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Temporal electric field of a helium plasma jet by electric field induced second harmonic(E-FISH)method 被引量:2
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作者 李旭 晋绍珲 +3 位作者 宋珂 聂兰兰 刘大伟 卢新培 《Plasma Science and Technology》 SCIE EI CAS CSCD 2023年第1期43-52,共10页
Electric field is an important parameter of plasma,which is related to electron temperature,electron density,excited species density,and so on.In this work,the electric field of an atmospheric pressure plasma jet is d... Electric field is an important parameter of plasma,which is related to electron temperature,electron density,excited species density,and so on.In this work,the electric field of an atmospheric pressure plasma jet is diagnosed by the electric field induced second harmonic(E-FISH)method,and the time-resolved electric field under different conditions is investigated.When positive pulse voltage is applied,the electric field has a peak of about 25 kV cm-1at the rising edge of the voltage pulse.A dark channel is left behind the plasma bullet and the electric field in the dark channel is about 5 kV cm-1.On the other hand,when negative pulse voltage is applied,the electric field has a peak of-16 kV cm-1when the negative voltage is increased to-8 kV.A relatively bright channel is left behind the plasma head and the electric field in this relatively bright channel is about-6 kV cm-1.When the pulse rising time increases from 60 to 200 ns,the peak electric field at both the rising edge and the falling edge of the voltage decreases significantly.When 0.5%of oxygen is added to the main working gas helium,the peak electric field at the rising edge is only about 15 kV cm-1.On the other hand,when 0.5%nitrogen is added,the peak electric field increases especially at the falling edge of the voltage pulse,where it increases reversely from-12 to-16 kV cm-1(the minus sign only represents the direction of electric field). 展开更多
关键词 atmospheric pressure plasma jet electric field electric field induced second harmonic
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Cumulative second-harmonic generation of Lamb waves propagating in a two-layered solid plate 被引量:2
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作者 项延训 邓明晰 《Chinese Physics B》 SCIE EI CAS CSCD 2008年第11期4232-4241,共10页
The physical process of cumulative second-harmonic generation of Lamb waves propagating in a two-layered solid plate is presented by using the second-order perturbation and the technique of nonlinear reflection of aco... The physical process of cumulative second-harmonic generation of Lamb waves propagating in a two-layered solid plate is presented by using the second-order perturbation and the technique of nonlinear reflection of acoustic waves at an interface. In general, the cumulative second-harmonic generation of a dispersive guided wave propagation does not occur. However, the present paper shows that the second-harmonic of Lamb wave propagation arising from the nonlinear interaction of the partial bulk acoustic waves and the restriction of the three boundaries of the solid plates does have a cumulative growth effect if some conditions are satisfied. Through boundary condition and initial condition of excitation, the analytical expression of cumulative second-harmonic of Lamb waves propagation is determined. Numerical results show the cumulative effect of Lamb waves on second-harmonic field patterns. 展开更多
关键词 Lamb waves second harmonics cumulative effect layered plates
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Second Harmonic Generation of Lamb Wave in Numerical Perspective 被引量:2
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作者 朱武军 邓明晰 +2 位作者 项延训 轩福贞 刘长军 《Chinese Physics Letters》 SCIE CAS CSCD 2016年第10期71-74,共4页
The influences of phase and group velocity matching on cumulative second harmonic generation of Lamb waves are investigated in numerical perspective. Finite element simulations of nonlinear Lamb wave propagation are p... The influences of phase and group velocity matching on cumulative second harmonic generation of Lamb waves are investigated in numerical perspective. Finite element simulations of nonlinear Lamb wave propagation are performed for Lamb wave mode pairs with exact and approximate phase velocity matching, with and without group velocity matching, respectively. The evolution of time-domain second harmonic Lamb waves is analyzed with the propagation distance. The amplitudes of primary and second harmonic waves are calculated to characterize the acoustic nonlinearity. The results verify that phase velocity matching is necessary for generation of the cumulative second harmonic Lamb wave in numerical perspective, while group velocity matching is demonstrated to not be a necessary condition. 展开更多
