The density matrix approach has been employed to investigate the opticalnonlinear polarization in a single semiconductor quantum dot(QD). Electron states are considered tobe confined within a quantum dot with infinite...The density matrix approach has been employed to investigate the opticalnonlinear polarization in a single semiconductor quantum dot(QD). Electron states are considered tobe confined within a quantum dot with infinite potential barriers. It is shown, by numericalcalculation, that the third-order nonlinear optical susceptibilities for a typical Si quantum dot isdependent on the quantum size of the quantum dot and the frequency of incident light.展开更多
By use of the Keldysh non-equilibrium Green’s-function methods, the third harmonic susceptibilities of two polyaniline families, PANI-HCl and PANI-H 3PO 4, are calculated [ x (3) ( ω )≈10 -12 esu]. It was found tha...By use of the Keldysh non-equilibrium Green’s-function methods, the third harmonic susceptibilities of two polyaniline families, PANI-HCl and PANI-H 3PO 4, are calculated [ x (3) ( ω )≈10 -12 esu]. It was found that the third harmonic susceptibility of polyaniline strongly depends on the delocalization of the electrons. The refractive indices n ( λ =589 nm) of PANI-HCl and PANI-H 3PO 4 are calculated by use of three common methods (the Lorentz-Lorentz theoretical model, the Gladstone-Dale group contribution and the Vogel group correlation) based on group contributions to molar refraction. The calculated n values are varied from 1.31 to 1.42 for PANI-HCl and 1.36 to 1.45 for PANI-H 3PO 4.展开更多
A perturbative approach is used to study the AC response of nonlinear composite media, which obey a current-field relation of the form with components having nonlinear response at finite frequencies. For a sinusoidal...A perturbative approach is used to study the AC response of nonlinear composite media, which obey a current-field relation of the form with components having nonlinear response at finite frequencies. For a sinusoidal applied field, we extend the local potential in terms of sinusoidal components at fundamental frequency and high-order harmonic frequencies to treat the nonlinear composites. For nonlinear composite media with a low concentrations of spherical inclusions, we give the formulae of the nonlinear effective AC susceptibility at the third harmonic frequency.展开更多
Two novel poly[(3-alkylthiophene-2,5-diyl)-(benzylidenequinomethane-2,5-diyl)s] derivatives, poly[ (3-butylthiophene-2,5-diyl)-( p-N,N-dimethylamino) benzylidenequinomethane-2,5-diyl) ] ( PBTDMABQ) and poly [( 3-octyl...Two novel poly[(3-alkylthiophene-2,5-diyl)-(benzylidenequinomethane-2,5-diyl)s] derivatives, poly[ (3-butylthiophene-2,5-diyl)-( p-N,N-dimethylamino) benzylidenequinomethane-2,5-diyl) ] ( PBTDMABQ) and poly [( 3-octylthiophene2,5-diyl) -(p-N, N-dimethylamino ) benzylidenequinomethane-2, 5-diyl)] (POTDMABQ), were synthesized.The band gaps of the two polymers are calculated as 1. 75 eV for PBTDMABQ and 1. 69 eV for POTDMABQ,respectively. The homogenous films of the two polymers were prepared and their third-ordernonlinear optical properties were studied by the backward degenerate four-wave mixing at 532 nm. Byusing the relative measurement technique, the third-order nonlinear optical susceptibilities ofPBTDMABQ and POTDMABQ are calculated as 5. 62 X 10^(-9) and 1. 22 X 10^(-8) ESU, respectively. It isfound that substituted alky groups have strong effects on the band gap and nonlinear opticalproperties of the two polymers. The relatively big third-order nonlinear optical susceptibilitiesand small band gap of POTDMABQ resulted mainly from the longer alkyl with strong electron-donatingability can enhance the delocation degree of conjugated π electronics.展开更多
On the basis of ZINDO method and according to the sum over states(SOS) expression, the program is devised for the calculation of nonlinear second order optical susceptibilites β ijk and studying how ...On the basis of ZINDO method and according to the sum over states(SOS) expression, the program is devised for the calculation of nonlinear second order optical susceptibilites β ijk and studying how different substituents on the phenyl ring attached to the atom silicon influence on the nonlinear second order optical properties of substituted silane series of molecules. The properties of (CH 3) 3Si? ?has been studied particularly. The effect of the length of silica chains on the calculated values has been studied too. The regularity summarized from the calculated results has been explained micromechanically.展开更多
