Polarization-dependent second harmonic generation is a widely utilized technique for characterizing symmetry.However,in collinear reflective geometry,the essential beam-splitting device significantly influences both t...Polarization-dependent second harmonic generation is a widely utilized technique for characterizing symmetry.However,in collinear reflective geometry,the essential beam-splitting device significantly influences both the polarization state of the fundamental and harmonic beams,thereby affecting the accuracy of the obtained second-order nonlinear susceptibility.Here,we propose a data correction method to solve this problem to obtain accurate secondorder nonlinear susceptibility.The feasibility and generality of the method are demonstrated through theoretical and experimental validation.展开更多
Second harmonic generation(SHG),a fundamental and widely-studied phenomenon in nonlinear optics,has attracted significant attention for its ability to convert fundamental frequencies into their second harmonics.While ...Second harmonic generation(SHG),a fundamental and widely-studied phenomenon in nonlinear optics,has attracted significant attention for its ability to convert fundamental frequencies into their second harmonics.While the dominant SHG research has been focused on the optical and infrared regimes,its investigation in the microwave range presents challenges due to the requirements of materials with higher nonlinear coefficients and high-power microwave sources.Here,we provide an overview of methods together with underlying mechanisms for SHG in microwave frequencies,and discuss prospects and insights into the future developments of SHG-based technologies.The discussions on both numerical analyses and experimental studies will offer guidance for further SHG research and communication advancements in microwave regime.展开更多
We investigate high-order harmonic generations(HHGs)under comparison of Weyl cones in two types.Due to the hyperboloidal electron pocket structure,strong noncentrosymmetrical generations in high orders are observed ar...We investigate high-order harmonic generations(HHGs)under comparison of Weyl cones in two types.Due to the hyperboloidal electron pocket structure,strong noncentrosymmetrical generations in high orders are observed around a single type-ⅡWeyl point,especially at zero frequency.Such a remarkable DC signal is proved to have attributions from the intraband transition after spectral decomposition.Under weak pulse electric field,the linear optical response of a nontilted Weyl cone is consistent with the Kubo theory.With extensive numerical simulations,we conclude that the non-zero chemical potential can enhance the even-order generations,from the slightly tilted system to the over-tilted systems.In consideration of dynamical symmetries,type-Ⅰand type-ⅡWeyl cones also show different selective responses under the circularly polarized light.Finally,using a more realistic model containing two pairs of Weyl points,we demonstrate that paired Weyl points with opposite chirality can suppress the overall even-order generations.展开更多
The development of nonlinear optical(NLO)crystals with excellent performance has been the goal of numerous researchers.Herein,iodide has been successfully introduced into lead 2,6-pyridinedicarboxylates to rationally ...The development of nonlinear optical(NLO)crystals with excellent performance has been the goal of numerous researchers.Herein,iodide has been successfully introduced into lead 2,6-pyridinedicarboxylates to rationally synthesize a series of new stable NLO crystals,APb_(2)(C_(7)H_(3)NO_(4))_(2)I(A=K,Rb,Cs),via a mild mix-solvothermal method.展开更多
