Perovskite nanocrystals(NCs) with high two-photon absorption(TPA) cross-section are of great interest due to their potential applications in three-dimensional optical data storage and multiphoton fluorescence microsco...Perovskite nanocrystals(NCs) with high two-photon absorption(TPA) cross-section are of great interest due to their potential applications in three-dimensional optical data storage and multiphoton fluorescence microscopy. Among various perovskite materials, FAPbBr_(3) NCs show a better development prospect due to their excellent stability. However, there are few reports on their nonlinear optical properties. In this work, the nonlinear optical behavior of FAPbBr_(3) NCs is studied.The methods of multiphoton absorption photoluminescence saturation and open aperture Z-scan technique were applied to determine the TPA cross-section of FAPbBr_(3)NCs, which was around 2.76 × 10^(-45)cm^(4)·s·photon^(-1) at 800 nm. In addition,temperature-dependent photoluminescence induced by TPA was investigated, and the small longitudinal optical phonon energy and electron–phonon coupling strength was obtained, which confirm the weak Pb–Br interaction. Meanwhile, it is found that the exciton binding energy in FAPbBr_(3) NCs was 69.668 me V, which may be ascribed to the strong hydrogen bond interaction. It is expected that our findings will promote the application of FAPbBr_(3) NCs in optoelectronic devices.展开更多
Soliton dynamics are numerically investigated in a two-mode fiber with the two-photon absorption,and the effects of the two-photon absorption on the soliton propagation and interaction are demonstrated in different di...Soliton dynamics are numerically investigated in a two-mode fiber with the two-photon absorption,and the effects of the two-photon absorption on the soliton propagation and interaction are demonstrated in different dispersion regimes.Soliton dynamics depend strictly on the sign and magnitude of the group velocity dispersion(GVD)coefficient of each mode and the strength(coefficient)of the two-photon absorption.The two-photon absorption leads to the soliton collapse,enhances the neighboring soliton interaction in both modes,and increases the energy exchange between the two modes.Finally,an available control is proposed to suppress the effects by the use of the nonlinear gain with filter.展开更多
Improving the up-conversion luminescence efficiency of rare-earth ions via the multi-photon absorption process is crucial in several related application areas. In this work, we theoretically propose a feasible scheme ...Improving the up-conversion luminescence efficiency of rare-earth ions via the multi-photon absorption process is crucial in several related application areas. In this work, we theoretically propose a feasible scheme to enhance the resonance-mediated two-photon absorption in Er^(3+) ions by shaping the femtosecond laser field with a rectangle phase modulation. Our theoretical results show that the resonance-mediated two-photon absorption can be decomposed into the on-resonant and near-resonant parts, and the on-resonant part mainly comes from the contribution of laser central frequency components, while the near-resonant part mainly results from the excitation of low and high laser frequency components.So, the rectangle phase modulation can induce a constructive interference between the two parts by properly designing the modulation depth and width, and finally realizes the resonance-mediated two-photon absorption enhancement. Moreover, our results also show that the enhancement efficiency of resonance-mediated two-photon absorption depends on the laser pulse width(or laser spectral bandwidth), final state transition frequency, and intermediate and final state absorption bandwidths. The enhancement efficiency modulation can be attributed to the relative weight manipulation of on-resonant and near-resonant two-photon absorption in the whole excitation process. This study presents a clear physical insight for the quantum control of resonance-mediated two-photon absorption in the rare-earth ions, and there will be an important significance for improving the up-conversion luminescence efficiency of rare-earthions.展开更多
A series of novel organic compounds named as CSPI, DPASPI, PSPI DEASPI and HEASPI respectively, with large two-photon absorption has been synthesized and their structures have been determined by 1HNMR and elemental an...A series of novel organic compounds named as CSPI, DPASPI, PSPI DEASPI and HEASPI respectively, with large two-photon absorption has been synthesized and their structures have been determined by 1HNMR and elemental analysis. The highest two-photon pumped (TPP) output /input efficiency is as high as 13.4% for PSPI in DMF with d0 = 0.03 mol/L and the effective two-photon absorption cross section is 8.8(10-48 cm4(s/photon for DPASPI in DMF with d0= 0.05mol/L.展开更多
In this work,a neural network(NN)method is developed for pulse duration inferring for an erbium-doped fiber laser at 1550 nm.Experime nt ally,the interferometric autocorrelation trace is observed clearly with the use ...In this work,a neural network(NN)method is developed for pulse duration inferring for an erbium-doped fiber laser at 1550 nm.Experime nt ally,the interferometric autocorrelation trace is observed clearly with the use of the two-photon absorption(TPA)effect in a GaAs photodiode.The intensity autocorrelation function is curvefitted by the NN with an appropriate performance,and the measuring accuracy is consistent with a commercial autocorrelator.Compared with the Levenberg-Marquardt curve-fitting method,the NN can retrieve the intensity autocorrelation function more stably and has a certain noise reduction ability,simplifying the signal processing for a TPA photodiode-based autocorrelator.展开更多
The properties of one-photon absorption(OPA),emission and two-photon absorption(TPA)of a bipyridine-based zinc ion probe are investigated employing the density functional theory in combination with response functions....The properties of one-photon absorption(OPA),emission and two-photon absorption(TPA)of a bipyridine-based zinc ion probe are investigated employing the density functional theory in combination with response functions.The responsive mechanism and coordination mode effect are explored.The structural fluctuation is illustrated by molecular dynamics simulation.The calculated OPA and emission wavelengths of the probe are consistent with the experimental data.It is found that the red-shift of OPA wavelength and the enhancement of TPA intensity are induced by the increased intra-molecular charge transfer mechanism upon metal binding.The structural fluctuation could result in the blue-shift of TPA wavelength and the decrease of the TPA cross section.The TPA properties are quite different among the zinc complexes with different coordination modes.The TPA wavelength of the complexes with two ligands is close to that of the probe,which is in agreement with the experimental observation.展开更多