alculations of the nonlinear second-order optical susceptlbilities(β_(ijk))for sub- stituted tl1iophene derivative;with quinoidlike conformation are reported.These systetems possess small dipole moment;and large diff...alculations of the nonlinear second-order optical susceptlbilities(β_(ijk))for sub- stituted tl1iophene derivative;with quinoidlike conformation are reported.These systetems possess small dipole moment;and large differences between dipole mo- ments of ground and first-excited states.Geometry optimizations of the molecules investigated were carried out using AM 1 method.The calculations were performed using INDO/CI method comboned with a sum-over-states expression for β_(jik). The calculated results sbw that the second-order susceptibility is a function of the na- ture and location of substituents and is larger for disubstituted molecules than monosubstituted molecules. Bipolymeric thiophenemetmne with NH_2/NO_2 groups was calctilated to have a β_μof 79. 920 × 10 ̄(-30) esu. It was found that the NH_2 and NO_2 groups in above disubstituted molecules are pull-pull groups in ground states,but are usual push-pull groups in the first excited states.展开更多
Active metamaterials embedded with nonlinear elements are able to exhibit strong nonlinearity in microwave regime.However, existing S-parameter based parameter retrieval approaches developed for linear metamaterials d...Active metamaterials embedded with nonlinear elements are able to exhibit strong nonlinearity in microwave regime.However, existing S-parameter based parameter retrieval approaches developed for linear metamaterials do not apply in nonlinear cases. In this paper, a retrieval algorithm of high-order susceptibilities for nonlinear metamaterials is derived.Experimental demonstration shows that, by measuring the power level of each harmonic while sweeping the incident power,high-order susceptibilities of a thin-layer nonlinear metamaterial can be effectively retrieved. The proposed approach can be widely used in the research of active metamaterials.展开更多
Considering two beams propagate in semiconductor crystal, this paper discusses the polarization dependence of pump beam-induced intensity attenuation of probe beam due to two-photon absorption (TPA). Numerical calcu...Considering two beams propagate in semiconductor crystal, this paper discusses the polarization dependence of pump beam-induced intensity attenuation of probe beam due to two-photon absorption (TPA). Numerical calculation and experimental measurement demonstrate that TPA coefficient is polarization dependent. For homogeneous materials, probe beam attenuation arises from the imaginary part of diagonal and off-diagonal components of third-order nonlinear susceptibilities.展开更多
We study the colour-locked twin-noisy-field correlation effects in the fifth-order nonlinear susceptibility of ultrafast polarization beats in a cascade four-level system. More importantly, the fifth-order phase-sensi...We study the colour-locked twin-noisy-field correlation effects in the fifth-order nonlinear susceptibility of ultrafast polarization beats in a cascade four-level system. More importantly, the fifth-order phase-sensitive heterodyne detection of ultrafast polarization beats has been exploited. The fifth-order nonlinear optical response can be controlled and modified through the colour-locked correlation of twin noisy fields. Thus, this method with the phase dispersion information is a good way to measure the real and imaginary parts of the fifth-order nonlinear susceptibility.展开更多
