Particle swarm optimization(PSO) and invasive weed optimization(IWO) algorithms are used for extracting the modeling parameters of materials useful for optics and photonics research community. These two bio-inspired a...Particle swarm optimization(PSO) and invasive weed optimization(IWO) algorithms are used for extracting the modeling parameters of materials useful for optics and photonics research community. These two bio-inspired algorithms are used here for the first time in this particular field to the best of our knowledge. The algorithms are used for modeling graphene oxide and the performances of the two are compared. Two objective functions are used for different boundary values. Root mean square(RMS) deviation is determined and compared.展开更多
The profile method is the principal method first to be chosen to measure the apparent optical parameters of waters. This paper first introduces the profile method briefly, then modifies Ⅱthe applied algorithm in the ...The profile method is the principal method first to be chosen to measure the apparent optical parameters of waters. This paper first introduces the profile method briefly, then modifies Ⅱthe applied algorithm in the light of the properties of the class- waters and lastly, analyses the effect of application.展开更多
The different optical dispersion parameters of SrLaAIO4 single crystals have been studied by the transmission andreflection measurements at normal incidence for the three orientations 001, 100 and 101 in the spectral ...The different optical dispersion parameters of SrLaAIO4 single crystals have been studied by the transmission andreflection measurements at normal incidence for the three orientations 001, 100 and 101 in the spectral range400 nm^2500 nm.The optical absorption data revealed the existance of allowed indirect and direct transition. Therefractive index has abnormal behaviour in the spectral region 400~900 nm, but has a normal one in the higherwavelength region. The optical dispersion parameters, the single oscillator energy Eo and the dispersion energy Edwere determined and indicated the ionic structure of the material. The high-frequency dielectric constant, the latticedielectric constant and the electronic polarizability were determined by the free carriers and the lattice vibrationmodes. The real dielectric constant (?)1, the dielectric loss tangent (tanδ), the volume (VELF) and the surface energyloss function (SELF) have also been discussed.展开更多
Geometry parameters of optical fiber are crucial in evaluating the quality of the optical fiber.Near⁃field light distribution method is recommended in GB15972.20-2008 for the measurement of geometry parameters.To dist...Geometry parameters of optical fiber are crucial in evaluating the quality of the optical fiber.Near⁃field light distribution method is recommended in GB15972.20-2008 for the measurement of geometry parameters.To distinguish the boundary between fiber core and cladding,it is necessary to illuminate the fiber.The end face of the core is a bright spot with unclear edge,so the true edge of the core and the cladding cannot be accurately judged.A method is proposed in this paper to measure the geometry parameters of optical fiber by Bessel function fitting.Theoretically,the solution to the electromagnetic vector of mode field satisfies Bessel function,and the boundary between the core and the cladding can be precisely extracted by Bessel function fitting.Edges of the fiber were fitted by elliptical curves,and the geometry parameters of the fibers could be calculated.Results show that the maximum deviations of the diameters and the average differences of the fibers were decreased under normal and abnormal conditions respectively.The proposed method is an efficient way to obtain edge data and can improve the accuracy and stability of geometry parameters of optical fibers.展开更多
This study underscores the significance of online monitoring of standard substances for bituminous coal and anthracite,two commonly used fossil fuels.Terahertz technology emerges as a powerful non-destructive detectio...This study underscores the significance of online monitoring of standard substances for bituminous coal and anthracite,two commonly used fossil fuels.Terahertz technology emerges as a powerful non-destructive detection method capable of revealing the physical and chemical properties of measured objects.In this research,terahertz time-domain spectroscopy technology was employed to investigate the spectral characteristics of four distinct types of bituminous coal and anthracite samples.The refractive index and absorption coefficient spectra of these samples were calculated across a frequency range of 0.5 THz to 2.5 THz.Furthermore,principal component analysis was conducted using all refractive index and absorption coefficient data within this frequency band.Through the analysis and comparison with known parameters of coal standard materials,it was established that carbon content primarily influences the refractive index of bituminous coal and anthracite,while ash content predominantly affects the absorption effect.These findings underscore the potential of terahertz spectroscopy in conjunction with principal component analysis to qualitatively assess the similarities and differences between coal samples,thus offering novel insights for the online monitoring of diverse coal types and qualities.展开更多
