Based on the Schr ¨odinger equation for envelope function in the effective mass approximation, linear and nonlinear optical absorption coefficients in a multi-subband lens quantum dot are investigated. The effect...Based on the Schr ¨odinger equation for envelope function in the effective mass approximation, linear and nonlinear optical absorption coefficients in a multi-subband lens quantum dot are investigated. The effects of quantum dot size on the interband and intraband transitions energy are also analyzed. The finite element method is used to calculate the eigenvalues and eigenfunctions. Strain and In-mole-fraction effects are also studied, and the results reveal that with the decrease of the In-mole fraction, the amplitudes of linear and nonlinear absorption coefficients increase. The present computed results show that the absorption coefficients of transitions between the first excited states are stronger than those of the ground states. In addition, it has been found that the quantum dot size affects the amplitudes and peak positions of linear and nonlinear absorption coefficients while the incident optical intensity strongly affects the nonlinear absorption coefficients.展开更多
The nonlinear optical properties of an azobenzene polymer azo12–MO were investigated by a Z-scan technique.The polymer was synthesized by assembling the liquid-crystalline polymer azo12 with methyl orange.The nonline...The nonlinear optical properties of an azobenzene polymer azo12–MO were investigated by a Z-scan technique.The polymer was synthesized by assembling the liquid-crystalline polymer azo12 with methyl orange.The nonlinear refractive index(1.39×10 15cm2/W)and the nonlinear absorption coefficient(0.11 cm/GW)of azo12–MO were determined with 532-nm picosecond laser pulses at the irradiance of 92.40 GW/cm2.When compared to the nonlinear properties of azo12 and methyl orange,azo12–MO possesses the advantages of its two constituents and shows larger nonlinear optical properties.展开更多
The nonlinear refractive index and absorption coefficient of single\|shell semiconductor carbon nanotubes(CN s ) are calculated based on the two\|band approximation and Genkin\|Mednis approach. The results of nonlinea...The nonlinear refractive index and absorption coefficient of single\|shell semiconductor carbon nanotubes(CN s ) are calculated based on the two\|band approximation and Genkin\|Mednis approach. The results of nonlinear refractive index and absorption coefficient reach the order of 10 -8 and 10 -4 cm 2\5W -1 separately, which indicates that CN s have wonderful nonlinear optical properties. Taking into account the temperature effect and overlapping of σ and π orbits, the effect of relaxation term and chiral angle is discussed. The results show that the smaller the relaxation term, the larger the nonlinear absorption coefficient and refractive index. At the same time, CN s with different chiral angles have different results due to their different energy gap.展开更多
We investigate the diffusion interaction and quantitative analysis of zinc dialkyldithiophosphate (ZDDP) mixed with lube base oil (LBO) at different concentrations using terahertz time-domain spectroscopy (THzTDS).Whe...We investigate the diffusion interaction and quantitative analysis of zinc dialkyldithiophosphate (ZDDP) mixed with lube base oil (LBO) at different concentrations using terahertz time-domain spectroscopy (THzTDS).When the concentration exceeds 6.78%,the characteristic absorption peaks exhibit significantly shift,and the absorption coefficient peak value is nonlinear against concentration.Moreover,the absorption coefficients of mixed samples follow the Beer's law at a concentration below 6.78%.The quantitative analysis enables a strategy for monitoring the formulation of lubricating oil in real time.展开更多
Niobic tellurite glass doped by silver chloride nanocrystal was prepared with the melting-quenching and heat treatment method, and the self-trapped exciton absorption band of the silver chloride nanocrystal was observ...Niobic tellurite glass doped by silver chloride nanocrystal was prepared with the melting-quenching and heat treatment method, and the self-trapped exciton absorption band of the silver chloride nanocrystal was observed at 532 nm in the UV-visible absorption spectrum. The glass structure characteristics were investigated by Raman spectroscopy, and the mechanism of self-trapped exciton was analyzed by Jahn-Teller model. Its optical limiting was measured with 532 nm picosecond laser pulses, and the corresponding nonlinear absorption coefficient was measured with open-aperture Z-scan. The experimental results showed that optical limiting at 532 nm was attributed to free carrier absorption between the self-trapped state and the continuum band.展开更多
In this Letter, the effects of the iron(Fe) dopant concentration on the nonlinear optical properties of iron-doped ferroelectric X-cut Li Nb O3 crystals plates are studied by using the Z-scan technique with a cw laser...In this Letter, the effects of the iron(Fe) dopant concentration on the nonlinear optical properties of iron-doped ferroelectric X-cut Li Nb O3 crystals plates are studied by using the Z-scan technique with a cw laser at the wavelength of 532 nm. The amount of iron in the compound is varied from 0 to 0.15 mol%. Measurements of nonlinear refractive index n2 and the nonlinear absorption coefficient β are determined. The sign of the nonlinear refractive index is found to be negative and the magnitude is on the order of 10-8cm2∕W. This nonlinear effect increases as the concentration increases from 0 to 0.15 mol%. A good linear relationship is obtained between nonlinear refractive index, nonlinear absorption coefficient, and concentration.展开更多
基金Project supported by the Ministry of Higher Education and Scientific Research in Iraq,Ibnu Sina Institute and Physics Department of Universiti Teknologi Malaysia(UTM RUG Vote No.06-H14)
文摘Based on the Schr ¨odinger equation for envelope function in the effective mass approximation, linear and nonlinear optical absorption coefficients in a multi-subband lens quantum dot are investigated. The effects of quantum dot size on the interband and intraband transitions energy are also analyzed. The finite element method is used to calculate the eigenvalues and eigenfunctions. Strain and In-mole-fraction effects are also studied, and the results reveal that with the decrease of the In-mole fraction, the amplitudes of linear and nonlinear absorption coefficients increase. The present computed results show that the absorption coefficients of transitions between the first excited states are stronger than those of the ground states. In addition, it has been found that the quantum dot size affects the amplitudes and peak positions of linear and nonlinear absorption coefficients while the incident optical intensity strongly affects the nonlinear absorption coefficients.