Cuprous oxide(Cu_(2)O)has attracted plenty of attention for potential nonlinear photonic applications due to its superior third-order nonlinear optical property such as two-photon absorption.In this paper,we investiga...Cuprous oxide(Cu_(2)O)has attracted plenty of attention for potential nonlinear photonic applications due to its superior third-order nonlinear optical property such as two-photon absorption.In this paper,we investigated the two-photon excitation induced carrier dynamics of a Cu_(2)O thin film prepared by radio-frequency magnetron sputtering,using the femtosecond transient absorption experiments.Biexponential dynamics including an ultrafast carrier scattering(<1 ps)followed by a carrier recombination(>50 ps)were observed.The time constant of carrier scattering under two-photon excitation is larger than that under one-photon excitation,due to the different transition selection rules and smaller absorption coefficient of the two-photon excitation.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
To improve two-photon absorption(TPA)response of a newly synthesized probe,a series of ratiometric two-photon fluorescent Zn^(2+) sensors based on quinoline and DPA moieties have been designed.The one-photon absorptio...To improve two-photon absorption(TPA)response of a newly synthesized probe,a series of ratiometric two-photon fluorescent Zn^(2+) sensors based on quinoline and DPA moieties have been designed.The one-photon absorption,TPA,and emission properties of the experimental and designed probes before and after coordination with Zn^(2+) are investigated employing the density functional theory in combination with response functions.The design consists of two levels.In the first level of design,five probes are constructed through using several electron acceptors or donors to increase accepting or donating ability of the fluorophores.It shows that all the designed probes have stronger TPA intensities at longer wavelengths with respect to the experimental probe because of the increased intra-molecular charge transfer.Moreover,it is found that the probe 4 built by adding an acyl unit has the largest TPA cross section among the designed structures due to the form of longer conjugated length and more linear backbone.One dimethylamino terminal attached along the skeleton can improve TPA intensity more efficiently than two side amino groups.Therefore,in the second level of design,a new probe 7 is formed by both an acyl unit and a dimethylamino terminal.It exhibits that the TPA cross sections of probe 7 and its zinc complex increase dramatically.Furthermore,the fluorescence quantum yields of the designed probes4 and 7 are calculated in a new way,which makes use of the relation between the computed difference of dipole moment and the measured fluorescence quantum yield.The result shows that our design also improves the fluorescence quantum yield considerably.All in all,the designed probes 4 and 7 not only possess enhanced TPA intensities but also have large differences of emission wavelength upon Zn^(2+) coordination and strong fluorescence intensity,which demonstrates that they are potential ratiometric two-photon fluorescent probes.展开更多
Partial genetically encoded 4-hy-droxybenzylidene-imidazolinone(HBI)-type chromophores are new promising fluorescent probes,which are suitable for imaging and detection of living cells.How-ever,the lack of infrared ch...Partial genetically encoded 4-hy-droxybenzylidene-imidazolinone(HBI)-type chromophores are new promising fluorescent probes,which are suitable for imaging and detection of living cells.How-ever,the lack of infrared chro-mophores hinders the develop-ment seriously.Here more than 30 HBI-type chromophores with reg-ular structure modifications were employed and typical spectral redshift change laws and mechanisms were investigated by quantum methods.Results show that both one-photon spectrum(OPS,absorption/emission)and two-photon absorption(TPA)can achieve large redshift via either extending conjugated lengths of frag-3 or enlarging conjugated areas of frag-1 of HBI skeleton.Spectral redshifts of all chromophores are highly related to intramolecular charge transfer(ICT),but neutral ones are closely related to the total ICT or electron-accept-ing-numbers of frag-3,and the high correlative factor of anions is the aromaticity of frag-2 bridge.The frag-2 bridge with high aromaticity can open a reverse charge transfer channel in anion relative to neutral,obtaining significant redshift.Based on analysis,a new 6-hydroxyl-naphthalene-imidazolinone(HNI)series,which have larger conjugated area in frag-1,are pre-dicted.The OPS and TPA of anionic HNI ones acquire about 76−96 nm and 119−146 nm red-shift relative to traditional HBI series respectively as a whole.The longest emission of anionic HNI-4 realizes more 244 nm redshift relative to HBI-1.Our work clarifies worthy spectral reg-ularities and redshift mechanisms of HBI-type chromophores and provides valuable design strategy for infrared chromophores synthesis in experiment.展开更多
It is firmly demonstrated in experiment that the self-absorption(SA) effect can lead to the extinction of the zero-phonon line and the first-order longitudinal optical phonon sideband of free excitonic luminescence of...It is firmly demonstrated in experiment that the self-absorption(SA) effect can lead to the extinction of the zero-phonon line and the first-order longitudinal optical phonon sideband of free excitonic luminescence of ZnO at room temperature. Moreover, effectiveness degree of SA effect is found to be dependent on both absorption coefficient and travelling distance of emitted photons, as well as even lattice temperature, which is uniquely reflected by the redshift amount in emission peak in ZnO. It is also unambiguously proved that the SA effect still strictly obeys the Beer-Lambert law of absorption. This work not only uncovers the long-term puzzle of significant redshift of emission peak of ZnO at higher temperatures, but also shows that the SA effect may have to be carefully taken into consideration in the study of spontaneous emission, laser and relevant optoelectronic processes in luminescent materials and optoelectronic devices.展开更多