Ca_(12)Al_(14)O_(33)(C12A7)and Y_(0.02)Ca_(11.98)Al_(14)O_(33)(Y-C12A7)single crystals were grown by using the traveling-solvent floating zone(TSFZ)method.The temperature was increased to avoid the bubbles and cracks ...Ca_(12)Al_(14)O_(33)(C12A7)and Y_(0.02)Ca_(11.98)Al_(14)O_(33)(Y-C12A7)single crystals were grown by using the traveling-solvent floating zone(TSFZ)method.The temperature was increased to avoid the bubbles and cracks which may be formed during the preparation of the ingot material.We have started with the flux higher than the normal to avoid the bubbles and make good treatment for the solid-liquid interface.The structures of both Ca_(12)Al_(14)O_(33)(C12A7)and Y_(0.02)Ca_(11.98)Al_(14)O_(33)(Y-C12A7)were studied by using x-ray diffraction(XRD).Optical properties for C12A7 and Y-C12A7 single crystals have been studied in order to determine the optical parameters such as optical energy gap(Eg),refractive index n,oscillating energy(Eo),dispersion energy(Ed),volume energy loss function(VELF),and surface energy loss function(SELF).Finally,a new result for these samples is that the third-order nonlinear optical susceptibility(χ(3))was determined.The results have been discussed with effect of Y-doping on the C12A7 single crystals for optical and industrial applications.展开更多
Variation of nonlinear optical properties with surface roughness of ZnO thin films deposited on coming glass substrates at different annealing temperature (TA) was reported. The films were characterized by X-ray dif...Variation of nonlinear optical properties with surface roughness of ZnO thin films deposited on coming glass substrates at different annealing temperature (TA) was reported. The films were characterized by X-ray diffraction (XRD), UV-Vis-NIR transmission and single beam z-scan technique using second harmonics of Nd:YAG laser. Surface morphology of the samples was investigated by atomic force microscopy (AFM). Surface roughness was found minimum (8.4 nm) for ZnO sample annealed at 450℃. The nonlinear optical properties (NLO) were found to be dependent on surface roughness and the highest value of third order nonlinear susceptibility (X(3)=4.3x 10-7 esu) was obtained for ZnO at TA 450℃.展开更多
As a representative transition metal oxide,cupric oxide(CuO)has attracted a lot of interest in miscel-laneous fields.In the present work,the prominent third-order nonlinear optical(NLO)features of CuO nanosheets were ...As a representative transition metal oxide,cupric oxide(CuO)has attracted a lot of interest in miscel-laneous fields.In the present work,the prominent third-order nonlinear optical(NLO)features of CuO nanosheets were demonstrated via the typical Z-scan technique at 1 m m.The open-aperture(OA)Z-scan measurements at different intensities clearly showed that CuO nanosheets possessed the saturable ab-sorption(SA),reverse saturable absorption(RSA)and optical limiting behaviors.The closed-aperture(CA)Z-scan technology was implanted to investigate the nonlinear refractive index and the third-order nonlinear susceptibility.In virtue of the strong nonlinear optical absorption properties of CuO nano-sheets,a stable all-solid-state mode-locked laser with the as-prepared CuO nanosheets as saturable absorber at 1.06 m m was realized for the first time.Our work confirmed that CuO nanosheets exhibited outstanding NLO properties,which might stimulate the development in ultrafast photonics and nonlinear optics.展开更多
The determination of nonlinearities near the band edge of organic and polymeric electro-optic(EO)materials is important from the viewpoint of molecular nonlinear optics(NLO)and photonic device applications.Based on tr...The determination of nonlinearities near the band edge of organic and polymeric electro-optic(EO)materials is important from the viewpoint of molecular nonlinear optics(NLO)and photonic device applications.Based on transmission-mode Stark effect electromodulation(EM)spectroscopy,we study the electric-field-induced changes in optical absorption and refraction of newly developed EO polymers from the visible to near-infrared(NIR)wavelengths and report record-high near-band-edge complex EO effects from poled thin films.Values ofΔn andΔk up to 10^(-3) and 10^(-2) are found at an applied electric field of 2.0×10^(5)-3.0×10^(5)V/cm.The study of linear optical properties of poled films by spectroscopic ellipsometry shows large polinginduced birefringence and a nearly two-fold increase in the extinction coefficients at the extraordinary polarization.Through the Kramers-Kronig analysis,we obtained the real and imaginary second-order nonlinear coefficients up to~3,500 and~5,600 pm/V,respectively,which are believed to be the highest NLO coefficients of poled polymers through the resonance enhancement.Our approach goes beyond the previous works,applicable only to several discrete wavelengths,to a full-spectral analysis with independent verification of slab waveguide measurements.By considering both the electroabsorption and electrorefraction effects,our study overcomes the limitation of the classic qualitative two-level model and provides a quantitative understanding of near-resonance optical nonlinearities of organic EO materials.It can inspire the exploration of high-speed,absorptive,or phase-shifting light-modulators using EO polymers for on-chip applications.展开更多
