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Distributed feedback organic lasing in photonic crystals

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Frontiers of Optoelectronics 2020年第1期13卷 18-34页

作者： Yulan FU Tianrui ZHAI Institute of Information Photonics Technology College of Applied SciencesBeijing University of TechnologyBeijing 100124China

Considerable research efforts have been devoted to the investigation of distributed feedback(DFB)organic lasing in photonic crystals in recent decades.It is still a big challenge to realize DFB lasing in complex photonic crystals.This review discusses the recent progress on the DFB organic laser based on one-,two-,and three-dimensional photonic crystals.The photophysics of gain materials and the fabrication of laser cavities are also introduced.At last,future development trends of the lasers are prospected.

关键词： photonic crystals microcavity lasers distributed feedback(DFB)

Topological photonic crystals:a review

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Frontiers of Optoelectronics 2020年第1期13卷 50-72页

作者： Hongfei WANG Samit Kumar GUPTA Biye XIE Minghui LU National Laboratory of Solid State Microstructures and Department of Materials Science and Engineering Nanjing UniversityNanjing 210093China Collaborative Innovation Center of Advanced Microstructures Nanjing UniversityNanjing 210093China Jiangsu Key Laboratory of Artificial Functional Materials Nanjing UniversityNanjing 210093China

The field of topological photonic crystals has attracted growing interest since the inception of optical analog of quantum Hall effect proposed in 2008.Photonic band structures embraced topological phases of matter,have spawned a novel platform for studying topological phase transitions and designing topological optical devices.Here,we present a brief review of topological photonic crystals based on different material platforms,including all-dielectric systems,metallic materials,optical resonators,coupled waveguide systems,and other platforms.Furthermore,this review summarizes recent progress on topological photonic crystals,such as higherorder topological photonic crystals,non-Hermitian photonic crystals,and nonlinear photonic crystals.These studies indicate that topological photonic crystals as versatile platforms have enormous potential applications in maneuvering the flow of light.

关键词： topological photonic crystals topological phase transitions non-Hermitian photonics higher-order topological photonic crystals

Dynamically reconfigurable topological edge state in phase change photonic crystals

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Science Bulletin 2019年第12期64卷 814-822页

作者： Tun Cao Linhan Fang Ying Cao Nan Li Zhiyou Fan Zhiguo Tao School of Optoelectronic Engineering and Instrumentation Science Dalian University of TechnologyDalian 116024China China North Vehicle Research Institute Beijing 100072China

The observation of topological edge states(TESs) revolutionized our understanding of scattering and propagation of electromagnetic(EM) waves. Supported by topological robustness, the TES at the interface between trivial and non-trivial insulators was not reflected from the structural disorders and imperfections. Recently topological photonic crystals(PhCs) were demonstrated to obtain remarkable one-way propagation of the TES, having the advantages of lossless propagation, dense integration, and high fabrication tolerance over conventional PhCs. Nevertheless, the lack of reversible switching of TES possesses significant limitations in helicity/spin filtering and tunable photonic devices. We proposed a topological PhC based on a prototypical phase-change material, Ge2 Sb2 Te5(GST225) to solve the problem. We find that at a particular frequency, the TES within the structure can be reversibly switched between "on"and "off" by transiting the GST225 structural state between amorphous and crystalline. Moreover, the topology of the PhC was maintained since the tuning of TES was achieved by varying the refractive index of GST225 instead of the structural geometry. This provides a continuous change of the spectral position of the photonic bandgap and TES by gradually crystallising the GST225. We show that the phase change of GST225 from amorphous to crystalline and vice versa can be engineered in nanoseconds. Our proof of concept may offer a platform for dynamically tuning the TESs that might otherwise be challenging to attain in photonic systems. We expect it to have potential applications for photonic devices in topological optical circuits and scatter-free one-way light propagation.

关键词： Phase change materials Photonic crystals Topological edge states Tunability Reconfigurability

Striking 2D materials: exfoliation of molecular crystals

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Science China Chemistry 2022年第6期65卷 1005-1006页

作者： Yin Zhang Shengqian Ma Department of Chemistry University of North TexasDentonTX76201USA

Ultrathin nanosheets, which are often prepared from bulk crystals by exfoliating, represent an intriguing type of twodimensional (2D) materials with mechanical, electronic,optical, and thermal properties that are distinct from their pristine bulk crystals. They are promising in various applications, including (opto)electronics, chemical sensing, catalysis, and separation, because of their unique properties and high surface area. Previously, the operationally simple exfoliation method is only applicable to bulk crystals with weak interactions between the layers.