The two-photon absorption induced lasing spectrum shows that the synthesized ASPBPh4, trans-4- [p- (N-methyl-N- (hydroxyethyl)amino) styryl]-N-methylpyridinium, has a distinct ef- ficiency of laser frequency up-conver...The two-photon absorption induced lasing spectrum shows that the synthesized ASPBPh4, trans-4- [p- (N-methyl-N- (hydroxyethyl)amino) styryl]-N-methylpyridinium, has a distinct ef- ficiency of laser frequency up-conversion. This nonlinear optical property of such a kind of com- pounds is related to two-photon absorption (TPA). In our work, we used the intermediate ne- glect of differential overlap (INDO) plus single-excitation configuration interaction (SCI) method to get the basic properties of the molecule, and calculated the second hyperpolarizability and the cross section of two-photon absorption by means of sum-over-state (SOS) expression. The rela- tionship between the structure and the properties is discussed.展开更多
Two triphenylamine-based star-type push-pull chromophores(T1, T2) were designed and synthesized.Triphenylamine serves as the central core and acts as an electron-donating group surrounded by electronwithdrawing pentaf...Two triphenylamine-based star-type push-pull chromophores(T1, T2) were designed and synthesized.Triphenylamine serves as the central core and acts as an electron-donating group surrounded by electronwithdrawing pentafluorobenzene or N,N-dimethyl substituted tetrafluorobenzene, which are connected by ethylene bridges. Single-crystal X-ray diffraction confirmed the structures and molecular arrangement of two chromophores. The systematic photophysical research of T1 and T2 absorption characteristics was carried out to gain a better understanding of how structure-property relationships affect the observed nonlinear optical absorption phenomenon. Complementary calculations based on density functional theory(DFT) further confirmed the experimental results. Both chromophores exhibited excellent two-photon absorption(TPA) properties in CH_(2)Cl_(2). Notably, T2 has more remarkable nonlinear optical absorption effects with the TPA cross-section up to 4.24 × 10~7GM. By adjusting the electronic structures of the chromophores through introducing pentafluorobenzene or N,N-dimethyl as functional groups with different electron-donating or withdrawing behaviors, the TPA performance of the small organic molecule could be greatly enhanced. These molecular structures with push-pull systems were excellent candidates for different two-photon applications.展开更多
Mitochondria and lysosomes are essential cellular organelles in most eukaryotic cells by playing the physiological roles to support the normal functions of cells, as well as the life of the whole body. To date,small-m...Mitochondria and lysosomes are essential cellular organelles in most eukaryotic cells by playing the physiological roles to support the normal functions of cells, as well as the life of the whole body. To date,small-molecule fluorescent probes have been considered as one of the vital tools for monitoring and visualizing multiple biological analytes. This review summarized the recent advances in small-molecule two-photon fluorescent probes for metal ions, reactive oxygen species(ROS) and reactive sulfur species(RSS), and changes inside micro-environment(e.g., p H, viscosity and polarity) in mitochondria and lysosomes, or served as mitotracker and lysotracker with the assistance of two-photon microscopy.展开更多
Two-photon excitation microscopy(2 PEM) has been known as a noninvasive and powerful bio-imaging tool for studying living cells, intact tissues and living animals because of their unique advantages such as localized e...Two-photon excitation microscopy(2 PEM) has been known as a noninvasive and powerful bio-imaging tool for studying living cells, intact tissues and living animals because of their unique advantages such as localized excitation, deep tissue penetration as well as less photo-damage. However, the major limitations that hinder its practical applications in biological systems are low two-photon absorption cross sections of conventional fluorescence probes. Conjugated polymer nanoparticles(CPNs) consisting of highly fluorescent conjugated polymers are promising fluorescent probes for 2 PEM due to their unique advantages including large two-photon absorption cross sections, high fluorescence quantum yield, good photo-stability and biocompatibility, facile chemical synthesis, tunable optical properties as well as versatile surface modifications. This account summarizes the recent efforts of our group on development of novel polyfluorene based CPNs as 2 PEM contrast agents for live cell imaging.展开更多
Since the first realization of two-photon direct laser writing(DLW)in Maruo et al.(Opt Lett 22:132-134,1997),the manufacturing using direct laser writing techniques spread out in many laboratories all over the world.P...Since the first realization of two-photon direct laser writing(DLW)in Maruo et al.(Opt Lett 22:132-134,1997),the manufacturing using direct laser writing techniques spread out in many laboratories all over the world.Photosensitive materials with different material properties open a new field for micro-and nanofabrication.The achievable structuring resolution using this technique is reported to be sub-100 nm(Paz et al.in J.Laser Appl.24:042004,2012),while a smallest linewidth of 25 nm could be shown in Tan et al.(Appl Phys Lett 90:071106,2007).In our approach,the combination of DLW with the nanopositioning and nanomeasuring machine NMM-1 offers an improvement of the technique from the engineering side regarding the ultra-precise positioning(Weidenfeller et al.in Adv Fabr Technol Micro/Nano Opt Photon Ⅺ 10544:105440E,2018).One big benefit besides the high positioning resolution of 0.1 nm is offered by the positioning range of 25 mm×25 mm×5 mm(Jager et al.in Technisches Messen 67:319-323,2000;Manske et al.in Meas Sci Technol 18:520-527,2007).Thus,a trans-scale fabrication without any stitching or combination of different positioning systems is necessary.The immense synergy between the highly precise positioning and the DLW is demonstrated by the realization of resist lines and trenches whose center-to-center distance undergoes the modified diffraction limit for two-photon processes.The precise positioning accuracy enables a defined distance between illuminated lines.Hence,with a comparable huge width of the trenches of 1.655|im due to a low effective numerical aperture of 0.16,a resist line of 30 nm between two written trenches could be achieved.Although the interrelationships for achieving such narrow trenches have not yet been clarified,much smaller resist lines and trench widths are possible with this approach in the near future.展开更多