关键词 of on MODE second harmonic Generation of Lamb Wave in Numerical Perspective in IS for PAIR
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A 0.33-THz second-harmonic frequency-tunable gyrotron 被引量:1
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作者 李铮迪 杜朝海 +2 位作者 戚向波 罗里 刘濮鲲 《Chinese Physics B》 SCIE EI CAS CSCD 2016年第2期585-591,共7页
Dynamics of the axial mode transition process in a 0.33-THz second-harmonic gyrotron is investigated to reveal the physical mechanism of realizing broadband frequency tuning in an open cavity circuit. A new interactio... Dynamics of the axial mode transition process in a 0.33-THz second-harmonic gyrotron is investigated to reveal the physical mechanism of realizing broadband frequency tuning in an open cavity circuit. A new interaction mechanism about propagating waves, featured by wave competition and wave cooperation, is presented and provides a new insight into the beam-wave interaction. The two different features revealed in the two different operation regions of low-order axial modes (LOAMs) and high-order axial modes (HOAMs) respectively determine the characteristic of the overall performance of the device essentially. The device performance is obtained by the simulation based on the time-domain nonlinear theory and shows that using a 12-kV/150-mA electron beam and TE 3,4 mode, the second harmonic gyrotron can generate terahertz radiations with frequency-tuning ranges of about 0.85 GHz and 0.60 GHz via magnetic field and beam voltage tuning, respectively. Additionally, some non-stationary phenomena in the mode startup process are also analyzed. The investiga- tion in this paper presents guidance for future developing high-performance frequency-tunable gyrotrons toward terahertz applications. 展开更多
关键词 GYROTRON mode transition second harmonic frequency tuning TERAHERTZ
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Second harmonic magnetoacoustic responses of magnetic nanoparticles in magnetoacoustic tomography with magnetic induction 被引量:1
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作者 Gepu Guo Ya Gao +3 位作者 Yuzhi Li Qingyu Ma Juan Tu Dong Zhang 《Chinese Physics B》 SCIE EI CAS CSCD 2020年第3期259-264,共6页
Due to the unique magnetic, mechanical and thermal properties, magnetic nanoparticles(MNPs) have comprehensive applications as the contrast and therapeutic agents in biomedical imaging and magnetic hyperthermia. The l... Due to the unique magnetic, mechanical and thermal properties, magnetic nanoparticles(MNPs) have comprehensive applications as the contrast and therapeutic agents in biomedical imaging and magnetic hyperthermia. The linear and nonlinear magnetoacoustic responses determined by the magnetic properties of MNPs have attracted more and more attention in biomedical engineering. By considering the relaxation time of MNPs, we derive the formulae of second harmonic magnetoacoustic responses(2H-MARs) for a cylindrical MNP solution model based on the mechanical oscillations of MNPs in magnetoacoustic tomography with magnetic induction(MAT-MI). It is proved that only the second harmonic magnetoacoustic oscillations can be generated by MNPs under an alternating magnetic excitation. The acoustic pressure of the 2H-MAR is proportional to the square of the magnetic field intensity and exhibits a linear increase with the concentration of MNPs. Numerical simulations of the 2H-MAR are confirmed by the experimental measurements for various magnetic field intensities and solution concentrations using a laser vibrometer. The favorable results demonstrate the feasibility of the harmonic measurements without the fundamental interference of the electromagnetic excitation, and suggest a new harmonic imaging strategy of MAT-MI for MNPs with enhanced spatial resolution and improved signal-to-noise ratio in biomedical applications. 展开更多
关键词 magnetoacoustic TOMOGRAPHY with MAGNETIC INDUCTION second harmonic magnetoacoustic RESPONSES MAGNETIC nanoparticles MAGNETIC force mechanical OSCILLATIONS
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Photoinduced Second Harmonic Generation of Bi_2S_3 Microcrystallite Doped Silica Glass 被引量:2
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作者 Letters Hongbing CHEN and Hai ping XIA Institute of Optoelectric Materials, Ningbo University, Ningbo 315211, China Congshan ZHU and Fuxi GAN Shanghai Institute of Optics & Fine Mechanics, Chinese Academy of Sciences, Shanghai 201800, China 《Journal of Materials Science & Technology》 SCIE EI CAS CSCD 2001年第5期565-566,共1页
