This paper reports the synthesis and the nonlinear optical property of a series of new chromophores which contain furan ring as the only conjugation bridge for the first time. They are characterized by UV-VIS, FT-IR, ...This paper reports the synthesis and the nonlinear optical property of a series of new chromophores which contain furan ring as the only conjugation bridge for the first time. They are characterized by UV-VIS, FT-IR, H-1 NMR, MS and elemental analysis. Their dipole moment and the first-order molecular hyperpolarizability (beta) are calculated and compared with those or the analogues containing either benzene or thiophene as file conjugation bridge.展开更多
Third-order nonlinear optical (NLO) materials have broad application prospects in high-density data storage, optical computer, modern laser technology, and other high-tech industries. The structures and frequencies of...Third-order nonlinear optical (NLO) materials have broad application prospects in high-density data storage, optical computer, modern laser technology, and other high-tech industries. The structures and frequencies of Dinaphtho[2,3-b:2’,3’-d]thiophene-5,7,12,13-tetraone (DNTTRA) and its 36 derivatives containing azobenzene were calculated by using density functional theory B3LYP and M06-2X methods at 6-311++g(d, p) level, respectively. Besides, the atomic charges of natural bond orbitals (NBO) were analyzed. The frontier orbitals and electron absorption spectra of A-G5 molecule were calculated by TD-DFT (TD-B3LYP/6-311++g(d, p) and TD-M06-2X/6-311++g(d, p)). The NLO properties were calculated by effective finite field FF method and self-compiled program. The results show that 36 molecules of these six series are D-π-A-π-D structures. The third-order NLO coefficients γ (second-order hyperpolarizability) of the D series molecules are the largest among the six series, reaching 10<sup>7</sup> atomic units (10<sup><span style="color:#4F4F4F;font-family:-apple-system, " font-size:14px;white-space:normal;background-color:#ffffff;"="">-</span>33</sup> esu) of order of magnitude, showing good third-order NLO properties. Last, the third-order NLO properties of the azobenzene ring can be improved by introducing strong electron donor groups (e.g. -N(CH<sub>3</sub>)<sub>2</sub> or -NHCH<sub>3</sub>) in the azobenzene ring, so that the third-order NLO materials with good performance can be obtained.展开更多
AgGa_(1-x)In_(x)Se_(2)polycrystals were synthesized by the method of mechanical oscillation and temperature oscillation.X-ray diffraction spectra of polycrystal powder are conformable with the JCPDS cards.Lattice cons...AgGa_(1-x)In_(x)Se_(2)polycrystals were synthesized by the method of mechanical oscillation and temperature oscillation.X-ray diffraction spectra of polycrystal powder are conformable with the JCPDS cards.Lattice constants a and c calculated from the XRD were found to obey Vegard's law.The melting point of AgGa_(0.8)In_(0.2)Se_(2)obtained by means of differential scanning calorimetry(DSC)is 796.53℃.The DSC curve also show that there are no other transformation points below the melting point.The results indicate that polycrystalline materials synthesized by the method mentioned above are high-quality and can be used to grow single crystals by the vertical Bridgman technology.展开更多
All-optical poling （AOP） of a crosslinkable polymer based on hexamethoxymethyl melamine （HMMM） and Disperse red 1 （DR-1） is investigated. It is＇found that the saturation second harmonic generation （SHG） inten...All-optical poling （AOP） of a crosslinkable polymer based on hexamethoxymethyl melamine （HMMM） and Disperse red 1 （DR-1） is investigated. It is＇found that the saturation second harmonic generation （SHG） intensity decreases significantly with the increase of the sample temperature from 33℃ to 63℃. From the perspective of energy equilibrium, the main factors of AOP are analysed, and by introducing the classical ideal gas model, a simple inequation is first deduced to describe the requirement of realizing AOP.展开更多