Parametric down-conversion is a useful method to obtain non-classical state in quantum optics. （1） An analytical solution to the Fokker-Planck equation of non-degenerate optical parametric amplification （NOPA） fo...Parametric down-conversion is a useful method to obtain non-classical state in quantum optics. （1） An analytical solution to the Fokker-Planck equation of non-degenerate optical parametric amplification （NOPA） for generation of squeezed light is presented. The maximum intra-cavity compression of squeezed light derived from the analytical solution is 1/16 （vacuum fluctuations 1/4）. To compare it with the previous 1/8 of degenerate optical parametric amplification （DOPA）, it seems that squeezing for NOPA is superior to DOPA.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
The perfect photon absorption is studied in a cavity quantum electrodynamics(CQED) system, in which an optical parameter amplifier(OPA) is coupled to the cavity mode. This makes it possible to control the optical phas...The perfect photon absorption is studied in a cavity quantum electrodynamics(CQED) system, in which an optical parameter amplifier(OPA) is coupled to the cavity mode. This makes it possible to control the optical phase to realize the perfect photon absorption. It is found that in the presence of one and two injected fields, the perfect photon absorption is present in these two cases and can be controlled by adjusting the parametric phase. Moreover, different from the previous predictions of perfect photon absorption in atomic CQED systems, the perfect photon absorption can be changed significantly by the relative phase. Our work provides a new platform to use the parametric processes to make an available way to control the behaviors of photons and to take advantage of the optical phase to achieve the perfect photon absorption.展开更多
The optical parameters for three samples of intrinsic, doped Si and doped Mg (Al x Ga 1- x ) y In 1- y P prepared by the MOCVD on GaAs substrate were measured by using ellipsometry and were calc...The optical parameters for three samples of intrinsic, doped Si and doped Mg (Al x Ga 1- x ) y In 1- y P prepared by the MOCVD on GaAs substrate were measured by using ellipsometry and were calculated by the two-layer absorption film model. The results obtained were discussed. The grown rates and thickness of oxidic layer on the intrinsic (Al x Ga 1- x ) y In 1- y P surface exposed in the atmosphere were studied. A linear dependence of oxidic layer thickness on the time was obtained.展开更多
Dy^3＋-doped borate glasses （LBLB） with high effective visible fluorescence emission were synthesized. The absorption spectrum and fluorescence spectrum of this glass were measured and analyzed. By using J-O theory,...Dy^3＋-doped borate glasses （LBLB） with high effective visible fluorescence emission were synthesized. The absorption spectrum and fluorescence spectrum of this glass were measured and analyzed. By using J-O theory, the oscillator strengths for some absorption transitions were calculated according to the absorption spectra. The intensity parameters Ω1 （t = 2, 4, 6） of Dy^3＋ were determined by using a least-squares fitting approach, and the values are 4.04 × 10^-20, 1.30 × 10^-20 and 1.82 × 10^-20 cm, respectively. The root-mean-square deviation δrma was calculated. Under UV light excitation, Dy^3＋-doped borate glasses （LBLB） emit intense yellowish white lights. The excitation spectrum indicates that argon laser is the effective excitation source in Dy^3＋-doped LBLB glasses展开更多
Optical parametric lasers widely using in many science and technology field owin g to its merit of wide tunable spectrum range.But common optical parametric lase rs achieve tune by change of angel or temperature.The t...Optical parametric lasers widely using in many science and technology field owin g to its merit of wide tunable spectrum range.But common optical parametric lase rs achieve tune by change of angel or temperature.The tune velocity and tune pre cision of these tune modes does not satisfy in many applications.The reporting i nto an optical parametric laser which achieve tune by electooptic effect,that have got speediness tune velocity and relatively quite tune precision. The optical parametric device design based on parametric fluorescent produce thr ough sum frequency phase matching in nonlinear optical crystals.It