40 Li_(2)O–5WO_(3)–(55-x)B_(2)O_(3):xV_(2)O_(5)(mol%)for 0.0≤x≤0.8 glasses were prepared by melt-quenching.Electric polarization was described in terms of the dielectric constant("0)and loss(tanδ).Mixed cond...40 Li_(2)O–5WO_(3)–(55-x)B_(2)O_(3):xV_(2)O_(5)(mol%)for 0.0≤x≤0.8 glasses were prepared by melt-quenching.Electric polarization was described in terms of the dielectric constant("0)and loss(tanδ).Mixed conduction phenomenon was explained by redox pairs V^(4+)↔V^(5+)and W^(5+)↔W^(6+) at high temperatures.Electronic polarizability(αe)was determined over a range of frequencies(100 Hz–100 kHz)and temperatures(30–280℃).The change of boron coordination in the glass network was explained with the aid of temperature coefficient of polarizability(φ).Nonlinear susceptibility(χ^((3)))and optical band gap(E°)were studied as a function of concentration of V_(2)O_(5).The highest values ofαe andχ^((3))were obtained at x=0.6 mol%.These glasses may find potential practical applications in the fields of solid-state ionics and nonlinear optics.展开更多
On the basis of ZINDO methods, according to the sum-overstates (SOS) expression, the program for the calculation of the second-order nonlinear optical susceptibilities βijk and βμ of molecules was devised, and the ...On the basis of ZINDO methods, according to the sum-overstates (SOS) expression, the program for the calculation of the second-order nonlinear optical susceptibilities βijk and βμ of molecules was devised, and the structures and nonlinear optical properties of unsymmetric bis(phenylethynyl) benzene series derivatives were studied. The influence of the molecular conjugated chain lengths, the donor and the acceptor on βμ was examined.展开更多
The second-order nonlinear optical susceptibilities β, βμ, and third-order non-linear optical susceptibilities γ, 〈γ〉 of a series of the novel push-pull multi-ring electro-photo polymer intermediates have been ...The second-order nonlinear optical susceptibilities β, βμ, and third-order non-linear optical susceptibilities γ, 〈γ〉 of a series of the novel push-pull multi-ring electro-photo polymer intermediates have been calculated. The influences of molecular structure, donor, acceptor and the frequency of external field on β and γ, and the relationship between γ and the number of thiophene rings (i. e. conjugated chain length) have been studied using INDO/SCI methods combined with sum-overstate (SOS) formula. The calculated results show that γ is proportional to 2.69 power of the chain length of the conjugated molecular bonds when the length is not quite long.展开更多
基金Supported by the Committee of Science and Tech nology of Wuhan(1320017010121)
文摘The density matrix approach has been employed to investigate the opticalnonlinear polarization in a single semiconductor quantum dot(QD). Electron states are considered tobe confined within a quantum dot with infinite potential barriers. It is shown, by numericalcalculation, that the third-order nonlinear optical susceptibilities for a typical Si quantum dot isdependent on the quantum size of the quantum dot and the frequency of incident light.
文摘By use of the Keldysh non-equilibrium Green’s-function methods, the third harmonic susceptibilities of two polyaniline families, PANI-HCl and PANI-H 3PO 4, are calculated [ x (3) ( ω )≈10 -12 esu]. It was found that the third harmonic susceptibility of polyaniline strongly depends on the delocalization of the electrons. The refractive indices n ( λ =589 nm) of PANI-HCl and PANI-H 3PO 4 are calculated by use of three common methods (the Lorentz-Lorentz theoretical model, the Gladstone-Dale group contribution and the Vogel group correlation) based on group contributions to molar refraction. The calculated n values are varied from 1.31 to 1.42 for PANI-HCl and 1.36 to 1.45 for PANI-H 3PO 4.