基金Project supported by the National Natural Science Foundation of China (Grant No.11174203)
文摘The nonlinear optical properties of an azobenzene polymer azo12–MO were investigated by a Z-scan technique.The polymer was synthesized by assembling the liquid-crystalline polymer azo12 with methyl orange.The nonlinear refractive index(1.39×10 15cm2/W)and the nonlinear absorption coefficient(0.11 cm/GW)of azo12–MO were determined with 532-nm picosecond laser pulses at the irradiance of 92.40 GW/cm2.When compared to the nonlinear properties of azo12 and methyl orange,azo12–MO possesses the advantages of its two constituents and shows larger nonlinear optical properties.
文摘The nonlinear refractive index and absorption coefficient of single\|shell semiconductor carbon nanotubes(CN s ) are calculated based on the two\|band approximation and Genkin\|Mednis approach. The results of nonlinear refractive index and absorption coefficient reach the order of 10 -8 and 10 -4 cm 2\5W -1 separately, which indicates that CN s have wonderful nonlinear optical properties. Taking into account the temperature effect and overlapping of σ and π orbits, the effect of relaxation term and chiral angle is discussed. The results show that the smaller the relaxation term, the larger the nonlinear absorption coefficient and refractive index. At the same time, CN s with different chiral angles have different results due to their different energy gap.
基金supported by the Program for New Century Excellent Talents in University (No. NCET-08-0841)the National Natural Science Foundation of China (Nos. 50672132,60778034,and 60877038)+1 种基金the Research Fund for the Doctoral Program of Higher Education (No. 200804250006)the State Key Laboratory of Heavy Oil Processing,China University of Petroleum (No. 2008-14)
文摘We investigate the diffusion interaction and quantitative analysis of zinc dialkyldithiophosphate (ZDDP) mixed with lube base oil (LBO) at different concentrations using terahertz time-domain spectroscopy (THzTDS).When the concentration exceeds 6.78%,the characteristic absorption peaks exhibit significantly shift,and the absorption coefficient peak value is nonlinear against concentration.Moreover,the absorption coefficients of mixed samples follow the Beer's law at a concentration below 6.78%.The quantitative analysis enables a strategy for monitoring the formulation of lubricating oil in real time.
基金Supported by Shanghai Leading Academic Discipline Project (Grant No. B408)National Basic Research Program of China (Grant Nos. 2006CB806006, 2006CB921105)+1 种基金Program for Changjiang Scholars and Innovative Research Team in University, Doctoral Program of High Education (Grant No. 20050269011)Project sponsored by Shanghai Science and Technology Committee (Grant Nos. 06DJ14008, 07dz22025, 06QH14003)
文摘Niobic tellurite glass doped by silver chloride nanocrystal was prepared with the melting-quenching and heat treatment method, and the self-trapped exciton absorption band of the silver chloride nanocrystal was observed at 532 nm in the UV-visible absorption spectrum. The glass structure characteristics were investigated by Raman spectroscopy, and the mechanism of self-trapped exciton was analyzed by Jahn-Teller model. Its optical limiting was measured with 532 nm picosecond laser pulses, and the corresponding nonlinear absorption coefficient was measured with open-aperture Z-scan. The experimental results showed that optical limiting at 532 nm was attributed to free carrier absorption between the self-trapped state and the continuum band.
文摘In this Letter, the effects of the iron(Fe) dopant concentration on the nonlinear optical properties of iron-doped ferroelectric X-cut Li Nb O3 crystals plates are studied by using the Z-scan technique with a cw laser at the wavelength of 532 nm. The amount of iron in the compound is varied from 0 to 0.15 mol%. Measurements of nonlinear refractive index n2 and the nonlinear absorption coefficient β are determined. The sign of the nonlinear refractive index is found to be negative and the magnitude is on the order of 10-8cm2∕W. This nonlinear effect increases as the concentration increases from 0 to 0.15 mol%. A good linear relationship is obtained between nonlinear refractive index, nonlinear absorption coefficient, and concentration.