is a tune pr o cess of refractive index about parametric and pump light in nonlinear optical cr ystals namely.But refractive index of nonlinear optical crystals possess electro o ptic effect can change via apply transformable electro field.This change only w a nts a time of ns grade.So optical parametric device with nonlinear optical cryst als possess suitability electrooptic effect can realize speediness tune in princ iple.The idea about design on the recommended device here is somewhat as follows .The tune model is phase tuning.To strive increase the effect of electro optic f unction under keep immovable polarization directions of 3 wavelength in the opti cal parametric process,to strive convenient for apply electro field,the electro field is only sensitive for a refractive index of some wavelength in specificall y spectrum region.The principium examination has showed that the idea is reasona ble.Our count have show also that its tune precision same as expectance.展开更多
This paper reports that a series of Nd3＋：Er3＋：yb3＋ co-doped borosilicate glasses have been prepared and their absorption spectra measured. The J-O intensity parameters Ωk （k = 2, 4, 6）, spontaneous radiative l...This paper reports that a series of Nd3＋：Er3＋：yb3＋ co-doped borosilicate glasses have been prepared and their absorption spectra measured. The J-O intensity parameters Ωk （k = 2, 4, 6）, spontaneous radiative lifetime Trad, spontaneous transition probability A, fluorescence branching ratio β and oscillator strength fed of the Nd3＋ ions at room temperature are calculated based on Judd-Ofelt （J-O） theory. The temperature dependence of the up-conversion photoluminescence characteristics in a Nd3＋：Er3＋：Yb3＋ co-doped sample is studied under a 978 nm semiconductor laser excitation, and the energy transfer mechanisms among Yb3＋, Er3＋ and Nd3＋ ions are analysed. The results show that the J-O intensity parameters Ω2 increase when the Nd3＋ concentration of the Nd3＋：Er3＋：yb3＋ co-doped borosilicate glasses increases. The possibility of spontaneous transition is small and lifetimes are long at levels of 4F5/2 and 4F3/2. The intensity of Nd3＋ emissions at 595, 691, 753, 813 and 887 nm axe markedly enhanced when the sample temperature exceeds 400 K. The reasons being the cooperation of the secondary sensitization from Era＋ to Nd3＋ and the contribution of a multi-phonon.展开更多
Single crystal Ga X In 1-X As films have grown up on GaAs(100) substrate at 375℃ and on InP(100) substrate at 390℃, respectively, by the method of rf sputtering with using undoped GaInAs polycrystal as ...Single crystal Ga X In 1-X As films have grown up on GaAs(100) substrate at 375℃ and on InP(100) substrate at 390℃, respectively, by the method of rf sputtering with using undoped GaInAs polycrystal as target. However, on Si(100) or Si(111) substrates at 260～390℃, even at 465℃, only polycrystalline films were obtained. In addition, the structure, composition, electrical characteristic and optical properties of the Ga X In 1-X As films were investigated using X ray diffraction (XRD), reflection of high energy electron diffraction (RHEED), energy dispersion analyzer of X ray (EDAX), Hall measurements and spectroscopic ellipsometry.展开更多
A vectorial optical field generator(VOF-Gen) based on two reflective phase-only liquid crystal spatial light modulators enables the creation of an arbitrary optical complex field. In this work, the capabilities of the...A vectorial optical field generator(VOF-Gen) based on two reflective phase-only liquid crystal spatial light modulators enables the creation of an arbitrary optical complex field. In this work, the capabilities of the VOF-Gen in terms of manipulating the spatial distributions of phase, amplitude, and polarization are experimentally demonstrated by generating a radially polarized optical field consisted of five annular rings, the focusing properties of which are also numerically studied with vectorial diffraction theory. By carefully adjusting the relative amplitude and phase between the adjacent rings, an optical needle field with purely longitudinal polarization can be produced in the focal region of a high numerical aperture lens. The versatile method presented in this work can be easily extended to the generation of a vectorial optical field with any desired complex distributions.展开更多
The research findings of the phase composition,nanostructure and optical properties of strontium-barium niobate thin films are discussed.Sr_(x)Ba_(1−x)Nb_(2)O_(6)nanosized films(x=0.5 and 0.61)were characterized by XR...The research findings of the phase composition,nanostructure and optical properties of strontium-barium niobate thin films are discussed.Sr_(x)Ba_(1−x)Nb_(2)O_(6)nanosized films(x=0.5 and 0.61)were characterized by XRD,SEM and AFM studies.Reflective multi-angle ellipsometry and spectrophotometry were used to determine the optical parameters(refractive index,its dispersion,and thickness of the damaged surface layer)of thin films.It was shown that SBN-50 and SBN-61 thin films were grown c-oriented on Al_(2)O_(3)(0001)and heteroepitaxial on MgO(001)substrates.The increase of refractive index,approaching its maximum value in the bulk material for a given composition as the film thickness increases,is observed.展开更多