文摘A perturbative approach is used to study the AC response of nonlinear composite media, which obey a current-field relation of the form with components having nonlinear response at finite frequencies. For a sinusoidal applied field, we extend the local potential in terms of sinusoidal components at fundamental frequency and high-order harmonic frequencies to treat the nonlinear composites. For nonlinear composite media with a low concentrations of spherical inclusions, we give the formulae of the nonlinear effective AC susceptibility at the third harmonic frequency.
基金National Natural Science Foundation of China (60277002)
文摘Two novel poly[(3-alkylthiophene-2,5-diyl)-(benzylidenequinomethane-2,5-diyl)s] derivatives, poly[ (3-butylthiophene-2,5-diyl)-( p-N,N-dimethylamino) benzylidenequinomethane-2,5-diyl) ] ( PBTDMABQ) and poly [( 3-octylthiophene2,5-diyl) -(p-N, N-dimethylamino ) benzylidenequinomethane-2, 5-diyl)] (POTDMABQ), were synthesized.The band gaps of the two polymers are calculated as 1. 75 eV for PBTDMABQ and 1. 69 eV for POTDMABQ,respectively. The homogenous films of the two polymers were prepared and their third-ordernonlinear optical properties were studied by the backward degenerate four-wave mixing at 532 nm. Byusing the relative measurement technique, the third-order nonlinear optical susceptibilities ofPBTDMABQ and POTDMABQ are calculated as 5. 62 X 10^(-9) and 1. 22 X 10^(-8) ESU, respectively. It isfound that substituted alky groups have strong effects on the band gap and nonlinear opticalproperties of the two polymers. The relatively big third-order nonlinear optical susceptibilitiesand small band gap of POTDMABQ resulted mainly from the longer alkyl with strong electron-donatingability can enhance the delocation degree of conjugated π electronics.
文摘On the basis of ZINDO method and according to the sum over states(SOS) expression, the program is devised for the calculation of nonlinear second order optical susceptibilites β ijk and studying how different substituents on the phenyl ring attached to the atom silicon influence on the nonlinear second order optical properties of substituted silane series of molecules. The properties of (CH 3) 3Si? ?has been studied particularly. The effect of the length of silica chains on the calculated values has been studied too. The regularity summarized from the calculated results has been explained micromechanically.
文摘alculations of the nonlinear second-order optical susceptlbilities(β_(ijk))for sub- stituted tl1iophene derivative;with quinoidlike conformation are reported.These systetems possess small dipole moment;and large differences between dipole mo- ments of ground and first-excited states.Geometry optimizations of the molecules investigated were carried out using AM 1 method.The calculations were performed using INDO/CI method comboned with a sum-over-states expression for β_(jik). The calculated results sbw that the second-order susceptibility is a function of the na- ture and location of substituents and is larger for disubstituted molecules than monosubstituted molecules. Bipolymeric thiophenemetmne with NH_2/NO_2 groups was calctilated to have a β_μof 79. 920 × 10 ̄(-30) esu. It was found that the NH_2 and NO_2 groups in above disubstituted molecules are pull-pull groups in ground states,but are usual push-pull groups in the first excited states.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.61401395 and 61604128)the Scientific Research Fund of Zhejiang Provincial Education Department,China(Grant No.Y201533913)the Fundamental Research Funds for the Central Universities,China(Grant Nos.2016QNA4025 and 2016QN81002)
文摘Active metamaterials embedded with nonlinear elements are able to exhibit strong nonlinearity in microwave regime.However, existing S-parameter based parameter retrieval approaches developed for linear metamaterials do not apply in nonlinear cases. In this paper, a retrieval algorithm of high-order susceptibilities for nonlinear metamaterials is derived.Experimental demonstration shows that, by measuring the power level of each harmonic while sweeping the incident power,high-order susceptibilities of a thin-layer nonlinear metamaterial can be effectively retrieved. The proposed approach can be widely used in the research of active metamaterials.
文摘Considering two beams propagate in semiconductor crystal, this paper discusses the polarization dependence of pump beam-induced intensity attenuation of probe beam due to two-photon absorption (TPA). Numerical calculation and experimental measurement demonstrate that TPA coefficient is polarization dependent. For homogeneous materials, probe beam attenuation arises from the imaginary part of diagonal and off-diagonal components of third-order nonlinear susceptibilities.