Ultraviolet nonlinear optical (UV NLO) crystals are the key and basic materials for solid-state lasers.Phosphates as UV NLO crystals are limited in practical applications due to their weak second-harmonic generation (...Ultraviolet nonlinear optical (UV NLO) crystals are the key and basic materials for solid-state lasers.Phosphates as UV NLO crystals are limited in practical applications due to their weak second-harmonic generation (SHG) response.In this work,two non-centrosymmetric pyro-phosphates of K_(3)SrBi(P_(2)O_(7))_(2) and Rb_(3)SrBi(P_(2)O_(7))_(2) have been synthesized by a high-temperature solution method.Systematic property measurements show that they both have short UV cut-off edges (∼240 nm) and large SHG responses (4 × KDP for K_(3)SrBi(P_(2)O_(7))_(2) and 2.1 × KDP for Rb_(3)SrBi(P_(2)O_(7))_(2)).Thus,they are both promising UV NLO candidates.In particular,K_(3)SrBi(P_(2)O_(7))_(2) shows the strongest SHG response in the family of A_(3)BBi(P_(2)O_(7))_(2) (A = K,Rb,B = Sr;A = Rb,Cs,B = Ba,Pb),which is about twice higher than that of isomorphic Rb_(3)SrBi(P_(2)O_(7))_(2).The study of the structure–property relationship shows that the synergistic effect of P_(2)O_(7) dimers and BiO6 polyhedra is the main contribution to their excellent NLO properties.And better orientations of P_(2)O_(7) dimers and larger distortion of BiO6 units play important roles in enhancing the SHG response of K_(3)SrBi(P_(2)O_(7))_(2).展开更多
A new mixed alkali hydro-isocyanurate,RbNa(HC_(3)N_(3)O_(3))·2H_(2)O,with the noncentrosymmetric space group Pna21(No.33),has been successfully grown by a hydrothermal method.The structure can be described as 2D ...A new mixed alkali hydro-isocyanurate,RbNa(HC_(3)N_(3)O_(3))·2H_(2)O,with the noncentrosymmetric space group Pna21(No.33),has been successfully grown by a hydrothermal method.The structure can be described as 2D wavy[Na(HC_(3)N_(3)O_(3))O_(4)]∞layers separated by Rb atoms.The UV-vis diffuse reflection measurement revealed that RbNa(HC_(3)N_(3)O_(3))·2H_(2)O has a large band gap of 5.10 eV,corresponding to the UV cutoff edge of 241 nm.The polarizing microscope measurement of a micron-sized single crystal shows that RbNa(HC_(3)N_(3)O_(3))·2H_(2)O has a large birefringence of 0.194.The powder SHG measurement indicated that RbNa(HC_(3)N_(3)O_(3))·2H_(2)O exhibits a strong SHG effect that is 5.3 times that of KH_(2)PO_(4)(KDP)and can realize phase-matching in the visible and UV region.Moreover,the differences in the SHG responses between RbNa(HC_(3)N_(3)O_(3))·2H_(2)O and two isostructural compounds have been investigated,which depend heavily on the structural modulation of the(HC_(3)N_(3)O_(3))2-group by cations.Meanwhile,the electronic structures and optical properties were well analyzed using DFT methods.展开更多
It is generally considered difficult for traditional sulfates to exhibit strong second harmonic generation(SHG)responses and large birefringence values because SO_(4)groups are nonpolar tetrahedral structures.However,...It is generally considered difficult for traditional sulfates to exhibit strong second harmonic generation(SHG)responses and large birefringence values because SO_(4)groups are nonpolar tetrahedral structures.However,by theoretical calculations,we found that polar tetrahedral S_(2)O_(3)shows great improvements in anisotropy and second order polarizability compared to SO_(4)while the wide band gap can be preserved.展开更多
Infrared(IR)nonlinear optical(NLO)materials have attracted tremendous interest for civil and military applications,but it remains a great contemporary challenge to develop high-effciency NLO crystals that possess suff...Infrared(IR)nonlinear optical(NLO)materials have attracted tremendous interest for civil and military applications,but it remains a great contemporary challenge to develop high-effciency NLO crystals that possess suffciently high second-harmonic generation(SHG)effciencies coupled to wide transparency ranges and high laser damage thresholds.A series of new hydrous rare-earth iodates RE(IO_(3))_(3)·(H_(2)O)(RE=Y 1,Eu 2)and La_(2)(IO_(3))_(6)(H_(2)O)(3)have been synthesized through facile hydrothermal methods.1 and 2 are isostructural,crystallizing in the polar space group P21,while 3 crystallizes in the polar space group Pc.1-3 feature