关键词： crystals separation catalysis

Equilibrium mercury and lead isotope fractionation caused by nuclear volume effects in crystals

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Acta Geochimica 2021年第2期40卷 150-162页

作者： Sha Yang Yun Liu Department of Geological Engineering Qinghai University.Xining 810016China State Key Laboratory of Ore Deposit Geochemistry Institute of GeochemistryChinese Academy of SciencesGuiyang 550081China International Center for Planetary Science College of Earth SciencesChengdu University of TechnologyChengdu 610059China CAS Center for Excellence in Comparative Planetology Hefei 230026China

To investigate equilibrium mercury(Hg)and lead(Pb)isotope fractionation caused by the nuclear volume effect(NVE)in crystals,the electron densities at nuclei(i.e.,|Ψ(0)|2)for Hg-or Pb-bearing crystalline compounds were investigated by using the relativistic spin orbit zeroth-order regular approximation(ZORA)method with a three-dimensional periodic boundary condition based on the density functional theory(DFT).Many isotope fractionation factors of crystalline compounds are provided for the first time.Our results show,even at1000℃,NVE-driven Hg and Pb isotope fractionation are meaningfully large,i.e.,range from 0.12‰to 0.49‰(202Hg/^(198)Hg),from-0.20‰to 0.17‰(208Pb/^(206)Pb)and from-0.08‰to 0.06‰(207Pb/^(206) Pb)relative to Hg0 vapor and Pb0 vapor,respectively.Specifically,the fractionations range from-0.06‰to-0.20‰(208Pb/^(206)Pb)and from-0.02‰to-0.08‰(207Pb/^(206)Pb)for Pb2+-bearing species,from 0.10‰to 0.17‰(208Pb/^(206)Pb)and from 0.04‰to 0.06‰(207Pb/^(206)Pb)for Pb4+-bearing species in crystals.All calculated Hg-bearing species in crystals will enrich heavier isotope(202Hg)relative to Hg0 vapor.Meanwhile,Pb4+-bearing species enrich heavier Pb isotopes(208Pb and 207Pb)than Pb^(2+)-bearing species in crystals,which the enrichment can be up to 0.37‰(208-Pb/^(206)Pb)and 0.14‰(207Pb/^(206)Pb)at 1000℃,due to their NVEs are in opposite directions.The NVE-driven MIFs of Hg isotopes,which are compared to the Hg202-Hg198baseline,are up to-0.158‰(ΔNV199Hg),-0.024‰(ΔNV200Hg)and-0.094‰(ΔNV201Hg)relative to Hg0 vapor at5000 C.For all studied Hg-bearing species in crystals,the MIFs of two odd-mass isotopes(i.e.,ΔNV199Hg andΔNV201Hg)will be changed proportionally and their ratio(i.e.,ΔNV199Hg/ΔNV201Hg)will be a constant 1.67.The NVE can also cause mass-independent fractionations for 207Pb and 204 Pb compared to the baseline of 208Pb and 206Pb.The largest NVEdriven MIFs are 0.043‰(ΔNV207Pb)and-0.040‰(ΔNV204Pb)among all the studied species relative to Pb0 vapor at 5000 C.The magnitudes of odd-mass isotope MIF(ΔNV207Pb)and even-m

关键词： Mercury and lead isotopes crystals Nuclear volume effect DFT relativistic effect calculations

Rapid Growth of Halide Perovskite Single crystals:From Methods to Optimization Control

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Chinese Journal of Chemistry 2019年第6期37卷 616-629页

作者： Yu-Ling Wang Shuai Chang Xiao-Mei Chen Yan-Dong Ren Li-Fu Shi Yong-Hao Liu Hai-Zheng Zhong School of Mechatronics Engineering Daqing Normal UniversityXibin Xi RoadRanghulu DistrictDaqingHeilongjiang 163712China Beijing Key Laboratory of Nanophotonics and Ultrafine Optoelectronic Systems School of Materials Science&EngineeringBeijing Institute of TechnologyZhongguancun South StreetHaidian DistrictBeijing 100081China

Metal halide perovskites are emerging as new generation optoelectronic materials due to their high carrier mobility, long carrier diffusion length and large light absorption coefficient, which have broad applications in solar cell, light-emitting diode, laser, photodetector and transistors. Perovskite single crystal is an ideal platform for discerning the intrinsic properties of these materials. In some cases, perovskite single crystals are better candidates to gain high performance optoelectronics. However, the growth of perovskite single crystals is time and cost consuming, which has an obvious disadvantage for device exploration. Therefore, fast growth technique is highly desirable in not only promoting the use of perovskites in commercial applications but also facilitating deep physical investigation of the materials. In this review, we summarize thoroughly the development of fast growth of the halide perovskites single crystal. Specifically, we highlight the progress of rapid growth techniques with emphasis on the optimization control.