Background Optical coherence tomography （OCT） is a high resolution noncontact imaging modality which can quantitatively detect the optic disc and retinal structure.This study was designed to evaluate the diagnostic ...Background Optical coherence tomography （OCT） is a high resolution noncontact imaging modality which can quantitatively detect the optic disc and retinal structure.This study was designed to evaluate the diagnostic capability of parameters of the optic disc, retinal nerve fiber layer thickness, and ganglion cell complex （GCC） using a new technology called Fourier-domain OCT （FD-OCT） for early primary open angle glaucoma （POAG） patients.Methods Two groups of patients, early perimetric damage POAG and normal subjects were included in this observational cross-sectional study.All patients underwent FD-OCT and visual field examination in addition to full ophthalmic examinations.Receiver operating characteristic curves （ROC） were studied for all parameters.The sensitivity and specificity for distinguishing between normal and early glaucomatous eyes, the areas under the receiver operating characteristic curves （AROC） and positive, negative likelihood ratios were evaluated for all the single parameters and selected combined parameters using arbitrary cutoffs.Results Thirty-four eyes of 34 early POAG patients and 42 eyes of 42 normal subjects were analyzed.Cup/disc （C/D）vertical ratio presented the best sensitivity and positive likelihood ratio for selected specificities （95% and 85%） which were 79.4% and 88.2%, 33.4 and 7.4, respectively.Among all single parameters, the C/D vertical ratio demonstrated the highest AROC which was at 0.930.The average thickness of circumpapillary RNFL on 3.45 mm showed the highest AROC among all of the peripapillary RNFL parameters.The sensitivity at selected specificity and AROC of GCC were not as high as C/D vertical ratio and RNFL AT on 3.45 mm.When the C/D vertical ratio, RNFL AT on 3.45 mm, and rim area were combined using a logistical diagnostic model, the AROC was raised to 0.949 but not significantly different from the top single parameter, C/D vertical ratio.Conclusions The key parameters obtained by FD-OCT were able to show the significant differences of optic discs,thickness of RNFL and GCC between POAG patients and normal subjects.According to sensitivity, specificity, likelihood ratio and AROC, the top three parameters from FD-OCT for early diagnosis of POAG were C/D vertical ratio, RNFL AT on 3.45 mm, and the rim area.展开更多
A real-time method for measuring atmospheric parameters based on co-processor field-programmable gate array （FPGA） and main processor digital signal processing （DSP） is proposed for ground-based telescopes with ad...A real-time method for measuring atmospheric parameters based on co-processor field-programmable gate array （FPGA） and main processor digital signal processing （DSP） is proposed for ground-based telescopes with adaptive optics （AO） systems. Coherence length, outer scale, average wind speed, and coherence time are estimated according to closed-loop data on the residual slopes and the corrected voltages of AO systems. This letter introduces the principle and architecture design of the proposed method, which is successfully applied in the 127-element AO system of the 1.8-m telescope of Yunnan Astronomical Observatory. The method enables real-time atmospheric observations with the same object and path of the AO system. This method is also applicable to extended objects.展开更多
The new organic-inorganic compound, [C_6H_7N_2O_2]_3TeCl_5·2Cl was synthesized and its structure was determined at room temperature in the triclinic system （P^-1） with the following parameters： a = 10.5330（11...The new organic-inorganic compound, [C_6H_7N_2O_2]_3TeCl_5·2Cl was synthesized and its structure was determined at room temperature in the triclinic system （P^-1） with the following parameters： a = 10.5330（11） ？, b = 10.6663（11） ？, c = 15.9751（16）？, α = 82.090（2）°, β = 71.193（2）°, γ = 68.284（2）°and Z = 2. The final cycle of refinement led to R = 0.057 and Rw = 0.149. The crystal structure was stabilized by an extensive network of N--H···Cl and non-classical C--H···Cl hydrogen bonds between the cation and the anionic group. Several thermal analysis techniques such as thermogravimetric analysis, differential scanning calorimetric analysis and evolved gas analysis were used. We used isoconversional kinetics methods to determine the kinetics parameters. We observe that the decomposition of [C_6H_7N_2O_2]_3TeCl_5·2Cl entails the formation hydrochloric acid of nitroaniline as volatiles. The infrared spectra were recorded in the4000–400 cm^（-1）frequency region. The Raman spectra were recorded in the external region of the anionic sublattice vibration 50–1500 cm^（-1）. The optical band gap was calculated from the UV-Vis absorbance spectra using classical Tauc relation which was found to be 3.12 and 3.67 eV.展开更多