Single crystals of undoped (pure) and barium nitrate (Ba (NO3)2)-doped L-Valinium Picrate (LVP) were grown from aqueous solution by slow evaporation technique. Morphological changes have been observed when Ba (NO3)2) ...Single crystals of undoped (pure) and barium nitrate (Ba (NO3)2)-doped L-Valinium Picrate (LVP) were grown from aqueous solution by slow evaporation technique. Morphological changes have been observed when Ba (NO3)2) is doped into LVP crystals. The dopant concentration in the crystals was measured by ICP technique. Slight changes in the unit cell parameter of LVP after doping with Ba (NO3)2) have been detected. The powder X-ray diffraction of the grown crystals has been recorded and the various planes of reflection identified shows shift in the peak positions. FTIR and UV spectra reveal the functional group identification and optical property of the grown crystals. The relative second harmonic generation (SHG) efficiency measurements revealed that both 5 and 10 mol % of Ba (NO3)2) in LVP enhanced the SHG efficiency by 92.85 and 160.59 times that of KDP respectively. However, at higher concentration, SHG efficiency is not increased but rather decreased from it undoped condition. Microhardness studies show that hardness number (Hv) increased with increase in load for all the grown crystals of this work.展开更多
Barium metaborate (BaB 2O 4) exists in two forms the high temperature for m α phase and the low temperature form β phase,with the phase transition poi nt at around 925℃.The low temperature phase (β BBO) is an exce...Barium metaborate (BaB 2O 4) exists in two forms the high temperature for m α phase and the low temperature form β phase,with the phase transition poi nt at around 925℃.The low temperature phase (β BBO) is an excellent NLO cryst al for UV region,while the high temperature one (α BBO) is known as a good bir efringent material.α BBO crystal possesses better transparency in the ultravio let region compared with commonly used YVO 4 and CaCO 3 crystals.However,due t o phase transition problem,it is difficult to grow single α BBO crystals by D CZ method,which restricts its wider application.α BBO crystal usually cracks upon cooling resulted from phase transition to β phase.Therefore,it is difficult to grow β BBO single crystals directly from pure BaB 2O 4 mel t;however,to grow single crystals of α BBO is not easy,either. Our recent experiments showed that one could avoid cracking of α BBO cryst als by Sr 2+ doping.This minute amount of Sr 2+ plays the role of structure stabilizer,which inhibits structural reconstruction. In this way,Sr 2+ d op ed BBO single crystals do not subject to phase transition from 925℃ down to roo m temperature. We have mow successfully grown out α BBO single crystals 30mm in diameter by D CZ method from Sr x Ba 1- x BO 4 melt with Sr concentration 0.3 0 .5%.The ratation rate is 10 15r/min,pulling speed is 1 2mm/h.Preliminary tests revealed that its structure and physic chemical properties were almost identic al to those grown from pure melts.These Sr 2+ doped α BBO crystals are no w being widely used in optical isolators.展开更多
Optical selection rules fundamentally determine the optical transitions between energy states in a variety of physical systems,from hydrogen atoms to bulk crystals such as gallium arsenide.These rules are important fo...Optical selection rules fundamentally determine the optical transitions between energy states in a variety of physical systems,from hydrogen atoms to bulk crystals such as gallium arsenide.These rules are important for optoelectronic applications such as lasers,energy-dispersive X-ray spectroscopy,and quantum computation.Recently,single-layer transition metal dichalcogenides have been found to exhibit valleys in momentum space with nontrivial Berry curvature and excitons with large binding energy.However,there has been little study of how the unique valley degree of freedom combined with the strong excitonic effect influences the nonlinear optical excitation.Here,we report the discovery of nonlinear optical selection rules in monolayer WS2,an important candidate for visible 2D optoelectronics because of its high quantum yield and large direct bandgap.We experimentally demonstrated this principle for second-harmonic generation and two-photon luminescence(TPL).Moreover,the circularly polarized TPL and the study of its dynamics evince a sub-ps interexciton relaxation(2p R 1s).The discovery of this new optical selection rule in a valleytronic 2D system not only considerably enhances knowledge in this area but also establishes a foundation for the control of optical transitions that will be crucial for valley optoelectronic device applications such as 2D valley-polarized THz sources with 2p–1s transitions,optical switches,and coherent control for quantum computing.展开更多