关键词： crystal growth semiconductors synthetic methods metal halide perovskite single crystals rapid growth

Sine-Gordon Solitons and Breathers in Rod-like Magnetic Liquid crystals under External Magnetic Field

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Communications in Theoretical Physics 2018年第12期69卷 759-764页

作者：李妍鲁小波侯春风 Department of Physics Harbin Institute of Technology Department of Physics Science and Technology Heilongjiang University

To study the nonlinear phenomena in rod-like magnetic liquid crystals(RMLCs), this paper establishes the dynamic model of molecular motion when giving a twisting disturbance to the molecules under external magnetic field.We find the twist of the molecules under magnetic field can be propagated in the form of a traveling wave. The dynamic equation of the molecular twisting we derived satisfies the form of Sine-Gordon equation. We obtain two solutions of the Sine-Gordon equation by theoretical calculation: the kink and anti-kink solitons and breathers. The characteristics of those solitons and breathers are discussed.

关键词： rod-like magnetic liquid crystals Sine-Gordon equation kink and anti-kink solitons breathers

Optical spectra of Eu^(2+) ion doped KMgF_3 single crystals grown by Bridgman method

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Optoelectronics Letters 2019年第1期15卷 26-30页

作者：施旭栋夏海平胡建旭章践立朱永胜陈宝玖 Key Laboratory of Photo-electronic Materials Ningbo University College of Physics and Electronic Engineering College of Chemistry and Pharmaceutical Engineering Nanyang Normal University Department of Physics Dalian Maritime University

High-quality KMgF_3 single crystal containing 0.5 mol% europium (Eu) was prepared by an improved Bridgman method.X-ray diffraction(XRD),photoluminescence spectra and fluorescence lifetime were measured.The results indicate the reduction of Eu^(3+)to Eu^(2+)in the KMgF_3 single crystal.Under the excitation of 259 nm,370 nm and 394 nm,the sample has two distinct emissions of Eu^(2+):4f^7→4f^7(～363 nm)and 4f^65d^1→4f^7(～440 nm).The substitution site for Eu ion is confirmed.The optical property investigation result shows that the Eu^(2+)doped KMgF_3 single crystal may be used as potential laser media and related materials for optical devices.

关键词： crystals Bridgman method investigation

Investigation into the room temperature creep-deformation of potassium dihydrogen phosphate crystals using nanoindentation

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Advances in Manufacturing 2018年第4期6卷 376-383页

作者： Yong Zhang Ning Hou Liang-Chi Zhang School of Mechatronics Engineering The Harbin Institute of Technology Harbin 150001 People's Republic of China Ministry of Education Key Laboratory of Micro-systems and Micro-structures Manufacturing The Harbin Institute of Technology Harbin 150001 People's Republic of China Laboratory for Precision and Nano Processing Tech no logies. School of Mechanical and Manufacturing Engineering The University of New South Wales Sydney NSW 2052 Australia

It has been a tremendous challenge to manu facture damage-free and smooth surfaces of potassium dihydrogen phosphate (KDP) crystals to meet the require ments of high-energy laser systems. The intrinsic issue is whether a KDP crystal can be plastically deformed so that the material can be removed in a ductile mode during the machining of KDP. This study investigates the room tem perature creep-deformation of KDP crystals with the aid of nanoindentation. A stress analysis was carried out to identify the creep mechanism. The results showed that KDP crystals could be plastically deformed at the nanoscale. Dislocation motion is responsible for creep-deformation. Both creep rate and creep depth decrease with decrease in peak force and loading rate. Dislocation nucleation and propagation bring about pop-ins in the load displacement curves during nanoindentation.

关键词： Potassium dihydrogen phosphate (KDP) crystals Creep-deformation Stress Dislocation