We demonstrate a bottom-up approach to fabricating a visible light-driven titania photocatalyst device bearing an embeddedtwo-dimensional (2D) array of gold nanoparticles (AuNPs) as a near-field light-generating layer...We demonstrate a bottom-up approach to fabricating a visible light-driven titania photocatalyst device bearing an embeddedtwo-dimensional (2D) array of gold nanoparticles (AuNPs) as a near-field light-generating layer. The device is a layered structureprepared by depositing a 2D array of AuNPs on a transparent conductive substrate (10 nm indium tin oxide (ITO) layer on quartz),coating the 2D array of AuNPs with a monolayer of trimethoxyoctylsilane (TMOS), and depositing titania nanocrystals on the anchoringmolecule (TMOS) layer. The visible light activity of the device was tested using photocatalytic degradation of methylene blue (MB) byilluminating the device with visible light (700 nm light) and ultraviolet (UV) light (250–380 nm). The localized surface plasmonresonance peak of the 36 nm AuNP 2D array is around 700 nm with a full-width at half-maximum of 350 nm. In comparison with othercontrol samples, the device showed the highest photocatalytic activity with visible irradiation, which was 1.7 times higher than that oftitania with UV irradiation. The origin of the visible light activity was confirmed by both quadratic incident light power dependency andaction spectrum to be plasmon-induced (near-field enhancement by AuNPs) two-photon absorption.展开更多
The precise control and manipulation of micro-and nanoparticles using an optical endoscope are potentially important in biomedical studies,bedside diagnosis and treatment in an aquatic internal organ environment,but t...The precise control and manipulation of micro-and nanoparticles using an optical endoscope are potentially important in biomedical studies,bedside diagnosis and treatment in an aquatic internal organ environment,but they have not yet been achieved.Here,for the first time,we demonstrate optical nonlinear endoscopic tweezers(ONETs)for directly controlling and manipulating aquatic micro-and nanobeads as well as gold nanorods.It is found that two-photon absorption can enhance the trapping force on fluorescent nanobeads by up to four orders of magnitude compared with dielectric nanobeads of the same size.More importantly,two-photon excitation leads to a plasmon-mediated optothermal attracting force on nanorods,which can extend far beyond the focal spot.This new phenomenon facilitates a snowball effect that allows the fast uploading of nanorods to a targeted cell followed by thermal treatment within 1 min.As two-photon absorption allows an operation wavelength at the center of the transmission window of human tissue,our work demonstrates that ONET is potentially an unprecedented tool for precisely specifying the location and dosage of drug particles and for rapidly uploading metallic nanoparticles to individual cancer cells for treatment.展开更多
Four 1,8-naphthalimide hydrazone molecules with different electron-donating groups have been applied in the study of linear and nonlinear optical(NLO)properties.These compounds showed strong green emission in solution...Four 1,8-naphthalimide hydrazone molecules with different electron-donating groups have been applied in the study of linear and nonlinear optical(NLO)properties.These compounds showed strong green emission in solution.Their NLO properties such as two-photon absorption(TPA)behavior with femtosecond laser pulses ca.800 nm and excited-state absorption(ESA)behavior with nanosecond laser pulses at 532 nm were investigated.Compound 4 presented the largest two-photon cross section(550 GM)among them due to two factors:the conjugated length of compound 4 is the longest and the electron-donating ability of compound 4 is the strongest.Different from TPA behavior,compound 2 showed the best nonlinear absorption properties at 532 nm and its nonlinear absorption coef-ficient and third-order nonlinear optical susceptibilitiesχ^(3)were up to 1.41×10^(−10) MKS and 4.65×10^(−12) esu,re-spectively.Through the modification of the structure,the nonlinear optical properties of these compounds at differ-ent wavelengths(532 and 800 nm)were well tuned.The great broad-band nonlinear optical properties indicate hy-drazones are good candidates for organic nonlinear optical absorption materials.展开更多
基金Project supported by the National Natural Science Foundation of China (Grant No. 62174079)the Fund from the Science, Technology, and Innovation Commission of Shenzhen Municipality (Grant Nos. JCYJ20220530113015035, JCYJ20210324120204011, JCYJ20190808121211510, and KQTD2015071710313656)。
文摘Perovskite nanocrystals(NCs) with high two-photon absorption(TPA) cross-section are of great interest due to their potential applications in three-dimensional optical data storage and multiphoton fluorescence microscopy. Among various perovskite materials, FAPbBr_(3) NCs show a better development prospect due to their excellent stability. However, there are few reports on their nonlinear optical properties. In this work, the nonlinear optical behavior of FAPbBr_(3) NCs is studied.The methods of multiphoton absorption photoluminescence saturation and open aperture Z-scan technique were applied to determine the TPA cross-section of FAPbBr_(3)NCs, which was around 2.76 × 10^(-45)cm^(4)·s·photon^(-1) at 800 nm. In addition,temperature-dependent photoluminescence induced by TPA was investigated, and the small longitudinal optical phonon energy and electron–phonon coupling strength was obtained, which confirm the weak Pb–Br interaction. Meanwhile, it is found that the exciton binding energy in FAPbBr_(3) NCs was 69.668 me V, which may be ascribed to the strong hydrogen bond interaction. It is expected that our findings will promote the application of FAPbBr_(3) NCs in optoelectronic devices.