Interests surrounding the development of on-chip nonlinear optical devices have been consistently growing in the past decades due to the tremendous applications,such as quantum photonics,all-optical communications,opt...Interests surrounding the development of on-chip nonlinear optical devices have been consistently growing in the past decades due to the tremendous applications,such as quantum photonics,all-optical communications,optical computing,on-chip metrology,and sensing.Developing efficient on-chip nonlinear optical devices to meet the requirements of those applications brings the need for new directions to improve the existing photonic approaches.Recent research has directed the field of on-chip nonlinear optics toward the hybrid integration of two-dimensional layered materials(such as graphene,transition metal dichalcogenides,and black phosphorous)with various integrated platforms.The combination of well-known photonic chip design platforms(e.g.,silicon,silicon nitride)and different two-dimensional layered materials has opened the road for more versatile and efficient structures and devices,which has the great potential to unlock numerous new possibilities.This review discusses the modeling and characterization of different hybrid photonic integration structures with two-dimensional materials,highlights the current state of the art examples,and presents an outlook for future prospects.展开更多
Nowadays,realizing miniaturized nonlinear optical(NLO)device is crucial to meet the growing needs in on-chip nanophotonics as well as compact integrated devices.The strong optical nonlinearities,ultrafast photoexcitat...Nowadays,realizing miniaturized nonlinear optical(NLO)device is crucial to meet the growing needs in on-chip nanophotonics as well as compact integrated devices.The strong optical nonlinearities,ultrafast photoexcitation dynamics,available exciton effects as well as without lattice matching make two-dimensional(2D)layered materials potential candidates for integrated and nano-scale NLO devices.Herein,a novel and inversion symmetry broken 2D layered SnP_(2)S_(6)with strong second-harmonic and third-harmonic response has been reported for the first time.The second-order susceptibility(χ^(2))of SnP_(2)S_(6)flakes can reach up to 4.06×10^(−9)m·V^(−1)under 810 nm excitation wavelength,which is around 1–2 orders of magnitude higher than that of most reported 2D materials.In addition,the NLO response of 2D SnP_(2)S_(6)can break through the limitation of odd/even layers and exhibit broadband spectral response.Moreover,since the second-harmonic signal is closely related to structure variation,the second-harmonic response in 2D SnP_(2)S_(6)is extremely sensitive to polarization angle and temperature,which is beneficial to some specific applications.The excellent NLO response in 2D SnP_(2)S_(6)provides a new arena for realizing miniaturized NLO devices in the future.展开更多
基金the National Natural Science Foundation of China(No.29774018) a grant from the National Key Fundamental Research Program of China.
文摘This paper reports the synthesis and the nonlinear optical property of a series of new chromophores which contain furan ring as the only conjugation bridge for the first time. They are characterized by UV-VIS, FT-IR, H-1 NMR, MS and elemental analysis. Their dipole moment and the first-order molecular hyperpolarizability (beta) are calculated and compared with those or the analogues containing either benzene or thiophene as file conjugation bridge.
文摘Third-order nonlinear optical (NLO) materials have broad application prospects in high-density data storage, optical computer, modern laser technology, and other high-tech industries. The structures and frequencies of Dinaphtho[2,3-b:2’,3’-d]thiophene-5,7,12,13-tetraone (DNTTRA) and its 36 derivatives containing azobenzene were calculated by using density functional theory B3LYP and M06-2X methods at 6-311++g(d, p) level, respectively. Besides, the atomic charges of natural bond orbitals (NBO) were analyzed. The frontier orbitals and electron absorption spectra of A-G5 molecule were calculated by TD-DFT (TD-B3LYP/6-311++g(d, p) and TD-M06-2X/6-311++g(d, p)). The NLO properties were calculated by effective finite field FF method and self-compiled program. The results show that 36 molecules of these six series are D-π-A-π-D structures. The third-order NLO coefficients γ (second-order hyperpolarizability) of the D series molecules are the largest among the six series, reaching 10<sup>7</sup> atomic units (10<sup><span style="color:#4F4F4F;font-family:-apple-system, " font-size:14px;white-space:normal;background-color:#ffffff;"="">-</span>33</sup> esu) of order of magnitude, showing good third-order NLO properties. Last, the third-order NLO properties of the azobenzene ring can be improved by introducing strong electron donor groups (e.g. -N(CH<sub>3</sub>)<sub>2</sub> or -NHCH<sub>3</sub>) in the azobenzene ring, so that the third-order NLO materials with good performance can be obtained.