基金Project supported by the National Natural Science Foundation of China(Grant Nos60308002and60678005)the Foundation for the Author of National Excellent Doctoral Dissertation of China(Grant No200339)+2 种基金the Foundation for Key Program of Ministry of Education,China(Grant No105156)the Fok Ying-Tong Education Foundation for Young Teachers in the Higher Education Institutions of China(Grant No101061)the Specialized Research Fund for the Doctoral Program of Higher Education of China(Grant No20050698017)
文摘We study the colour-locked twin-noisy-field correlation effects in the fifth-order nonlinear susceptibility of ultrafast polarization beats in a cascade four-level system. More importantly, the fifth-order phase-sensitive heterodyne detection of ultrafast polarization beats has been exploited. The fifth-order nonlinear optical response can be controlled and modified through the colour-locked correlation of twin noisy fields. Thus, this method with the phase dispersion information is a good way to measure the real and imaginary parts of the fifth-order nonlinear susceptibility.
文摘Ca_(12)Al_(14)O_(33)(C12A7)and Y_(0.02)Ca_(11.98)Al_(14)O_(33)(Y-C12A7)single crystals were grown by using the traveling-solvent floating zone(TSFZ)method.The temperature was increased to avoid the bubbles and cracks which may be formed during the preparation of the ingot material.We have started with the flux higher than the normal to avoid the bubbles and make good treatment for the solid-liquid interface.The structures of both Ca_(12)Al_(14)O_(33)(C12A7)and Y_(0.02)Ca_(11.98)Al_(14)O_(33)(Y-C12A7)were studied by using x-ray diffraction(XRD).Optical properties for C12A7 and Y-C12A7 single crystals have been studied in order to determine the optical parameters such as optical energy gap(Eg),refractive index n,oscillating energy(Eo),dispersion energy(Ed),volume energy loss function(VELF),and surface energy loss function(SELF).Finally,a new result for these samples is that the third-order nonlinear optical susceptibility(χ(3))was determined.The results have been discussed with effect of Y-doping on the C12A7 single crystals for optical and industrial applications.
基金DRDO,UGC and DST for financial support under SAP and FIST program,respectively
文摘Variation of nonlinear optical properties with surface roughness of ZnO thin films deposited on coming glass substrates at different annealing temperature (TA) was reported. The films were characterized by X-ray diffraction (XRD), UV-Vis-NIR transmission and single beam z-scan technique using second harmonics of Nd:YAG laser. Surface morphology of the samples was investigated by atomic force microscopy (AFM). Surface roughness was found minimum (8.4 nm) for ZnO sample annealed at 450℃. The nonlinear optical properties (NLO) were found to be dependent on surface roughness and the highest value of third order nonlinear susceptibility (X(3)=4.3x 10-7 esu) was obtained for ZnO at TA 450℃.
基金The National Natural Science Foundation of China(12004213,21872084).
文摘As a representative transition metal oxide,cupric oxide(CuO)has attracted a lot of interest in miscel-laneous fields.In the present work,the prominent third-order nonlinear optical(NLO)features of CuO nanosheets were demonstrated via the typical Z-scan technique at 1 m m.The open-aperture(OA)Z-scan measurements at different intensities clearly showed that CuO nanosheets possessed the saturable ab-sorption(SA),reverse saturable absorption(RSA)and optical limiting behaviors.The closed-aperture(CA)Z-scan technology was implanted to investigate the nonlinear refractive index and the third-order nonlinear susceptibility.In virtue of the strong nonlinear optical absorption properties of CuO nano-sheets,a stable all-solid-state mode-locked laser with the as-prepared CuO nanosheets as saturable absorber at 1.06 m m was realized for the first time.Our work confirmed that CuO nanosheets exhibited outstanding NLO properties,which might stimulate the development in ultrafast photonics and nonlinear optics.