Silica glasses doped with Bi2S3 microcystallite was prepared by the sol-gel process. Photoinduced second harmonic generation (SHG) was observed in the glass when it was irradiated with intense 1.06 mum and frequency d... Silica glasses doped with Bi2S3 microcystallite was prepared by the sol-gel process. Photoinduced second harmonic generation (SHG) was observed in the glass when it was irradiated with intense 1.06 mum and frequency doubled laser beams from a mode-locked Nd: YAG laser. It was found that the signal intensity increased with the irradiating time and approached a saturation gradually. The effect may be explained reasonably by the DC field model. 展开更多
关键词 SHG Photoinduced second harmonic Generation of Bi2S3 Microcrystallite Doped Silica Glass BI
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Dual bound states in the continuum enhanced second harmonic generation with transition metal dichalcogenides monolayer 被引量:2
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作者 Peilong Hong Lei Xu Mohsen Rahmani 《Opto-Electronic Advances》 SCIE EI CAS 2022年第7期16-23,共8页
The emergence of two dimensional(2D)materials has opened new possibilities for exhibiting second harmonic genera-tion(SHG)at the nanoscale,due to their remarkable optical response related to stable excitons at room te... The emergence of two dimensional(2D)materials has opened new possibilities for exhibiting second harmonic genera-tion(SHG)at the nanoscale,due to their remarkable optical response related to stable excitons at room temperature.However,the ultimate atomic-scale interaction length with light makes the SHG of Transition Metal Dichalcogenides(TM-Ds)monolayers naturally weak.Here,we propose coupling a monolayer of TMDs with a photonic grating slab that works with doubly resonant bound states in the continuum(BIC).The BIC slabs are designed to exhibit a pair of BICs,reson-ant with both the fundamental wave(FW)and the second harmonic wave(SHW).Firstly,the spatial mode matching can be fulfilled by tilting FW's incident angle.We theoretically demonstrate that this strategy leads to more than four orders of magnitude enhancement of SHG efficiency than a sole monolayer of TMDs,under a pump light intensity of 0.1 GW/cm^(2).Moreover,we demonstrate that patterning the TMDs monolayer can further enhance the spatial overlap coefficient,which leads to an extra three orders of magnitude enhancement of SHG efficiency.These results demonstrate remarkable pos-sibilities for enhancing SHG with nonlinear 2D materials,opening many opportunities for chip-based light sources,nano-lasers,imaging,and biochemical sensing. 展开更多
关键词 second harmonic generation transition metal dichalcogenides bound state in the continuum photonic grating slab
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Disorder Effect on the Transmission of Second Harmonic Waves in One-Dimensional Periodically Poled LiTaO<sub>3</sub> 被引量:1
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作者 Bahrami Omid Baharvand Abdolrahim Bahari Ali 《Journal of Modern Physics》 2019年第4期432-442,共11页
One of the methods for calculating electromagnetic wave dispersion in multi-layer structures is the transfer matrix method. In this paper, we use the transfer matrix method for second harmonic generation in a nonlinea... One of the methods for calculating electromagnetic wave dispersion in multi-layer structures is the transfer matrix method. In this paper, we use the transfer matrix method for second harmonic generation in a nonlinear multilayer structure. The nonlinear photonic crystals investigated in this paper are as one-dimensional multi-layered structures including ferroelectric materials such as LiTaO3. Our goal is to investigate the effect of the disorder on the transmission spectrum of electromagnetic waves. Our results showed that positional disorder has different effects on the transmitting band and the gap band. The disorder in the transmitting band reduces the transmission coefficient of the waves and increases the transmission coefficient of the waves in the gap band. Such work has not yet been done on nonlinear photonic crystals producing the second harmonic. 展开更多
关键词 Transfer Matrix Method Nonlinear Photonic Crystal Random Binary Medium TRANSMISSION Spectra DISORDER EFFECT second harmonic WAVES
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Time-domain analysis of second-harmonic generation of primary Lamb wave propagation in an elastic plate 被引量:2
