Nonlinear holography has recently emerged as a novel tool to reconstruct the encoded information at a new wavelength,which has important applications in optical display and optical encryption.However,this scheme still...Nonlinear holography has recently emerged as a novel tool to reconstruct the encoded information at a new wavelength,which has important applications in optical display and optical encryption.However,this scheme still struggles with low conversion efficiency and ineffective multiplexing.In this work,we demonstrate a quasi-phasematching(QPM)-division multiplexing holography in a three-dimensional(3D)nonlinear photonic crystal(NPC).3D NPC works as a nonlinear hologram,in which multiple images are distributed into different Ewald spheres in reciprocal space.The reciprocal vectors locating in a given Ewald sphere are capable of fulfilling the complete QPM conditions for the high-efficiency reconstruction of the target image at the second-harmonic(SH)wave.One can easily switch the reconstructed SH images by changing the QPM condition.The multiplexing capacity is scalable with the period number of 3D NPC.Our work provides a promising strategy to achieve highly efficient nonlinear multiplexing holography for high-security and high-density storage of optical information.展开更多
N-Heterocyclic nitrogen Lewis acids are important in synthetic chemistry.Stable cyclic(amino)(aryl)nitrenium cations,cyc-1^(+)-cyc-3^(+),were synthesized by chemical oxidation of aryl azo compounds with different subs...N-Heterocyclic nitrogen Lewis acids are important in synthetic chemistry.Stable cyclic(amino)(aryl)nitrenium cations,cyc-1^(+)-cyc-3^(+),were synthesized by chemical oxidation of aryl azo compounds with different substituents,H and I,at the para positions of the phenyl group.The excited triplet states of cyc-1^(+)-cyc-3^(+) abstract H-atoms step by step to generate radical intermediates cyc-1H^(*+-)cyc-3H^(*+)traced by EPR spectroscopy and products cyc-1H^(2+)-cyc-3H^(2+) characterized by single crystal X-ray diffraction.The Lewis acidity of species cyc-1^(+)-cyc-3^(+) are remote substituent-dependent.Cyc-2^(+)-cyc-3^(+) have much higher acidity than those previously reported congeners based on energies of LUMOs.The electrophilicity enables them to form Lewis adducts with neutral Lewis base Me_(3)P,and to gain one-electron to produce neutral radicals cyc-1^(*)-cyc-3^(*).展开更多
基金the National Key R&D Program of China(2017YFA0303703,2018YFB1105400,and 2016YFA0302500)the National Natural Science Foundation of China(NSFC)(91950206,11874213,51875544,91963127,51675503,and 62005262)+5 种基金National Key Scientific Instrument and Equipment Development Project(61927814)Youth Innovation Promotion Association of the Chinese Academy of Sciences(2017495)Foundation of Equipment Development Department(6220914010901)Anhui Province Science and Technology Major Project(201903a05020005)Fundamental Research Funds for the Central Universities(021314380105)The China Postdoctoral Science Foundation(2020M671838 and 2021T14069)。
文摘Nonlinear holography has recently emerged as a novel tool to reconstruct the encoded information at a new wavelength,which has important applications in optical display and optical encryption.However,this scheme still struggles with low conversion efficiency and ineffective multiplexing.In this work,we demonstrate a quasi-phasematching(QPM)-division multiplexing holography in a three-dimensional(3D)nonlinear photonic crystal(NPC).3D NPC works as a nonlinear hologram,in which multiple images are distributed into different Ewald spheres in reciprocal space.The reciprocal vectors locating in a given Ewald sphere are capable of fulfilling the complete QPM conditions for the high-efficiency reconstruction of the target image at the second-harmonic(SH)wave.One can easily switch the reconstructed SH images by changing the QPM condition.The multiplexing capacity is scalable with the period number of 3D NPC.Our work provides a promising strategy to achieve highly efficient nonlinear multiplexing holography for high-security and high-density storage of optical information.
基金the National Key R&D Program of China(Grants 2016YFA0300404 and 2018YFA0306004,X.W.)the National Natural Science Foundation of China(Grants 21525102 and 21690062,X.W.,and 21901005,W.W.)+1 种基金the Natural Science Foundation of Anhui Province(Grant 1908085QB48,W W.)the China Postdoctoral Science Foundation(Grant 2019M651771,W.W.).
文摘N-Heterocyclic nitrogen Lewis acids are important in synthetic chemistry.Stable cyclic(amino)(aryl)nitrenium cations,cyc-1^(+)-cyc-3^(+),were synthesized by chemical oxidation of aryl azo compounds with different substituents,H and I,at the para positions of the phenyl group.The excited triplet states of cyc-1^(+)-cyc-3^(+) abstract H-atoms step by step to generate radical intermediates cyc-1H^(*+-)cyc-3H^(*+)traced by EPR spectroscopy and products cyc-1H^(2+)-cyc-3H^(2+) characterized by single crystal X-ray diffraction.The Lewis acidity of species cyc-1^(+)-cyc-3^(+) are remote substituent-dependent.Cyc-2^(+)-cyc-3^(+) have much higher acidity than those previously reported congeners based on energies of LUMOs.The electrophilicity enables them to form Lewis adducts with neutral Lewis base Me_(3)P,and to gain one-electron to produce neutral radicals cyc-1^(*)-cyc-3^(*).