文摘Soliton dynamics are numerically investigated in a two-mode fiber with the two-photon absorption,and the effects of the two-photon absorption on the soliton propagation and interaction are demonstrated in different dispersion regimes.Soliton dynamics depend strictly on the sign and magnitude of the group velocity dispersion(GVD)coefficient of each mode and the strength(coefficient)of the two-photon absorption.The two-photon absorption leads to the soliton collapse,enhances the neighboring soliton interaction in both modes,and increases the energy exchange between the two modes.Finally,an available control is proposed to suppress the effects by the use of the nonlinear gain with filter.
基金Project supported by the National Natural Science Foundation of China(Grant No.11474096)the Science and Technology Commission of Shanghai Municipality,China(Grant Nos.14JC1401500,17ZR146900,and 16520721200)the Higher Education Key Program of He'nan Province of China(Grant No.17A140025)
文摘Improving the up-conversion luminescence efficiency of rare-earth ions via the multi-photon absorption process is crucial in several related application areas. In this work, we theoretically propose a feasible scheme to enhance the resonance-mediated two-photon absorption in Er^(3+) ions by shaping the femtosecond laser field with a rectangle phase modulation. Our theoretical results show that the resonance-mediated two-photon absorption can be decomposed into the on-resonant and near-resonant parts, and the on-resonant part mainly comes from the contribution of laser central frequency components, while the near-resonant part mainly results from the excitation of low and high laser frequency components.So, the rectangle phase modulation can induce a constructive interference between the two parts by properly designing the modulation depth and width, and finally realizes the resonance-mediated two-photon absorption enhancement. Moreover, our results also show that the enhancement efficiency of resonance-mediated two-photon absorption depends on the laser pulse width(or laser spectral bandwidth), final state transition frequency, and intermediate and final state absorption bandwidths. The enhancement efficiency modulation can be attributed to the relative weight manipulation of on-resonant and near-resonant two-photon absorption in the whole excitation process. This study presents a clear physical insight for the quantum control of resonance-mediated two-photon absorption in the rare-earth ions, and there will be an important significance for improving the up-conversion luminescence efficiency of rare-earthions.
文摘A series of novel organic compounds named as CSPI, DPASPI, PSPI DEASPI and HEASPI respectively, with large two-photon absorption has been synthesized and their structures have been determined by 1HNMR and elemental analysis. The highest two-photon pumped (TPP) output /input efficiency is as high as 13.4% for PSPI in DMF with d0 = 0.03 mol/L and the effective two-photon absorption cross section is 8.8(10-48 cm4(s/photon for DPASPI in DMF with d0= 0.05mol/L.
基金the Public Security Theory and Soft Science Research Project(No.2020LLYJSL JY040)the Fundamental Research Funds for the Central Universities(No.LGYB202003).
文摘In this work,a neural network(NN)method is developed for pulse duration inferring for an erbium-doped fiber laser at 1550 nm.Experime nt ally,the interferometric autocorrelation trace is observed clearly with the use of the two-photon absorption(TPA)effect in a GaAs photodiode.The intensity autocorrelation function is curvefitted by the NN with an appropriate performance,and the measuring accuracy is consistent with a commercial autocorrelator.Compared with the Levenberg-Marquardt curve-fitting method,the NN can retrieve the intensity autocorrelation function more stably and has a certain noise reduction ability,simplifying the signal processing for a TPA photodiode-based autocorrelator.
基金the Natural Science Foundation of Shandong Province,China(Grant No.ZR2014AM026).
文摘The properties of one-photon absorption(OPA),emission and two-photon absorption(TPA)of a bipyridine-based zinc ion probe are investigated employing the density functional theory in combination with response functions.The responsive mechanism and coordination mode effect are explored.The structural fluctuation is illustrated by molecular dynamics simulation.The calculated OPA and emission wavelengths of the probe are consistent with the experimental data.It is found that the red-shift of OPA wavelength and the enhancement of TPA intensity are induced by the increased intra-molecular charge transfer mechanism upon metal binding.The structural fluctuation could result in the blue-shift of TPA wavelength and the decrease of the TPA cross section.The TPA properties are quite different among the zinc complexes with different coordination modes.The TPA wavelength of the complexes with two ligands is close to that of the probe,which is in agreement with the experimental observation.