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作者 邓明晰 项延训 《Chinese Physics B》 SCIE EI CAS CSCD 2010年第11期456-464,共9页
Within the second-order perturbation approximation, this paper investigates the physical process of generation of the time-domain second harmonic by a primary Lamb wave waveform in an elastic plate. The present work i... Within the second-order perturbation approximation, this paper investigates the physical process of generation of the time-domain second harmonic by a primary Lamb wave waveform in an elastic plate. The present work is performed based on the preconditions that the phase velocity matching is satisfied and that the transfer of energy from the primary Lamb wave to the double frequency Lamb wave is not zero. It investigates the influences of the difference between the group velocities of the primary Lamb wave and the double frequency Lamb wave, the propagation distance and the duration of the primary Lamb wave waveform on the envelope shape of the time-domain second harmonic. It finds that the maximum magnitude of the envelope of the second-harmonic waveform can grow within some propagation distance even if the condition of group velocity matching is not satisfied. Our analyses also indicate that the maximum magnitude of the envelope of the second-harmonic waveform is kept constant beyond a specific propagation distance. Furthermore, it concludes that the integration amplitude of the time-domain second-harmonic waveform always grows with propagation distance within the second-order perturbation. The present research yields new physical insight not previously available into the effect of generation of the time-domain second harmonic by propagation of a primary Lamb wave waveform. 展开更多
关键词 Lamb wave second-harmonic generation group velocity matching phase velocity matching
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Enhancement effect of cumulative second-harmonic generation by closed propagation feature of circumferential guided waves 被引量:1
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作者 Guang-Jian Gao Ming-Xi Deng +1 位作者 Ning Hu Yan-Xun Xiang 《Chinese Physics B》 SCIE EI CAS CSCD 2020年第2期301-308,共8页
On the basis of second-order perturbation approximate and modal expansion approach,we investigate the enhancement effect of cumulative second-harmonic generation(SHG)of circumferential guided waves(CGWs)in a circular ... On the basis of second-order perturbation approximate and modal expansion approach,we investigate the enhancement effect of cumulative second-harmonic generation(SHG)of circumferential guided waves(CGWs)in a circular tube,which is inherently induced by the closed propagation feature of CGWs.An appropriate mode pair of primary-and double-frequency CGWs satisfying the phase velocity matching and nonzero energy flux is selected to ensure that the second harmonic generated by primary CGW propagation can accumulate along the circumference.Using a coherent superposition of multi-waves,a model of unidirectional CGW propagation is established for analyzing the enhancement effect of cumulative SHG of primary CGW mode selected.The theoretical analyses and numerical simulations performed directly demonstrate that the second harmonic generated does have a cumulative effect along the circumferential direction and the closed propagation feature of CGWs does enhance the magnitude of cumulative second harmonic generated.Potential applications of the enhancement effect of cumulative SHG of CGWs are considered and discussed.The theoretical analysis and numerical simulation perspective presented here yield an insight previously unavailable into the physical mechanism of the enhancement effect of cumulative SHG by closed propagation feature of CGWs in a circular tube. 展开更多
关键词 CIRCUMFERENTIAL guided wave second-harmonic generation(SHG) enhancement effect of CUMULATIVE SHG CLOSED PROPAGATION FEATURE
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Order-Disorder Transition of Carboxyl Terminated Chains in Polydiacetylenes Vesicles Probed by Second Harmonic Generation and Two-Photon Fluorescence
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作者 Shun-li Chen Xue-feng Zhu +3 位作者 Fang-yuan Yang Xue-cong Pan Wei Gan Qun-hui Yuan 《Chinese Journal of Chemical Physics》 SCIE CAS CSCD 2018年第3期269-276,367,共9页