文摘Particle swarm optimization(PSO) and invasive weed optimization(IWO) algorithms are used for extracting the modeling parameters of materials useful for optics and photonics research community. These two bio-inspired algorithms are used here for the first time in this particular field to the best of our knowledge. The algorithms are used for modeling graphene oxide and the performances of the two are compared. Two objective functions are used for different boundary values. Root mean square(RMS) deviation is determined and compared.
文摘The profile method is the principal method first to be chosen to measure the apparent optical parameters of waters. This paper first introduces the profile method briefly, then modifies Ⅱthe applied algorithm in the light of the properties of the class- waters and lastly, analyses the effect of application.
文摘The different optical dispersion parameters of SrLaAIO4 single crystals have been studied by the transmission andreflection measurements at normal incidence for the three orientations 001, 100 and 101 in the spectral range400 nm^2500 nm.The optical absorption data revealed the existance of allowed indirect and direct transition. Therefractive index has abnormal behaviour in the spectral region 400~900 nm, but has a normal one in the higherwavelength region. The optical dispersion parameters, the single oscillator energy Eo and the dispersion energy Edwere determined and indicated the ionic structure of the material. The high-frequency dielectric constant, the latticedielectric constant and the electronic polarizability were determined by the free carriers and the lattice vibrationmodes. The real dielectric constant (?)1, the dielectric loss tangent (tanδ), the volume (VELF) and the surface energyloss function (SELF) have also been discussed.
基金Sponsored by the National Science Foundation for Young Scholars of China(Grant No.61605114).
文摘Geometry parameters of optical fiber are crucial in evaluating the quality of the optical fiber.Near⁃field light distribution method is recommended in GB15972.20-2008 for the measurement of geometry parameters.To distinguish the boundary between fiber core and cladding,it is necessary to illuminate the fiber.The end face of the core is a bright spot with unclear edge,so the true edge of the core and the cladding cannot be accurately judged.A method is proposed in this paper to measure the geometry parameters of optical fiber by Bessel function fitting.Theoretically,the solution to the electromagnetic vector of mode field satisfies Bessel function,and the boundary between the core and the cladding can be precisely extracted by Bessel function fitting.Edges of the fiber were fitted by elliptical curves,and the geometry parameters of the fibers could be calculated.Results show that the maximum deviations of the diameters and the average differences of the fibers were decreased under normal and abnormal conditions respectively.The proposed method is an efficient way to obtain edge data and can improve the accuracy and stability of geometry parameters of optical fibers.
基金Anhui Province Natural Science Research Project for Universities(2022AH052272)。
文摘This study underscores the significance of online monitoring of standard substances for bituminous coal and anthracite,two commonly used fossil fuels.Terahertz technology emerges as a powerful non-destructive detection method capable of revealing the physical and chemical properties of measured objects.In this research,terahertz time-domain spectroscopy technology was employed to investigate the spectral characteristics of four distinct types of bituminous coal and anthracite samples.The refractive index and absorption coefficient spectra of these samples were calculated across a frequency range of 0.5 THz to 2.5 THz.Furthermore,principal component analysis was conducted using all refractive index and absorption coefficient data within this frequency band.Through the analysis and comparison with known parameters of coal standard materials,it was established that carbon content primarily influences the refractive index of bituminous coal and anthracite,while ash content predominantly affects the absorption effect.These findings underscore the potential of terahertz spectroscopy in conjunction with principal component analysis to qualitatively assess the similarities and differences between coal samples,thus offering novel insights for the online monitoring of diverse coal types and qualities.
