘The effect of replacing the anion from N to Bi down the group in the periodic table is investigated on SrMg2X2（X = N,P,As,Sb,Bi）.A full potential linearized augmented plane wave plus local orbitals method is used along with different exchange–correlation potentials to obtain the lattice constants,phonons,electronic,and optical properties of the Sr Mg2X2（X = N,P,As,Sb,Bi） Zintl compounds.A good agreement is achieved and our calculations are validated by previous experimental and theoretical data.All compounds have shown stable dynamical behavior with gamma centered longitudinal response having no imaginary frequencies.Electronic band structures reveal the semiconducting nature of the compounds.The Pnictogen（X）-p state contributed mainly in the valence band and the Sr-d state forms the conduction of the compounds.Relative charge transfer and low overlapping of the atomic densities indicates the preferable ionic bonding character of these materials.In the optical properties,real and imaginary parts of dielectric function,complex refractive index,birefringence,reflectivity,and optical conductivity are calculated.These compounds can be utilized in the optical and optoelectronic devices.