three-dimensional(3D)frameworks composed of alternately connected corner-shared dis torted[REO_(x)]polyhedra(RE=Y,Eu,and La;x=8,9)and[IO_(3)]^(−)groups.Optical studies showed that 1–3 exhibit good NLO properties,including strong SHG intensities(3.0×(1),4.5×(2),and 1.5×KH_(2)PO_(4)(3)),large band gaps(4.12(1),4.36(2),and 4.24 eV(3),with 2 possessing the largest band gap among the known SHG-active rare-earth-based iodates,high laser damage thresholds(LDT)(53×(1),43×(2),and 44×AgGaS_(2)(3)),and wide transparency ranges(ca.3.0–11.3μm)in the mid-IR region covering two criti cal IR transparency windows;1–3 are therefore potential candidate NLO materials.Density functional theory calculations on 1–3 confirm that their strong SHG responses and large band gaps are mainly derived from the synergistic effect of[IO_(3)]^(−)groups and rare-earth oxide polyhedra[REOx]in their 3D frameworks.We conclude that the introduction of rare-earth cations with moderate electropositivity into iodates may optimize the balance between SHG effciency and optical band gaps,the key requirement for high-performance NLO materials for practical applications.展开更多
The exploration of new infrared(IR)nonlinear optical(NLO)crystals with large second-harmonic generation(SHG)responses and high laser-induced damage thresholds(LIDTs)concurrently is urgently needed and challenging.Here...The exploration of new infrared(IR)nonlinear optical(NLO)crystals with large second-harmonic generation(SHG)responses and high laser-induced damage thresholds(LIDTs)concurrently is urgently needed and challenging.Herein,the first-type of noncentrosymmetric(NCS)alkali metal Ag-based thiophosphates KAg_(2)PS_(4)(1)and(Na_(0.30)K_(0.70))Ag_(2)PS_(4)(2)were successfully synthesized using a high-temperature solid-state method.展开更多
Infrared(IR)nonlinear optical(NLO)materials with simultaneous strong NLO coefficient and high laserinduced damaged threshold(LIDT)are the urgently desired optical performance NLO materials in laser application.Here,tw...Infrared(IR)nonlinear optical(NLO)materials with simultaneous strong NLO coefficient and high laserinduced damaged threshold(LIDT)are the urgently desired optical performance NLO materials in laser application.Here,two different electropositive alkali elements are concurrently incorporated into a tetrahedral GaS_(4) anionic framework,affording the first polar quaternary sulphide CsLiGa_(6)S_(10)(CLGS)with mixed ordered alkali cations through the solid-state method.CLGS displays a wide band gap(3.25 eV)originating from the GaS_(4) anionic framework and assistant of the‘dimensional reduction’effect by involving two alkali cations.This merit,accompanied by extremely small anisotropy of the thermal expansion of crystal CLGS(0.05)enhances the LIDT(51.0 MW cm^(2))of 4.5 times that of benchmark AgGaS_(2)(11.3 MW cm^(2))at 1064 nm with the pulse width of 10 ns.Phase CLGS adopts a diamond-like anionic framework in which all tetrahedra are arranged in a highly oriented manner,providing a critical contribution to modest second-harmonic generation 0.7 times that of AgGaS_(2) with a phase-matchable behaviour at the 1910 nm laser.These attributes,along with broad transmittance,warrant the further exploration of potential IR NLO chalcogenides containing multiple alkali cations.展开更多
The targeted synthesis of ultraviolet(UV)nonlinear optical(NLO)materials with strong second-harmonic generation(SHG)activity and wide transparency window remains a formidable challenge.Herein,a prospective rare-earth ...The targeted synthesis of ultraviolet(UV)nonlinear optical(NLO)materials with strong second-harmonic generation(SHG)activity and wide transparency window remains a formidable challenge.Herein,a prospective rare-earth borate UV NLO crystal,KNa_(2)La_(2)(BO_(3))_(3),was extracted by spontaneous crystallization using a flux method.展开更多
基金This work was supported by the National Natural Science Foundation of China(No.U2230203)the Fundamental Research Funds for the Central Universities.