文摘Parametric down-conversion is a useful method to obtain non-classical state in quantum optics. （1） An analytical solution to the Fokker-Planck equation of non-degenerate optical parametric amplification （NOPA） for generation of squeezed light is presented. The maximum intra-cavity compression of squeezed light derived from the analytical solution is 1/16 （vacuum fluctuations 1/4）. To compare it with the previous 1/8 of degenerate optical parametric amplification （DOPA）, it seems that squeezing for NOPA is superior to DOPA.
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supported by the Scientific and Technological Innovation Program of Higher Eduation Institutions in Shanxi Province,China (Grant Nos. 2020L0471and 2020L0472)the National Natural Science Foundation of China (Grant Nos. 11847128, 11775040, and 11971277)the Science Technology Plan Project of Datong City,China (Grant No. 2020153)。
文摘The perfect photon absorption is studied in a cavity quantum electrodynamics(CQED) system, in which an optical parameter amplifier(OPA) is coupled to the cavity mode. This makes it possible to control the optical phase to realize the perfect photon absorption. It is found that in the presence of one and two injected fields, the perfect photon absorption is present in these two cases and can be controlled by adjusting the parametric phase. Moreover, different from the previous predictions of perfect photon absorption in atomic CQED systems, the perfect photon absorption can be changed significantly by the relative phase. Our work provides a new platform to use the parametric processes to make an available way to control the behaviors of photons and to take advantage of the optical phase to achieve the perfect photon absorption.
文摘The optical parameters for three samples of intrinsic, doped Si and doped Mg (Al x Ga 1- x ) y In 1- y P prepared by the MOCVD on GaAs substrate were measured by using ellipsometry and were calculated by the two-layer absorption film model. The results obtained were discussed. The grown rates and thickness of oxidic layer on the intrinsic (Al x Ga 1- x ) y In 1- y P surface exposed in the atmosphere were studied. A linear dependence of oxidic layer thickness on the time was obtained.
文摘Dy^3＋-doped borate glasses （LBLB） with high effective visible fluorescence emission were synthesized. The absorption spectrum and fluorescence spectrum of this glass were measured and analyzed. By using J-O theory, the oscillator strengths for some absorption transitions were calculated according to the absorption spectra. The intensity parameters Ω1 （t = 2, 4, 6） of Dy^3＋ were determined by using a least-squares fitting approach, and the values are 4.04 × 10^-20, 1.30 × 10^-20 and 1.82 × 10^-20 cm, respectively. The root-mean-square deviation δrma was calculated. Under UV light excitation, Dy^3＋-doped borate glasses （LBLB） emit intense yellowish white lights. The excitation spectrum indicates that argon laser is the effective excitation source in Dy^3＋-doped LBLB glasses
文摘Optical parametric lasers widely using in many science and technology field owin g to its merit of wide tunable spectrum range.But common optical parametric lase rs achieve tune by change of angel or temperature.The tune velocity and tune pre cision of these tune modes does not satisfy in many applications.The reporting i nto an optical parametric laser which achieve tune by electooptic effect,that have got speediness tune velocity and relatively quite tune precision. The optical parametric device design based on parametric fluorescent produce thr ough sum frequency phase matching in nonlinear optical crystals.It is a tune pr o cess of refractive index about parametric and pump light in nonlinear optical cr ystals namely.But refractive index of nonlinear optical crystals possess electro o ptic effect can change via apply transformable electro field.This change only w a nts a time of ns grade.So optical parametric device with nonlinear optical cryst als possess suitability electrooptic effect can realize speediness tune in princ iple.The idea about design on the recommended device here is somewhat as follows .The tune model is phase tuning.To strive increase the effect of electro optic f unction under keep immovable polarization directions of 3 wavelength in the opti cal parametric process,to strive convenient for apply electro field,the electro field is only sensitive for a refractive index of some wavelength in specificall y spectrum region.The principium examination has showed that the idea is reasona ble.Our count have show also that its tune precision same as expectance.
