Superconducting nanowire single-photon detectors （SNSPDs） with a composite optical structure composed of phase-grating and optical cavity structures are designed to enhance both the system detection efficiency and t...Superconducting nanowire single-photon detectors （SNSPDs） with a composite optical structure composed of phase-grating and optical cavity structures are designed to enhance both the system detection efficiency and the response bandwidth. Numerical simulation by the finite-difference time-domain method shows that the photon absorption capacity of SNSPDs with a composite optical structure can be enhanced significantly by adjusting the parameters of the phase-grating and optical cavity structures at multiple frequency bands. The absorption capacity of the superconducting nanowires reaches 70%, 72%, 60.73%, 61.7%, 41.2%, and 46.5% at wavelengths of 684, 850, 732, 924, 1256, and 1426nm, respectively. The use of a composite optical structure reduces the total filling factor of superconducting nanowires to only 0.25, decreases the kinetic inductance of SNSPDs, and improves the count rates.展开更多
Purpose The Einstein Probe(EP)satellite is a space X-ray satellite for time-domain astronomy and high-energy astrophysics.The precision control of the optical structure directly affects the imaging quality and positio...Purpose The Einstein Probe(EP)satellite is a space X-ray satellite for time-domain astronomy and high-energy astrophysics.The precision control of the optical structure directly affects the imaging quality and positioning accuracy of the Follow-up X-ray Telescope(FXT),playing a crucial role in achieving the on-orbit scientific objectives of the FXT.Higher positioning accuracy makes it easier to identify corresponding bodies for the discovery and positioning of transient sources.Accurate positioning is beneficial for follow-up observations in other bands,such as optical spectroscopy.Methods This article mainly introduces the precision control methods and processes of the FXT optical structure,which have been tested and verified through satellite test.The on-orbit source positioning accuracy of the FXT telescope is within 20 arcseconds(90% confidence level),meeting the requirements of the FXT mission.Results and Conclusion To ensure the accuracy of the EP satellite’s FXT optical structure,measures such as component processing control,installation control,and posttest adjustments are taken on the ground to ensure that the detector mounting position,optical axis deviation,and other precision indicators before and after the satellite lever test meet the design requirements.After a successful launch,through on-orbit calibration,the FXT-A and FXT-B optical axis pointing direction deviation is 39 arcseconds,and the source positioning error is better than 3'' at 68% confidence level.FXT optical structure meets all the requirements from design,processing,installation,etc.,successfully meeting scientific needs.展开更多
A woofer–tweeter adaptive optical structured illumination microscope(AOSIM) is presented. By combining a low-spatial-frequency large-stroke deformable mirror(woofer) with a high-spatial-frequency low-stroke deformabl...A woofer–tweeter adaptive optical structured illumination microscope(AOSIM) is presented. By combining a low-spatial-frequency large-stroke deformable mirror(woofer) with a high-spatial-frequency low-stroke deformable mirror(tweeter), we are able to remove both large-amplitude and high-order aberrations. In addition, using the structured illumination method, as compared to widefield microscopy, the AOSIM can accomplish highresolution imaging and possesses better sectioning capability. The AOSIM was tested by correcting a large aberration from a trial lens in the conjugate plane of the microscope objective aperture. The experimental results show that the AOSIM has a point spread function with an FWHM that is 140 nm wide(using a water immersion objective lens with NA=1.1) after correcting a large aberration(5.9 μm peak-to-valley wavefront error with 2.05 μm RMS aberration). After structured light illumination is applied, the results show that we are able to resolve two beads that are separated by 145 nm, 1.62× below the diffraction limit of 235 nm. Furthermore, we demonstrate the application of the AOSIM in the field of bioimaging. The sample under investigation was a green-fluorescentprotein-labeled Drosophila embryo. The aberrations from the refractive index mismatch between the microscope objective, the immersion fluid, the cover slip, and the sample itself are well corrected. Using AOSIM we were able to increase the SNR for our Drosophila embryo sample by 5×.展开更多
The electronic structures and optical properties of the [llO]-oriented Sil-xGex nanowires （NWs） passivated with different functional groups （-H, -F and-OH） are investigated by using first-principles calculations. ...The electronic structures and optical properties of the [llO]-oriented Sil-xGex nanowires （NWs） passivated with different functional groups （-H, -F and-OH） are investigated by using first-principles calculations. The results show that surface passivation influences the characteristics of electronic band structures significantly： the band gap widths and types （direct or indirect） of the Si1-xGe, NWs with different terminators show complex and robust variations, and the effective masses of the electrons in the NWs can be modulated dramatically by the terminators. The study of optical absorption shows that the main peaks of the parallel polarization component of Si1-x Gex NWs passivated with the functional groups exhibit prominent changes both in height and position, and are red-shifted with respect to those of corresponding pure Si NWs, indicating the importance of both the terminators and Ge concentrations. Our results demonstrate that the electronic and optical properties of Si1-xGex NWs can be tuned by utilizing selected functional groups as well as particular Ge concentrations for customizing purposes.展开更多