文摘Polarization-dependent second harmonic generation is a widely utilized technique for characterizing symmetry.However,in collinear reflective geometry,the essential beam-splitting device significantly influences both the polarization state of the fundamental and harmonic beams,thereby affecting the accuracy of the obtained second-order nonlinear susceptibility.Here,we propose a data correction method to solve this problem to obtain accurate secondorder nonlinear susceptibility.The feasibility and generality of the method are demonstrated through theoretical and experimental validation.
基金supported by the National Natural Science Foun-dation of China(No.12274339).
文摘Second harmonic generation(SHG),a fundamental and widely-studied phenomenon in nonlinear optics,has attracted significant attention for its ability to convert fundamental frequencies into their second harmonics.While the dominant SHG research has been focused on the optical and infrared regimes,its investigation in the microwave range presents challenges due to the requirements of materials with higher nonlinear coefficients and high-power microwave sources.Here,we provide an overview of methods together with underlying mechanisms for SHG in microwave frequencies,and discuss prospects and insights into the future developments of SHG-based technologies.The discussions on both numerical analyses and experimental studies will offer guidance for further SHG research and communication advancements in microwave regime.
基金performed at the Chinese Academy of Science Terahertz Science Centersupported by the National Natural Science Foundation of China(Grant No.61988102)
文摘We investigate high-order harmonic generations(HHGs)under comparison of Weyl cones in two types.Due to the hyperboloidal electron pocket structure,strong noncentrosymmetrical generations in high orders are observed around a single type-ⅡWeyl point,especially at zero frequency.Such a remarkable DC signal is proved to have attributions from the intraband transition after spectral decomposition.Under weak pulse electric field,the linear optical response of a nontilted Weyl cone is consistent with the Kubo theory.With extensive numerical simulations,we conclude that the non-zero chemical potential can enhance the even-order generations,from the slightly tilted system to the over-tilted systems.In consideration of dynamical symmetries,type-Ⅰand type-ⅡWeyl cones also show different selective responses under the circularly polarized light.Finally,using a more realistic model containing two pairs of Weyl points,we demonstrate that paired Weyl points with opposite chirality can suppress the overall even-order generations.
基金supported by the National Natural Science Foundation of China(No.22275184)the Fujian Science&Technology Innovation Laboratory for Optoelectronic Information of China(2021ZR104).
文摘The development of nonlinear optical(NLO)crystals with excellent performance has been the goal of numerous researchers.Herein,iodide has been successfully introduced into lead 2,6-pyridinedicarboxylates to rationally synthesize a series of new stable NLO crystals,APb_(2)(C_(7)H_(3)NO_(4))_(2)I(A=K,Rb,Cs),via a mild mix-solvothermal method.
基金supported by the Natural Science Foundation of Tianjin(Grant No.20JCJQJC00060 and 19JCZDJC38200)the National Natural Science Foundation of China(Grant No.22071179,51802217,51972230,61835014,and 51890865)+1 种基金Tianjin Science and technology Plan Program(Grant No.19ZYPTJC00070)National Key R&D Program of China(Grant No.2016YFB0402103).
文摘Ultraviolet nonlinear optical (UV NLO) crystals are the key and basic materials for solid-state lasers.Phosphates as UV NLO crystals are limited in practical applications due to their weak second-harmonic generation (SHG) response.In this work,two non-centrosymmetric pyro-phosphates of K_(3)SrBi(P_(2)O_(7))_(2) and Rb_(3)SrBi(P_(2)O_(7))_(2) have been synthesized by a high-temperature solution method.Systematic property measurements show that they both have short UV cut-off edges (∼240 nm) and large SHG responses (4 × KDP for K_(3)SrBi(P_(2)O_(7))_(2) and 2.1 × KDP for Rb_(3)SrBi(P_(2)O_(7))_(2)).Thus,they are both promising UV NLO candidates.In particular,K_(3)SrBi(P_(2)O_(7))_(2) shows the strongest SHG response in the family of A_(3)BBi(P_(2)O_(7))_(2) (A = K,Rb,B = Sr;A = Rb,Cs,B = Ba,Pb),which is about twice higher than that of isomorphic Rb_(3)SrBi(P_(2)O_(7))_(2).The study of the structure–property relationship shows that the synergistic effect of P_(2)O_(7) dimers and BiO6 polyhedra is the main contribution to their excellent NLO properties.And better orientations of P_(2)O_(7) dimers and larger distortion of BiO6 units play important roles in enhancing the SHG response of K_(3)SrBi(P_(2)O_(7))_(2).