基金Project supported by the Fundamental Research Funds for the Central Universities(Grant No.2010LKWL07)the National Basic Research Program of China(Grant No.2010CB226805)
文摘This paper reports that a series of Nd3＋：Er3＋：yb3＋ co-doped borosilicate glasses have been prepared and their absorption spectra measured. The J-O intensity parameters Ωk （k = 2, 4, 6）, spontaneous radiative lifetime Trad, spontaneous transition probability A, fluorescence branching ratio β and oscillator strength fed of the Nd3＋ ions at room temperature are calculated based on Judd-Ofelt （J-O） theory. The temperature dependence of the up-conversion photoluminescence characteristics in a Nd3＋：Er3＋：Yb3＋ co-doped sample is studied under a 978 nm semiconductor laser excitation, and the energy transfer mechanisms among Yb3＋, Er3＋ and Nd3＋ ions are analysed. The results show that the J-O intensity parameters Ω2 increase when the Nd3＋ concentration of the Nd3＋：Er3＋：yb3＋ co-doped borosilicate glasses increases. The possibility of spontaneous transition is small and lifetimes are long at levels of 4F5/2 and 4F3/2. The intensity of Nd3＋ emissions at 595, 691, 753, 813 and 887 nm axe markedly enhanced when the sample temperature exceeds 400 K. The reasons being the cooperation of the secondary sensitization from Era＋ to Nd3＋ and the contribution of a multi-phonon.
文摘Single crystal Ga X In 1-X As films have grown up on GaAs(100) substrate at 375℃ and on InP(100) substrate at 390℃, respectively, by the method of rf sputtering with using undoped GaInAs polycrystal as target. However, on Si(100) or Si(111) substrates at 260～390℃, even at 465℃, only polycrystalline films were obtained. In addition, the structure, composition, electrical characteristic and optical properties of the Ga X In 1-X As films were investigated using X ray diffraction (XRD), reflection of high energy electron diffraction (RHEED), energy dispersion analyzer of X ray (EDAX), Hall measurements and spectroscopic ellipsometry.
文摘A vectorial optical field generator(VOF-Gen) based on two reflective phase-only liquid crystal spatial light modulators enables the creation of an arbitrary optical complex field. In this work, the capabilities of the VOF-Gen in terms of manipulating the spatial distributions of phase, amplitude, and polarization are experimentally demonstrated by generating a radially polarized optical field consisted of five annular rings, the focusing properties of which are also numerically studied with vectorial diffraction theory. By carefully adjusting the relative amplitude and phase between the adjacent rings, an optical needle field with purely longitudinal polarization can be produced in the focal region of a high numerical aperture lens. The versatile method presented in this work can be easily extended to the generation of a vectorial optical field with any desired complex distributions.
基金The authors are grateful to V.B.Shirokov for conducting studies of the films surface by the AFM method.This work was carried out within the framework of the State Assignment of the SSC RAS(Theme of State Registration No.01201354247).
文摘The research findings of the phase composition,nanostructure and optical properties of strontium-barium niobate thin films are discussed.Sr_(x)Ba_(1−x)Nb_(2)O_(6)nanosized films(x=0.5 and 0.61)were characterized by XRD,SEM and AFM studies.Reflective multi-angle ellipsometry and spectrophotometry were used to determine the optical parameters(refractive index,its dispersion,and thickness of the damaged surface layer)of thin films.It was shown that SBN-50 and SBN-61 thin films were grown c-oriented on Al_(2)O_(3)(0001)and heteroepitaxial on MgO(001)substrates.The increase of refractive index,approaching its maximum value in the bulk material for a given composition as the film thickness increases,is observed.