基金Project supported by the National Natural Science Foundation of China(Grant No.61505178).
文摘Cuprous oxide(Cu_(2)O)has attracted plenty of attention for potential nonlinear photonic applications due to its superior third-order nonlinear optical property such as two-photon absorption.In this paper,we investigated the two-photon excitation induced carrier dynamics of a Cu_(2)O thin film prepared by radio-frequency magnetron sputtering,using the femtosecond transient absorption experiments.Biexponential dynamics including an ultrafast carrier scattering(<1 ps)followed by a carrier recombination(>50 ps)were observed.The time constant of carrier scattering under two-photon excitation is larger than that under one-photon excitation,due to the different transition selection rules and smaller absorption coefficient of the two-photon excitation.
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Project supported by the Shandong Provincial Natural Science Foundation,China(Grant No.ZR2020MA078)。
文摘To improve two-photon absorption(TPA)response of a newly synthesized probe,a series of ratiometric two-photon fluorescent Zn^(2+) sensors based on quinoline and DPA moieties have been designed.The one-photon absorption,TPA,and emission properties of the experimental and designed probes before and after coordination with Zn^(2+) are investigated employing the density functional theory in combination with response functions.The design consists of two levels.In the first level of design,five probes are constructed through using several electron acceptors or donors to increase accepting or donating ability of the fluorophores.It shows that all the designed probes have stronger TPA intensities at longer wavelengths with respect to the experimental probe because of the increased intra-molecular charge transfer.Moreover,it is found that the probe 4 built by adding an acyl unit has the largest TPA cross section among the designed structures due to the form of longer conjugated length and more linear backbone.One dimethylamino terminal attached along the skeleton can improve TPA intensity more efficiently than two side amino groups.Therefore,in the second level of design,a new probe 7 is formed by both an acyl unit and a dimethylamino terminal.It exhibits that the TPA cross sections of probe 7 and its zinc complex increase dramatically.Furthermore,the fluorescence quantum yields of the designed probes4 and 7 are calculated in a new way,which makes use of the relation between the computed difference of dipole moment and the measured fluorescence quantum yield.The result shows that our design also improves the fluorescence quantum yield considerably.All in all,the designed probes 4 and 7 not only possess enhanced TPA intensities but also have large differences of emission wavelength upon Zn^(2+) coordination and strong fluorescence intensity,which demonstrates that they are potential ratiometric two-photon fluorescent probes.
基金supported by the National Natural Sci-ence Foundation of China(No.U1904196,No.82073699)the Natural Science Foundation of Henan(No.222300420055).
文摘Partial genetically encoded 4-hy-droxybenzylidene-imidazolinone(HBI)-type chromophores are new promising fluorescent probes,which are suitable for imaging and detection of living cells.How-ever,the lack of infrared chro-mophores hinders the develop-ment seriously.Here more than 30 HBI-type chromophores with reg-ular structure modifications were employed and typical spectral redshift change laws and mechanisms were investigated by quantum methods.Results show that both one-photon spectrum(OPS,absorption/emission)and two-photon absorption(TPA)can achieve large redshift via either extending conjugated lengths of frag-3 or enlarging conjugated areas of frag-1 of HBI skeleton.Spectral redshifts of all chromophores are highly related to intramolecular charge transfer(ICT),but neutral ones are closely related to the total ICT or electron-accept-ing-numbers of frag-3,and the high correlative factor of anions is the aromaticity of frag-2 bridge.The frag-2 bridge with high aromaticity can open a reverse charge transfer channel in anion relative to neutral,obtaining significant redshift.Based on analysis,a new 6-hydroxyl-naphthalene-imidazolinone(HNI)series,which have larger conjugated area in frag-1,are pre-dicted.The OPS and TPA of anionic HNI ones acquire about 76−96 nm and 119−146 nm red-shift relative to traditional HBI series respectively as a whole.The longest emission of anionic HNI-4 realizes more 244 nm redshift relative to HBI-1.Our work clarifies worthy spectral reg-ularities and redshift mechanisms of HBI-type chromophores and provides valuable design strategy for infrared chromophores synthesis in experiment.
基金supported by the Hong Kong RGC-GRF Grant (HKU 705812P)the National Natural Science Foundation of China (11374247 and 11504299)+2 种基金HKU SRT on New Materialsin part by HK-UGC AoE Grants (AoE/P-03/08)the financial support of the National Natural Science Foundation of China(11204231 and 21373156)
文摘It is firmly demonstrated in experiment that the self-absorption(SA) effect can lead to the extinction of the zero-phonon line and the first-order longitudinal optical phonon sideband of free excitonic luminescence of ZnO at room temperature. Moreover, effectiveness degree of SA effect is found to be dependent on both absorption coefficient and travelling distance of emitted photons, as well as even lattice temperature, which is uniquely reflected by the redshift amount in emission peak in ZnO. It is also unambiguously proved that the SA effect still strictly obeys the Beer-Lambert law of absorption. This work not only uncovers the long-term puzzle of significant redshift of emission peak of ZnO at higher temperatures, but also shows that the SA effect may have to be carefully taken into consideration in the study of spontaneous emission, laser and relevant optoelectronic processes in luminescent materials and optoelectronic devices.