基金supported by the National Natural Science Foundation of China(Grant No 21975255,51890862,U1605245,and 51425205)the National Key Research and Development Plan of Ministry of Science and Technology(Grant No 2016YFB0402104)+2 种基金the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No XDB20000000)the NSF of Fujian Province(2019J01020758)the Youth Innovation Promotion Association CAS(303).
文摘A new mixed alkali hydro-isocyanurate,RbNa(HC_(3)N_(3)O_(3))·2H_(2)O,with the noncentrosymmetric space group Pna21(No.33),has been successfully grown by a hydrothermal method.The structure can be described as 2D wavy[Na(HC_(3)N_(3)O_(3))O_(4)]∞layers separated by Rb atoms.The UV-vis diffuse reflection measurement revealed that RbNa(HC_(3)N_(3)O_(3))·2H_(2)O has a large band gap of 5.10 eV,corresponding to the UV cutoff edge of 241 nm.The polarizing microscope measurement of a micron-sized single crystal shows that RbNa(HC_(3)N_(3)O_(3))·2H_(2)O has a large birefringence of 0.194.The powder SHG measurement indicated that RbNa(HC_(3)N_(3)O_(3))·2H_(2)O exhibits a strong SHG effect that is 5.3 times that of KH_(2)PO_(4)(KDP)and can realize phase-matching in the visible and UV region.Moreover,the differences in the SHG responses between RbNa(HC_(3)N_(3)O_(3))·2H_(2)O and two isostructural compounds have been investigated,which depend heavily on the structural modulation of the(HC_(3)N_(3)O_(3))2-group by cations.Meanwhile,the electronic structures and optical properties were well analyzed using DFT methods.
基金supported by the National Natural Science Foundation of China(Grant No.22222510,21975255 and 21921001)the Foundation of Fujian Science&Technology Innovation Laboratory(2021ZR202)the Youth Innovation Promotion Association CAS(2019303).
文摘It is generally considered difficult for traditional sulfates to exhibit strong second harmonic generation(SHG)responses and large birefringence values because SO_(4)groups are nonpolar tetrahedral structures.However,by theoretical calculations,we found that polar tetrahedral S_(2)O_(3)shows great improvements in anisotropy and second order polarizability compared to SO_(4)while the wide band gap can be preserved.
基金supported by the National Natural Science Foundation of China(no.51432006)the Ministry of Education of China for the Changjiang Innovation Research Team(no.IRT13R24)+1 种基金the Ministry of Education and the State Administration of Foreign Experts Affairs for the 111 Project(no.B13025)the Innovation Program of Shanghai Municipal Education Commission.M.G.H.and C.Z.thank the Australian Research Council for support(DP170100411).