文摘Background Optical coherence tomography （OCT） is a high resolution noncontact imaging modality which can quantitatively detect the optic disc and retinal structure.This study was designed to evaluate the diagnostic capability of parameters of the optic disc, retinal nerve fiber layer thickness, and ganglion cell complex （GCC） using a new technology called Fourier-domain OCT （FD-OCT） for early primary open angle glaucoma （POAG） patients.Methods Two groups of patients, early perimetric damage POAG and normal subjects were included in this observational cross-sectional study.All patients underwent FD-OCT and visual field examination in addition to full ophthalmic examinations.Receiver operating characteristic curves （ROC） were studied for all parameters.The sensitivity and specificity for distinguishing between normal and early glaucomatous eyes, the areas under the receiver operating characteristic curves （AROC） and positive, negative likelihood ratios were evaluated for all the single parameters and selected combined parameters using arbitrary cutoffs.Results Thirty-four eyes of 34 early POAG patients and 42 eyes of 42 normal subjects were analyzed.Cup/disc （C/D）vertical ratio presented the best sensitivity and positive likelihood ratio for selected specificities （95% and 85%） which were 79.4% and 88.2%, 33.4 and 7.4, respectively.Among all single parameters, the C/D vertical ratio demonstrated the highest AROC which was at 0.930.The average thickness of circumpapillary RNFL on 3.45 mm showed the highest AROC among all of the peripapillary RNFL parameters.The sensitivity at selected specificity and AROC of GCC were not as high as C/D vertical ratio and RNFL AT on 3.45 mm.When the C/D vertical ratio, RNFL AT on 3.45 mm, and rim area were combined using a logistical diagnostic model, the AROC was raised to 0.949 but not significantly different from the top single parameter, C/D vertical ratio.Conclusions The key parameters obtained by FD-OCT were able to show the significant differences of optic discs,thickness of RNFL and GCC between POAG patients and normal subjects.According to sensitivity, specificity, likelihood ratio and AROC, the top three parameters from FD-OCT for early diagnosis of POAG were C/D vertical ratio, RNFL AT on 3.45 mm, and the rim area.
基金supported by the National Natural Science Foundation of China under Grant No. 11178004
文摘A real-time method for measuring atmospheric parameters based on co-processor field-programmable gate array （FPGA） and main processor digital signal processing （DSP） is proposed for ground-based telescopes with adaptive optics （AO） systems. Coherence length, outer scale, average wind speed, and coherence time are estimated according to closed-loop data on the residual slopes and the corrected voltages of AO systems. This letter introduces the principle and architecture design of the proposed method, which is successfully applied in the 127-element AO system of the 1.8-m telescope of Yunnan Astronomical Observatory. The method enables real-time atmospheric observations with the same object and path of the AO system. This method is also applicable to extended objects.
基金partially funded by the Tunisian Ministry of Higher Education and Scientific Research,the Spanish Programa Nacional de Materiales through project MAT2014-51778-C2-2-Rby the Universitat de Girona contract No.MPCUd G2016/059.Dfinancial support of the Tunisian Ministry of Higher Education and Scientific Research
文摘The new organic-inorganic compound, [C_6H_7N_2O_2]_3TeCl_5·2Cl was synthesized and its structure was determined at room temperature in the triclinic system （P^-1） with the following parameters： a = 10.5330（11） ？, b = 10.6663（11） ？, c = 15.9751（16）？, α = 82.090（2）°, β = 71.193（2）°, γ = 68.284（2）°and Z = 2. The final cycle of refinement led to R = 0.057 and Rw = 0.149. The crystal structure was stabilized by an extensive network of N--H···Cl and non-classical C--H···Cl hydrogen bonds between the cation and the anionic group. Several thermal analysis techniques such as thermogravimetric analysis, differential scanning calorimetric analysis and evolved gas analysis were used. We used isoconversional kinetics methods to determine the kinetics parameters. We observe that the decomposition of [C_6H_7N_2O_2]_3TeCl_5·2Cl entails the formation hydrochloric acid of nitroaniline as volatiles. The infrared spectra were recorded in the4000–400 cm^（-1）frequency region. The Raman spectra were recorded in the external region of the anionic sublattice vibration 50–1500 cm^（-1）. The optical band gap was calculated from the UV-Vis absorbance spectra using classical Tauc relation which was found to be 3.12 and 3.67 eV.