To understand and control the interfacial properties of polydiacetylenes(PDAs)vesicles withπ-conjugated backbone is very important for their colorimetric sensing of chemical and biological targets.In this work,we ado... To understand and control the interfacial properties of polydiacetylenes(PDAs)vesicles withπ-conjugated backbone is very important for their colorimetric sensing of chemical and biological targets.In this work,we adopted 10,12-pentacosadiynoic acid(PCDA)as the model molecule to prepare PDAs vesicles in aqueous solution with different forms(from monomer to blue-to-purple-to-red phase)by controlling the UV irradiation dose.The variations of the interfacial conformation of PDAs vesicles during chromatic transitions were inspected by the adsorption behaviors of probe molecules(4-(4-diethylaminostyry)-1-methylpyridinium iodide,D289)on vesicle surface with surface-specific second harmonic generation(SHG)and zeta potential measurements.Resonant SHG signal from D289 adsorbed on vesicle surface attenuated sharply,and the adsorption free energy as well as the corresponding two-photon fluorescence signal decreased slightly in chromatic transitions.While,the change in the surface density of the adsorbed D289 molecules for PDAs vesicles with different forms was relatively small as estimated from zeta potential measurements.The attenuation of the SHG intensity was thus attributed to the overall order-disorder transition and the changed orientation of D289 molecules caused by the gradual distortion of carboxyl head group driven by backbone perturbation. 展开更多
关键词 POLYDIACETYLENES VESICLE POLYMERIZATION interfacial adsorption second harmonic generation ORDER-DISORDER transition
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Surface second harmonic generation of chiral molecules using three-coupled-oscillator model
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作者 王晓鸥 李淳飞 李俊庆 《Chinese Physics B》 SCIE EI CAS CSCD 2006年第11期2623-2630,共8页
Based on the three-coupled-oscillator molecular model we proposed, the relation between the second-order susceptibilities of a chiral film and the molecular hyperpolarizabilities is given. The effect of microscopic pa... Based on the three-coupled-oscillator molecular model we proposed, the relation between the second-order susceptibilities of a chiral film and the molecular hyperpolarizabilities is given. The effect of microscopic parameters on the second-order susceptibilities is simulated numerically and the difference between the efficiencies of s-polarized secondharmonic fields induced by the left- and the right-handed circularly-polarized fundamental beams is discussed. The theoretical basis for studying second-order nonlinear optical properties of the chiral molecular media with a tripod-like structure is provided in this paper. 展开更多
关键词 molecular chirality three-coupled-oscillator model second-order susceptibility second harmonic generation
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Study of narrow-band second harmonic generation from a broad-band fundamental pulse
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作者 温静 蒋红兵 +1 位作者 邓勇开 龚旗煌 《Chinese Physics B》 SCIE EI CAS CSCD 2010年第12期318-322,共5页
This paper studies the type-I phase-matched second harmonic generation using 25-fs input laser pulses in a thick BBO crystal. The harmonic signal exhibits a narrow spectrum bandwidth, even though the input pulse has a... This paper studies the type-I phase-matched second harmonic generation using 25-fs input laser pulses in a thick BBO crystal. The harmonic signal exhibits a narrow spectrum bandwidth, even though the input pulse has a broad bandwidth. The energy transfer efficiency and modulation of the fundamental spectrum are investigated. 展开更多
关键词 second harmonic generation cascaded process energy transfer CHIRP
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Properties of periodic multicrystal configurations in walk-off-compensating second harmonic generation of ultrashort pulses
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作者 黄金哲 张留洋 沈涛 《Chinese Physics B》 SCIE EI CAS CSCD 2011年第4期333-344,共12页
This work designs a four-platelet periodic multicrystal configuration in the second harmonic generation of ultra- short pulses as a new walk-off-compensating device. It theoretically investigates a proposed active and... This work designs a four-platelet periodic multicrystal configuration in the second harmonic generation of ultra- short pulses as a new walk-off-compensating device. It theoretically investigates a proposed active and a typical passive compensating scheme with the undepleted-pump approximation. The result shows that the angular and spectral band- widths are proportional to the number of crystal pairs as expected, but the temperature tunability is basically unaltered owing to inter-plate pulse interference. At the same time, an analysis reveals that a misuse of the phase mismatch factor is responsible for a historic controversy about pulse interference. A real design of an ultraviolet second harmonic generation (262.5 nm) is considered in a passive periodic [3-Barium Borate-calcite configuration, where the inter-plate pulse interference is found to form an azimuthal tuning restriction and to lower plate length tolerance. A subsequent numerical simulation with pump depletion is in good accordance with theoretical prediction. 展开更多