文摘The two-photon absorption induced lasing spectrum shows that the synthesized ASPBPh4, trans-4- [p- (N-methyl-N- (hydroxyethyl)amino) styryl]-N-methylpyridinium, has a distinct ef- ficiency of laser frequency up-conversion. This nonlinear optical property of such a kind of com- pounds is related to two-photon absorption (TPA). In our work, we used the intermediate ne- glect of differential overlap (INDO) plus single-excitation configuration interaction (SCI) method to get the basic properties of the molecule, and calculated the second hyperpolarizability and the cross section of two-photon absorption by means of sum-over-state (SOS) expression. The rela- tionship between the structure and the properties is discussed.
基金supported by the National Natural Science Foundation of China (Nos. 51972185, 12174211, 11874232 and 31202117)the Natural Science Foundation of Shandong Province (No. ZR2020ZD38)。
文摘Two triphenylamine-based star-type push-pull chromophores(T1, T2) were designed and synthesized.Triphenylamine serves as the central core and acts as an electron-donating group surrounded by electronwithdrawing pentafluorobenzene or N,N-dimethyl substituted tetrafluorobenzene, which are connected by ethylene bridges. Single-crystal X-ray diffraction confirmed the structures and molecular arrangement of two chromophores. The systematic photophysical research of T1 and T2 absorption characteristics was carried out to gain a better understanding of how structure-property relationships affect the observed nonlinear optical absorption phenomenon. Complementary calculations based on density functional theory(DFT) further confirmed the experimental results. Both chromophores exhibited excellent two-photon absorption(TPA) properties in CH_(2)Cl_(2). Notably, T2 has more remarkable nonlinear optical absorption effects with the TPA cross-section up to 4.24 × 10~7GM. By adjusting the electronic structures of the chromophores through introducing pentafluorobenzene or N,N-dimethyl as functional groups with different electron-donating or withdrawing behaviors, the TPA performance of the small organic molecule could be greatly enhanced. These molecular structures with push-pull systems were excellent candidates for different two-photon applications.
基金supported by the National Natural Science Foundation of China (Nos. 21778001, 21372005)the Anhui Provincial Natural Science Foundation (No. 1608085MB39)+1 种基金the Natural Science Foundation of Education Department of Anhui Province (No. KJ2015A047)the 211 Project of Anhui University
文摘Mitochondria and lysosomes are essential cellular organelles in most eukaryotic cells by playing the physiological roles to support the normal functions of cells, as well as the life of the whole body. To date,small-molecule fluorescent probes have been considered as one of the vital tools for monitoring and visualizing multiple biological analytes. This review summarized the recent advances in small-molecule two-photon fluorescent probes for metal ions, reactive oxygen species(ROS) and reactive sulfur species(RSS), and changes inside micro-environment(e.g., p H, viscosity and polarity) in mitochondria and lysosomes, or served as mitotracker and lysotracker with the assistance of two-photon microscopy.
基金supported by the Guangdong Innovative Research Team Program of China (201101C0105067115)the National Natural Science Foundation of China (21673155)+3 种基金the Young Scientists Fund of the National Natural Science Foundation of China (51603069)the Scientific Research Staring Natural Science Foundation of Guangdong Province, China (2016A030310432)the Fundamental Research Funds for the Central Universities and China Postdoctoral Science Foundation (2016M592485)Ministry of Education of Singapore (R-143-000-607-112)
文摘Two-photon excitation microscopy(2 PEM) has been known as a noninvasive and powerful bio-imaging tool for studying living cells, intact tissues and living animals because of their unique advantages such as localized excitation, deep tissue penetration as well as less photo-damage. However, the major limitations that hinder its practical applications in biological systems are low two-photon absorption cross sections of conventional fluorescence probes. Conjugated polymer nanoparticles(CPNs) consisting of highly fluorescent conjugated polymers are promising fluorescent probes for 2 PEM due to their unique advantages including large two-photon absorption cross sections, high fluorescence quantum yield, good photo-stability and biocompatibility, facile chemical synthesis, tunable optical properties as well as versatile surface modifications. This account summarizes the recent efforts of our group on development of novel polyfluorene based CPNs as 2 PEM contrast agents for live cell imaging.
基金the support by the Deutsche Forschungsgemeinschaft(DFG)in the framework of Research Training Group Tip-and laser-based 3D-Nanofcibrication in extended macroscopic working areas(GRK 2182)at the Technische Universitat Ilmenau,Germanyfinancial support from the DFG from the grant RE3012/4-1.