A new zero-dimensional（0D） thioborate Ba_9B_3GaS_（15） has been discovered by conventional high-temperature solid-state reaction. The compound crystallizes in orthorhombic space group Pbca with a = 8.4759（8）,b = ...A new zero-dimensional（0D） thioborate Ba_9B_3GaS_（15） has been discovered by conventional high-temperature solid-state reaction. The compound crystallizes in orthorhombic space group Pbca with a = 8.4759（8）,b = 22.266（2）,c = 31.426（3） ？,V = 5931（2） ？~3,Z = 8,Mr = 1819.11,Dc = 4.075 g/cm3,μ = 13.684 mm^（-1）,F（000） = 6320,S = 1.034,（Δρ）max = 5.039,（Δρ）min = –5.409 e/？~3,the final R = 0.0362 and w R = 0.1053 for 19243 observed reflections with I 〉 2σ（I）. The structure is constructed by discrete [BS_3]^（3–） trigonal planes and isolated [GaS_4]^（5–） tetrahedra with Ba^（2＋） and isolated S^（2–） filled among them. The UV-Vis-near-IR spectrum reveals a wide band gap of 3.15 eV that agrees with the electronic structure calculation.展开更多
Growth of ln0.52Al0.48As epitaxial layers on lnP(100) substrates by molecular beam epitaxy at a wide range of arsenic overpressures (V/III flux ratios from 30 to 300) has been carried out. Analysis performed using low...Growth of ln0.52Al0.48As epitaxial layers on lnP(100) substrates by molecular beam epitaxy at a wide range of arsenic overpressures (V/III flux ratios from 30 to 300) has been carried out. Analysis performed using low-temperature photoluminescence (PL) and double-axis X-ray diffraction (XRD) shows a strong and prominent dependence of the PL and XRD linewidths on the V/III flux ratio. Under our growth conditions, both the PL and XRD linewidths exhibit a minimum point at a V/III flux ratio of 150 which corresponds to a maximum in the PL intensity and XRD intensity ratio. Flux ratios exceeding 150 result in an increase in both the PL and XRD linewidths corresponding to a reduction in their associated intensities. Room temperature Raman scattering measurements show a narrowing in the lnAs-like and AlAs-like longitudinal-optic (LO)phonon linewidths which broaden at high flux ratios, while the LO phonon frequencies exhibit a gradual reduction as the flux ratio is increased. PL spectra taken at increasing temperatures show a quenching of the main emission peak followed by the evolution of a broad lower energy emission which is possibly associated with deep lying centres. This effect is more prominent in samples grown at lower V/III flux ratios. Hall effect measurements show a gradual reduction in the mobility in correspondence to an increase in the electron concentration as the flux ratio is increased.展开更多
Correlation between the belieal structure and optical activity of two derivatives of R(+)- 1, 1'-binaphthyl-2,2'-diol was derived from a study of their optical rotations, CD curves and Xray crystal structures.
Using transmission electron microscopy （TEM） and x-ray diffraction analysis, we have studied the structural and morphological evolution of highly Er/Yb co-doped A1203 films in the temperature range from 600℃-900℃....Using transmission electron microscopy （TEM） and x-ray diffraction analysis, we have studied the structural and morphological evolution of highly Er/Yb co-doped A1203 films in the temperature range from 600℃-900℃. By comparison with TEM observation, the annealing behaviours of photoluminescence （PL） emission and optical loss were found to have relation to the structure and morphology. The increase of PL intensity and optical loss above 800℃ might result from the crystallization of amorphous Al2O3 films. Based on the study on the structure and morphology, a rate equation propagation model of a multilevel system was used to calculate the optical gains of Er-doped Al2O3 planar waveguide amplifiers involving the variation of PL efficiency and optical loss with annealing temperature. It was found that the amplifiers had an optimized optical gain at the temperature corresponding to the minimum of optical loss, rather than at the temperature corresponding to the maximum of PL efficiency, suggesting that the optical loss is a key factor for determining the optical gain of an Er-doped Al2O3 planar waveguide amplifier.展开更多
Optical gains of type-Ⅱ In Ga As/Ga As Bi quantum wells（QWs） with W, N, and M shapes are analyzed theoretically for near-infrared laser applications. The bandgap and wave functions are calculated using the self-con...Optical gains of type-Ⅱ In Ga As/Ga As Bi quantum wells（QWs） with W, N, and M shapes are analyzed theoretically for near-infrared laser applications. The bandgap and wave functions are calculated using the self-consistent k·p Hamiltonian, taking into account valence band mixing and the strain effect. Our calculations show that the M-shaped type-Ⅱ QWs are a promising structure for making 1.3 um lasers at room temperature because they can easily be used to obtain 1.3 um for photoluminescence with a proper thickness and have large wave-function overlap for high optical gain.展开更多