文摘Infrared(IR)nonlinear optical(NLO)materials have attracted tremendous interest for civil and military applications,but it remains a great contemporary challenge to develop high-effciency NLO crystals that possess suffciently high second-harmonic generation(SHG)effciencies coupled to wide transparency ranges and high laser damage thresholds.A series of new hydrous rare-earth iodates RE(IO_(3))_(3)·(H_(2)O)(RE=Y 1,Eu 2)and La_(2)(IO_(3))_(6)(H_(2)O)(3)have been synthesized through facile hydrothermal methods.1 and 2 are isostructural,crystallizing in the polar space group P21,while 3 crystallizes in the polar space group Pc.1-3 feature three-dimensional(3D)frameworks composed of alternately connected corner-shared dis torted[REO_(x)]polyhedra(RE=Y,Eu,and La;x=8,9)and[IO_(3)]^(−)groups.Optical studies showed that 1–3 exhibit good NLO properties,including strong SHG intensities(3.0×(1),4.5×(2),and 1.5×KH_(2)PO_(4)(3)),large band gaps(4.12(1),4.36(2),and 4.24 eV(3),with 2 possessing the largest band gap among the known SHG-active rare-earth-based iodates,high laser damage thresholds(LDT)(53×(1),43×(2),and 44×AgGaS_(2)(3)),and wide transparency ranges(ca.3.0–11.3μm)in the mid-IR region covering two criti cal IR transparency windows;1–3 are therefore potential candidate NLO materials.Density functional theory calculations on 1–3 confirm that their strong SHG responses and large band gaps are mainly derived from the synergistic effect of[IO_(3)]^(−)groups and rare-earth oxide polyhedra[REOx]in their 3D frameworks.We conclude that the introduction of rare-earth cations with moderate electropositivity into iodates may optimize the balance between SHG effciency and optical band gaps,the key requirement for high-performance NLO materials for practical applications.
基金support by the National Natural Science Foundation of China(21771159,22071212)the Qinglan Project of Jiangsu Province of China,the Youth Innovation Promotion Association of Chinese Academy of Sciences(2022303)the Foundation of Excellent Doctoral Dissertation of Yangzhou University.
文摘The exploration of new infrared(IR)nonlinear optical(NLO)crystals with large second-harmonic generation(SHG)responses and high laser-induced damage thresholds(LIDTs)concurrently is urgently needed and challenging.Herein,the first-type of noncentrosymmetric(NCS)alkali metal Ag-based thiophosphates KAg_(2)PS_(4)(1)and(Na_(0.30)K_(0.70))Ag_(2)PS_(4)(2)were successfully synthesized using a high-temperature solid-state method.
基金supported by the National Natural Science Foundation of China(21921001,21827813,92161125,22075283,and 22175172)the Youth Innovation Promotion Association of Chinese Academy of Sciences(2021300)Fujian Science&Technology Innovation Laboratory for Optoelectronic Information of China(2020ZZ108,2021ZR205).
文摘Infrared(IR)nonlinear optical(NLO)materials with simultaneous strong NLO coefficient and high laserinduced damaged threshold(LIDT)are the urgently desired optical performance NLO materials in laser application.Here,two different electropositive alkali elements are concurrently incorporated into a tetrahedral GaS_(4) anionic framework,affording the first polar quaternary sulphide CsLiGa_(6)S_(10)(CLGS)with mixed ordered alkali cations through the solid-state method.CLGS displays a wide band gap(3.25 eV)originating from the GaS_(4) anionic framework and assistant of the‘dimensional reduction’effect by involving two alkali cations.This merit,accompanied by extremely small anisotropy of the thermal expansion of crystal CLGS(0.05)enhances the LIDT(51.0 MW cm^(2))of 4.5 times that of benchmark AgGaS_(2)(11.3 MW cm^(2))at 1064 nm with the pulse width of 10 ns.Phase CLGS adopts a diamond-like anionic framework in which all tetrahedra are arranged in a highly oriented manner,providing a critical contribution to modest second-harmonic generation 0.7 times that of AgGaS_(2) with a phase-matchable behaviour at the 1910 nm laser.These attributes,along with broad transmittance,warrant the further exploration of potential IR NLO chalcogenides containing multiple alkali cations.
基金supported by the National Key R&D Program of China(2021YFA0717800)the Natural Science Foundation of China(Grant No.52002273,52002220,61835014 and 51890864).
文摘The targeted synthesis of ultraviolet(UV)nonlinear optical(NLO)materials with strong second-harmonic generation(SHG)activity and wide transparency window remains a formidable challenge.Herein,a prospective rare-earth borate UV NLO crystal,KNa_(2)La_(2)(BO_(3))_(3),was extracted by spontaneous crystallization using a flux method.