关键词 ultrashort pulses second harmonic generation periodic-multicrystal-configurations walk-off-compensating
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Second harmonic generation in inhomogeneous MgO:LiNbO_3 waveguides
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作者 李国辉 蒋海灵 徐信业 《Chinese Physics B》 SCIE EI CAS CSCD 2011年第6期243-246,共4页
A fibre laser at 1111.6 nm is frequency doubled by two inhomogeneous MgO:LiNbO3 waveguides and the output powers of 85 mW and 49 mW at 555.8 nm have been generated with the conversion efficiencies of 47% and 27% resp... A fibre laser at 1111.6 nm is frequency doubled by two inhomogeneous MgO:LiNbO3 waveguides and the output powers of 85 mW and 49 mW at 555.8 nm have been generated with the conversion efficiencies of 47% and 27% respectively. By analysing the second harmonic generation temperature tuning curves, we investigate the influence of the optical inhomogeneities upon the conversion efficiency. The final result shows that the efficiency difference is mainly affected by the optical inhomogeneities in our case. 展开更多
关键词 second harmonic generation optical inhomogeneities WAVEGUIDE
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Tunable Second Harmonic Generation with High Conversion Efficiency in Periodically Poled Lithium Niobate Channel Waveguide
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作者 徐荣辉 陈险峰 +2 位作者 陈玉萍 叶志清 夏宇兴 《Journal of Shanghai Jiaotong university(Science)》 EI 2007年第4期517-519,共3页
The experiment on quasi-phase-matched second harmonic generation (SHG) in a channel waveguide was reported. The waveguide was made by annealed proton exchange in the periodically poled lithium niobate (PPLN) with the ... The experiment on quasi-phase-matched second harmonic generation (SHG) in a channel waveguide was reported. The waveguide was made by annealed proton exchange in the periodically poled lithium niobate (PPLN) with the period of PPLN of 14.9 μm, which was designed for cascading wavelength conversion in dense wavelength division multiplexer optical communications. The measurement results of SHG conversion efficiency as a function of fundamental wavelength at room temperature fit well to sinc^2 shape. The peak of SHG conversion efficiency was 75%·W~ -1 ·cm~ -2 as well as reported. The relationship between the center fundamental wavelength and temperature shows that SHG can be effectively tuned by the temperature in PPLN waveguide. 展开更多
关键词 PERIODICALLY poled LITHIUM niobate(PPLN) second harmonic generation(SHG) waveguide QUASI-PHASE-MATCHING
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Irradiation Effect on Second Harmonic Generation of Dyes Doped KDP Crystals 被引量:1
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作者 P.Kumaresan 《Journal of Electronic Science and Technology of China》 2010年第1期43-45,共3页
Most irradiation studies in the hydrogen bonded ferroelectrics have been concentrated on the transient defects induced by ionising radiation, such as ultraviolet (UV) light, where the defects are closely related to ... Most irradiation studies in the hydrogen bonded ferroelectrics have been concentrated on the transient defects induced by ionising radiation, such as ultraviolet (UV) light, where the defects are closely related to the optical properties. But heavy ion beam irradiation effects have rarely been studied. The structural, optical, and non-linear optical properties of the doped crystals were analyzed with the characterization studies, such as powder XRD, UV-Visible and second harmonic generation (SHG) measurements, respectively. The results for doped KDP crystal were compared with the results of the pure KDP crystals. The experiment results showed that Li^3+ irradiation leads to the development of a well-defined surface H peak in dye doped KDP crystals. The stability of KDP single crystal was improved by doping organic dyes. The nano-islands of dye in KDP were likely to be dissolved and enhance the non-linear optical properties of these materials. 展开更多
关键词 Irradiation effect KDP crystals organic dye second harmonic generation (SHG).