基金Project supported by the Specialized Research Fund for the Doctoral Program of Higher Education(20040610024)
文摘AgGa_(1-x)In_(x)Se_(2)polycrystals were synthesized by the method of mechanical oscillation and temperature oscillation.X-ray diffraction spectra of polycrystal powder are conformable with the JCPDS cards.Lattice constants a and c calculated from the XRD were found to obey Vegard's law.The melting point of AgGa_(0.8)In_(0.2)Se_(2)obtained by means of differential scanning calorimetry(DSC)is 796.53℃.The DSC curve also show that there are no other transformation points below the melting point.The results indicate that polycrystalline materials synthesized by the method mentioned above are high-quality and can be used to grow single crystals by the vertical Bridgman technology.
基金Supported by the National Natural Science Foundation of China under Grant Nos 60178030 and 90201016.
文摘All-optical poling （AOP） of a crosslinkable polymer based on hexamethoxymethyl melamine （HMMM） and Disperse red 1 （DR-1） is investigated. It is＇found that the saturation second harmonic generation （SHG） intensity decreases significantly with the increase of the sample temperature from 33℃ to 63℃. From the perspective of energy equilibrium, the main factors of AOP are analysed, and by introducing the classical ideal gas model, a simple inequation is first deduced to describe the requirement of realizing AOP.
文摘Single crystals of undoped (pure) and barium nitrate (Ba (NO3)2)-doped L-Valinium Picrate (LVP) were grown from aqueous solution by slow evaporation technique. Morphological changes have been observed when Ba (NO3)2) is doped into LVP crystals. The dopant concentration in the crystals was measured by ICP technique. Slight changes in the unit cell parameter of LVP after doping with Ba (NO3)2) have been detected. The powder X-ray diffraction of the grown crystals has been recorded and the various planes of reflection identified shows shift in the peak positions. FTIR and UV spectra reveal the functional group identification and optical property of the grown crystals. The relative second harmonic generation (SHG) efficiency measurements revealed that both 5 and 10 mol % of Ba (NO3)2) in LVP enhanced the SHG efficiency by 92.85 and 160.59 times that of KDP respectively. However, at higher concentration, SHG efficiency is not increased but rather decreased from it undoped condition. Microhardness studies show that hardness number (Hv) increased with increase in load for all the grown crystals of this work.
文摘Barium metaborate (BaB 2O 4) exists in two forms the high temperature for m α phase and the low temperature form β phase,with the phase transition poi nt at around 925℃.The low temperature phase (β BBO) is an excellent NLO cryst al for UV region,while the high temperature one (α BBO) is known as a good bir efringent material.α BBO crystal possesses better transparency in the ultravio let region compared with commonly used YVO 4 and CaCO 3 crystals.However,due t o phase transition problem,it is difficult to grow single α BBO crystals by D CZ method,which restricts its wider application.α BBO crystal usually cracks upon cooling resulted from phase transition to β phase.Therefore,it is difficult to grow β BBO single crystals directly from pure BaB 2O 4 mel t;however,to grow single crystals of α BBO is not easy,either. Our recent experiments showed that one could avoid cracking of α BBO cryst als by Sr 2+ doping.This minute amount of Sr 2+ plays the role of structure stabilizer,which inhibits structural reconstruction. In this way,Sr 2+ d op ed BBO single crystals do not subject to phase transition from 925℃ down to roo m temperature. We have mow successfully grown out α BBO single crystals 30mm in diameter by D CZ method from Sr x Ba 1- x BO 4 melt with Sr concentration 0.3 0 .5%.The ratation rate is 10 15r/min,pulling speed is 1 2mm/h.Preliminary tests revealed that its structure and physic chemical properties were almost identic al to those grown from pure melts.These Sr 2+ doped α BBO crystals are no w being widely used in optical isolators.