基金supported by the Fundamental Research Project Funding from Shenzhen Science & Technology Innovation Committee (JCYJ20180507181718203)the National Natural Science Foundation of China (21975213)+2 种基金the Research Grants Council (RGC) of Hong Kong (11306320, 11303618, 11210218)the City University of Hong Kong (9610389, 9680263, 9610454)the Innovation and Technology Commission of Hong Kong (ITS/461/18)。
文摘The determination of nonlinearities near the band edge of organic and polymeric electro-optic(EO)materials is important from the viewpoint of molecular nonlinear optics(NLO)and photonic device applications.Based on transmission-mode Stark effect electromodulation(EM)spectroscopy,we study the electric-field-induced changes in optical absorption and refraction of newly developed EO polymers from the visible to near-infrared(NIR)wavelengths and report record-high near-band-edge complex EO effects from poled thin films.Values ofΔn andΔk up to 10^(-3) and 10^(-2) are found at an applied electric field of 2.0×10^(5)-3.0×10^(5)V/cm.The study of linear optical properties of poled films by spectroscopic ellipsometry shows large polinginduced birefringence and a nearly two-fold increase in the extinction coefficients at the extraordinary polarization.Through the Kramers-Kronig analysis,we obtained the real and imaginary second-order nonlinear coefficients up to~3,500 and~5,600 pm/V,respectively,which are believed to be the highest NLO coefficients of poled polymers through the resonance enhancement.Our approach goes beyond the previous works,applicable only to several discrete wavelengths,to a full-spectral analysis with independent verification of slab waveguide measurements.By considering both the electroabsorption and electrorefraction effects,our study overcomes the limitation of the classic qualitative two-level model and provides a quantitative understanding of near-resonance optical nonlinearities of organic EO materials.It can inspire the exploration of high-speed,absorptive,or phase-shifting light-modulators using EO polymers for on-chip applications.
基金The authors wish to thank management of VNRVJIET for their support to accomplish this research work.And,the authors(Dr.L.Srinivasa Rao and Dr.P.Raghavendra Rao)would like to thank Jawaharlal Nehru Technological Uni-versity Hyderabad for awarding a research project(Proc.No.JNTUH/TEQIP-III/CRS/2019/Physics/06).
文摘40 Li_(2)O–5WO_(3)–(55-x)B_(2)O_(3):xV_(2)O_(5)(mol%)for 0.0≤x≤0.8 glasses were prepared by melt-quenching.Electric polarization was described in terms of the dielectric constant("0)and loss(tanδ).Mixed conduction phenomenon was explained by redox pairs V^(4+)↔V^(5+)and W^(5+)↔W^(6+) at high temperatures.Electronic polarizability(αe)was determined over a range of frequencies(100 Hz–100 kHz)and temperatures(30–280℃).The change of boron coordination in the glass network was explained with the aid of temperature coefficient of polarizability(φ).Nonlinear susceptibility(χ^((3)))and optical band gap(E°)were studied as a function of concentration of V_(2)O_(5).The highest values ofαe andχ^((3))were obtained at x=0.6 mol%.These glasses may find potential practical applications in the fields of solid-state ionics and nonlinear optics.
基金Project supported by the National Natural Science Foundation of China (Nos. 29890210, 29573104) and the Key Laboratory for Supramolecular Structure and Spectroscopy of Jilin Universtiy.
文摘On the basis of ZINDO methods, according to the sum-overstates (SOS) expression, the program for the calculation of the second-order nonlinear optical susceptibilities βijk and βμ of molecules was devised, and the structures and nonlinear optical properties of unsymmetric bis(phenylethynyl) benzene series derivatives were studied. The influence of the molecular conjugated chain lengths, the donor and the acceptor on βμ was examined.
基金Project supported by the National Natural Science Foundation of China (No. 29890210)
文摘The second-order nonlinear optical susceptibilities β, βμ, and third-order non-linear optical susceptibilities γ, 〈γ〉 of a series of the novel push-pull multi-ring electro-photo polymer intermediates have been calculated. The influences of molecular structure, donor, acceptor and the frequency of external field on β and γ, and the relationship between γ and the number of thiophene rings (i. e. conjugated chain length) have been studied using INDO/SCI methods combined with sum-overstate (SOS) formula. The calculated results show that γ is proportional to 2.69 power of the chain length of the conjugated molecular bonds when the length is not quite long.