文摘Since the first realization of two-photon direct laser writing(DLW)in Maruo et al.(Opt Lett 22:132-134,1997),the manufacturing using direct laser writing techniques spread out in many laboratories all over the world.Photosensitive materials with different material properties open a new field for micro-and nanofabrication.The achievable structuring resolution using this technique is reported to be sub-100 nm(Paz et al.in J.Laser Appl.24:042004,2012),while a smallest linewidth of 25 nm could be shown in Tan et al.(Appl Phys Lett 90:071106,2007).In our approach,the combination of DLW with the nanopositioning and nanomeasuring machine NMM-1 offers an improvement of the technique from the engineering side regarding the ultra-precise positioning(Weidenfeller et al.in Adv Fabr Technol Micro/Nano Opt Photon Ⅺ 10544:105440E,2018).One big benefit besides the high positioning resolution of 0.1 nm is offered by the positioning range of 25 mm×25 mm×5 mm(Jager et al.in Technisches Messen 67:319-323,2000;Manske et al.in Meas Sci Technol 18:520-527,2007).Thus,a trans-scale fabrication without any stitching or combination of different positioning systems is necessary.The immense synergy between the highly precise positioning and the DLW is demonstrated by the realization of resist lines and trenches whose center-to-center distance undergoes the modified diffraction limit for two-photon processes.The precise positioning accuracy enables a defined distance between illuminated lines.Hence,with a comparable huge width of the trenches of 1.655|im due to a low effective numerical aperture of 0.16,a resist line of 30 nm between two written trenches could be achieved.Although the interrelationships for achieving such narrow trenches have not yet been clarified,much smaller resist lines and trench widths are possible with this approach in the near future.
基金We thank the Japan Society for the Promotion of Science and the Ministry of Education,Culture,Sports,Science and Technology of Japan for financial supportGrant-in-Aid for Challenging Exploratory Research(KM,24656040)+4 种基金Grant-in-Aid for Scientific Research on Innovative Areas‘Integrated Organic Synthesis’(KM,22106545 and 24106746)Grant-inAid for Young Scientists(KI,30455274)Japan Science and Technology Agency for financial support of e-ASIA JRPsupported by the Research Foundation for Opto-Science and Technologyby Grant for Environmental Research Projects from The Sumitomo Foundation and the Collaborative Research Program of the Institute for Chemical Research,Kyoto University(grant 2012-14)
文摘We demonstrate a bottom-up approach to fabricating a visible light-driven titania photocatalyst device bearing an embeddedtwo-dimensional (2D) array of gold nanoparticles (AuNPs) as a near-field light-generating layer. The device is a layered structureprepared by depositing a 2D array of AuNPs on a transparent conductive substrate (10 nm indium tin oxide (ITO) layer on quartz),coating the 2D array of AuNPs with a monolayer of trimethoxyoctylsilane (TMOS), and depositing titania nanocrystals on the anchoringmolecule (TMOS) layer. The visible light activity of the device was tested using photocatalytic degradation of methylene blue (MB) byilluminating the device with visible light (700 nm light) and ultraviolet (UV) light (250–380 nm). The localized surface plasmonresonance peak of the 36 nm AuNP 2D array is around 700 nm with a full-width at half-maximum of 350 nm. In comparison with othercontrol samples, the device showed the highest photocatalytic activity with visible irradiation, which was 1.7 times higher than that oftitania with UV irradiation. The origin of the visible light activity was confirmed by both quadratic incident light power dependency andaction spectrum to be plasmon-induced (near-field enhancement by AuNPs) two-photon absorption.
文摘The precise control and manipulation of micro-and nanoparticles using an optical endoscope are potentially important in biomedical studies,bedside diagnosis and treatment in an aquatic internal organ environment,but they have not yet been achieved.Here,for the first time,we demonstrate optical nonlinear endoscopic tweezers(ONETs)for directly controlling and manipulating aquatic micro-and nanobeads as well as gold nanorods.It is found that two-photon absorption can enhance the trapping force on fluorescent nanobeads by up to four orders of magnitude compared with dielectric nanobeads of the same size.More importantly,two-photon excitation leads to a plasmon-mediated optothermal attracting force on nanorods,which can extend far beyond the focal spot.This new phenomenon facilitates a snowball effect that allows the fast uploading of nanorods to a targeted cell followed by thermal treatment within 1 min.As two-photon absorption allows an operation wavelength at the center of the transmission window of human tissue,our work demonstrates that ONET is potentially an unprecedented tool for precisely specifying the location and dosage of drug particles and for rapidly uploading metallic nanoparticles to individual cancer cells for treatment.
基金The authors thank the National Natural Science Foundation of China(Nos.21071105,20902065 and 21176164).
文摘Four 1,8-naphthalimide hydrazone molecules with different electron-donating groups have been applied in the study of linear and nonlinear optical(NLO)properties.These compounds showed strong green emission in solution.Their NLO properties such as two-photon absorption(TPA)behavior with femtosecond laser pulses ca.800 nm and excited-state absorption(ESA)behavior with nanosecond laser pulses at 532 nm were investigated.Compound 4 presented the largest two-photon cross section(550 GM)among them due to two factors:the conjugated length of compound 4 is the longest and the electron-donating ability of compound 4 is the strongest.Different from TPA behavior,compound 2 showed the best nonlinear absorption properties at 532 nm and its nonlinear absorption coef-ficient and third-order nonlinear optical susceptibilitiesχ^(3)were up to 1.41×10^(−10) MKS and 4.65×10^(−12) esu,re-spectively.Through the modification of the structure,the nonlinear optical properties of these compounds at differ-ent wavelengths(532 and 800 nm)were well tuned.The great broad-band nonlinear optical properties indicate hy-drazones are good candidates for organic nonlinear optical absorption materials.