基金This work was supported by the“Light-Material Interactions in Energy Conversion”Energy Frontier Research Center funded by the U.S.Department of Energy,Office of Science,Office of Basic Energy Sciences under Award Number DE-AC02-05CH11231.
文摘Optical selection rules fundamentally determine the optical transitions between energy states in a variety of physical systems,from hydrogen atoms to bulk crystals such as gallium arsenide.These rules are important for optoelectronic applications such as lasers,energy-dispersive X-ray spectroscopy,and quantum computation.Recently,single-layer transition metal dichalcogenides have been found to exhibit valleys in momentum space with nontrivial Berry curvature and excitons with large binding energy.However,there has been little study of how the unique valley degree of freedom combined with the strong excitonic effect influences the nonlinear optical excitation.Here,we report the discovery of nonlinear optical selection rules in monolayer WS2,an important candidate for visible 2D optoelectronics because of its high quantum yield and large direct bandgap.We experimentally demonstrated this principle for second-harmonic generation and two-photon luminescence(TPL).Moreover,the circularly polarized TPL and the study of its dynamics evince a sub-ps interexciton relaxation(2p R 1s).The discovery of this new optical selection rule in a valleytronic 2D system not only considerably enhances knowledge in this area but also establishes a foundation for the control of optical transitions that will be crucial for valley optoelectronic device applications such as 2D valley-polarized THz sources with 2p–1s transitions,optical switches,and coherent control for quantum computing.
基金supported by Paris Saclay University within the Centre for Nanoscience and Nanotechnology(C2N)in France and Aalto University in Finland.ZS thanks fundings from the Academy of Finland(314810,333982,336144,336818,352780,353364)the Academy of Finland Flagship Programme(320167,PREIN)the EU H2020-MSCA-RISE-872049(IPN-Bio),and ERC(834742).
文摘Interests surrounding the development of on-chip nonlinear optical devices have been consistently growing in the past decades due to the tremendous applications,such as quantum photonics,all-optical communications,optical computing,on-chip metrology,and sensing.Developing efficient on-chip nonlinear optical devices to meet the requirements of those applications brings the need for new directions to improve the existing photonic approaches.Recent research has directed the field of on-chip nonlinear optics toward the hybrid integration of two-dimensional layered materials(such as graphene,transition metal dichalcogenides,and black phosphorous)with various integrated platforms.The combination of well-known photonic chip design platforms(e.g.,silicon,silicon nitride)and different two-dimensional layered materials has opened the road for more versatile and efficient structures and devices,which has the great potential to unlock numerous new possibilities.This review discusses the modeling and characterization of different hybrid photonic integration structures with two-dimensional materials,highlights the current state of the art examples,and presents an outlook for future prospects.
基金the National Natural Science Foundation of China(Nos.21825103 and 51727809)Hubei Provincial Nature Science Foundation of China(No.2019CFA002)+1 种基金the Fundamental Research Funds for the Central Universities(No.2019kfyXMBZ018)China Postdoctoral Science Foundation(No.2020M682338).
文摘Nowadays,realizing miniaturized nonlinear optical(NLO)device is crucial to meet the growing needs in on-chip nanophotonics as well as compact integrated devices.The strong optical nonlinearities,ultrafast photoexcitation dynamics,available exciton effects as well as without lattice matching make two-dimensional(2D)layered materials potential candidates for integrated and nano-scale NLO devices.Herein,a novel and inversion symmetry broken 2D layered SnP_(2)S_(6)with strong second-harmonic and third-harmonic response has been reported for the first time.The second-order susceptibility(χ^(2))of SnP_(2)S_(6)flakes can reach up to 4.06×10^(−9)m·V^(−1)under 810 nm excitation wavelength,which is around 1–2 orders of magnitude higher than that of most reported 2D materials.In addition,the NLO response of 2D SnP_(2)S_(6)can break through the limitation of odd/even layers and exhibit broadband spectral response.Moreover,since the second-harmonic signal is closely related to structure variation,the second-harmonic response in 2D SnP_(2)S_(6)is extremely sensitive to polarization angle and temperature,which is beneficial to some specific applications.The excellent NLO response in 2D SnP_(2)S_(6)provides a new arena for realizing miniaturized NLO devices in the future.