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Second harmonic generation of metal nanoparticles under tightly focused illumination
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作者 孙经纬 王湘晖 +2 位作者 常胜江 曾明 张娜 《Chinese Physics B》 SCIE EI CAS CSCD 2016年第3期403-407,共5页
The near-field and far-field second harmonic (SH) responses of a metal spherical nanoparticle placed in the focal region of a highly focused beam are investigated by using the calculation model based on three-dimens... The near-field and far-field second harmonic (SH) responses of a metal spherical nanoparticle placed in the focal region of a highly focused beam are investigated by using the calculation model based on three-dimensional finite-difference time-domain (FDTD) method. The results show that off-axis backward-propagating SH response can be reinforced by tightly focusing, due to the increase of the relative magnitude of the longitudinal field component and the phase shift along the propagation direction. 展开更多
关键词 second harmonic generation metal nanoparticles focused field
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Temperature-dependent second harmonic generation process based on an MgO-doped periodically poled lithium niobate waveguide
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作者 沈世奎 杨爱英 +2 位作者 左林 崔建民 孙雨南 《Chinese Physics B》 SCIE EI CAS CSCD 2011年第10期258-261,共4页
The temperature dependency of a 5-mo1% MgO-doped periodically poled lithium niobate waveguide was investi- gated in this paper. We started with the temperature-dependent refractive index equation for the waveguide. Se... The temperature dependency of a 5-mo1% MgO-doped periodically poled lithium niobate waveguide was investi- gated in this paper. We started with the temperature-dependent refractive index equation for the waveguide. Secondly, the temperature dependency of the second harmonic generation effect was experimentally researched under different temperatures and pump powers. The quasi-phase matched wavelengths, efficiency bandwidths and peak efficiencies of the waveguide were measured. The experimental results agreed with theoretical simulations, which are indispensable in the following all-optical sampling studies based on the cascaded second harmonic generation/difference-frequency generation process in the current device. 展开更多
关键词 periodically poled lithium niobate second harmonic generation quasi-phase matching Sellmeier equation
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QM/MM Study of the Second Harmonic Generation and Two-photon Absorption Properties of a Fluorescent Proteins-Dreiklang
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作者 张敏熠 魏婧 +2 位作者 宋金帅 吴鹏 李春森 《Chinese Journal of Structural Chemistry》 SCIE CAS CSCD 2018年第9期1393-1403,共11页
A new reversibly switchable fluorescent protein(RSFP), namely Dreiklang, exhibits prominent feature that the wavelengths for switching and fluorescence are decoupled due to its great different structures between bri... A new reversibly switchable fluorescent protein(RSFP), namely Dreiklang, exhibits prominent feature that the wavelengths for switching and fluorescence are decoupled due to its great different structures between bright and dark states. This feature might also induce some nonlinear optic(NLO) properties changing as switching between two states, which might promote new method of biological science. We employ the QM/MM method to simulate the structures of different states, and study their second harmonic generation(SHG) and two-photon absorption(TPA) properties. And we found different states of Dreiklang have different SHG and TPA responses. The SHG and TPA properties of Dreiklang are correlated to particularly geometrical structures of different states, especially the centrosymmetric or nocentrosymmetric π-stacking structures which are formed by chromophore and beside residue Tyr203, so the SHG and TPA responses could be changed as the light induces switching among different states of Dreiklang. This work would prospectively guide the application of Dreiklang on the NLO technology, and help the development of new RSFP with special NLO function. 展开更多
关键词 fluorescent proteins the second harmonic generation two-photon absorption QM/MM method
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