We report a study of the electronic structure and optical properties of uranium dioxide （U02） based on the ab-initio density-functional theory and using the generalized gradient approximation. To correctly describe ...We report a study of the electronic structure and optical properties of uranium dioxide （U02） based on the ab-initio density-functional theory and using the generalized gradient approximation. To correctly describe the strong correlation between 5 f electrons of a uranium atom, we employ the on-site Hubbard U correction term and optimize the correlation parameter of the bulk uranium dioxide. Then we give the structural and electronic properties of the ground state of uranium dioxide. Based on the accurate electronic structure, we calculate the complex dielectric function of UO2 and the related optieM properties, such as reflectivity, refractive index, extinction index, energy loss spectra, and absorption coefficient.展开更多
A method for the analysis of the relationship between the helical structure and optical activity was proposed by the study of the conformations and X-ray diffraction structures of some cyclic esters prepared by esteri...A method for the analysis of the relationship between the helical structure and optical activity was proposed by the study of the conformations and X-ray diffraction structures of some cyclic esters prepared by esterification of L-(-)-2.3-O-methylidene threitol and L-(+)-2,3-O-isopropplidene threitol with alkanedioyl dichlorides and o-,m-,and p-phthaloyl dichlorides.展开更多
Semiconductor nanocrystals directly grown on the conducting metal can lower the contact resistance and can benefit the electron transfer between the semiconductor and the metal. In the present work, CdO nanocrystals a...Semiconductor nanocrystals directly grown on the conducting metal can lower the contact resistance and can benefit the electron transfer between the semiconductor and the metal. In the present work, CdO nanocrystals are directly synthesized on the conducting Cd foil through a simple solvothermal method. Cd foil is used as the Cd2＋ source and the substrate. The average size of CdO nanocrystals is -23.1 nm by analyzing the XRD data. Moreover the growth mechanism is discussed. A hierarchic structure characterized by the nano rods and nano particles in the top and bottom layers, respectively, can be observed. From the UV-vis absorption analyzed by Taucs relation, the two different optical band gaps are obtained. The photoluminescence spectrum is obtained and studied.展开更多
A novel carbazole derivative 2-cyano-3-（9-ethyl-9H-carbazol-3-yl）-acrylic acid ethyl ester（L） was designed and synthesized through Vilsmeier and Knoevenagelreactions, which was characterized by FT-IR, ~1H NMR and1...A novel carbazole derivative 2-cyano-3-（9-ethyl-9H-carbazol-3-yl）-acrylic acid ethyl ester（L） was designed and synthesized through Vilsmeier and Knoevenagelreactions, which was characterized by FT-IR, ~1H NMR and13 C NMR spectra. The crystal of L crystallizes in the monoclinic system, space group P21/c with a = 10.8298（15）, b = 13.4660（19）, c = 15.4358（16） ？, β = 131.214（6）o, V = 1693.4（4） ？~3, Z = 4, Dc = 1.249 g/cm^3, Mr = 318.36, μ = 0.082 mm-1, F（000） = 672, completeness to theta was 99.9% and GOOF = 1.091.Rint = 0.0338, R（I 〉2σ（I）） = 0.0631, w R（I 〉 2σ（I）） = 0.1861, R（all data） = 0.1027 andw R（all data） = 0.2105. There were three types of weak intermolecular interactions（C（8）–H（8）···N（2）, C（14）–H（14）···O（2） and C（20B）– H（20B）···π）among the adjacent molecules to construct a three-dimensional single crystal. The UV-Vis spectra, fluorescence emission and time-dependent density functional theory（TD-DFT） calculation of L were studied and the results revealedthe existence of intramolecular charge transfer（ICT） process of L molecule. The optical properties indicated that it can be used as a potential candidate in the application oforganic light emitting diodes（OLEDs）.展开更多
The phase diagram of HfO_2–TiO_2 system shows that when Ti content is less than 33.0 mol%, HfO_2–TiO_2 system is monoclinic; when Ti content increases from 33.0 mol% to 52.0 mol%, it is orthorhombic; when Ti content...The phase diagram of HfO_2–TiO_2 system shows that when Ti content is less than 33.0 mol%, HfO_2–TiO_2 system is monoclinic; when Ti content increases from 33.0 mol% to 52.0 mol%, it is orthorhombic; when Ti content reaches more than 52.0 mol%, it presents rutile phase. So, we choose the three phases of HfO_2–TiO_2 alloys with different Ti content values. The electronic structures and optical properties of monoclinic, orthorhombic and rutile phases of HfO_2–TiO_2 alloys are obtained by the first-principles generalized gradient approximation（GGA） ＋U approach, and the effects of Ti content and crystal structure on the electronic structures and optical properties of HfO_2–TiO_2 alloys are investigated. By introducing the Coulomb interactions of 5 d orbitals on Hf atom（U_1~d）, those of 3 d orbitals on Ti atom（U_2~d）, and those of 2 p orbitals on O atom（Up） simultaneously, we can improve the calculation values of the band gaps, where U_1~d, U_2~d, and Up values are 8.0 eV, 7.0 eV, and 6.0 eV for both the monoclinic phase and orthorhombic phase, and 8.0 eV, 7.0 eV, and 3.5 eV for the rutile phase. The electronic structures and optical properties of the HfO_2–TiO_2 alloys calculated by GGA ＋U_1~d（U_1~d= 8.0 eV） ＋U_2~d（U_2~d= 7.0 eV） ＋U^p（U^p= 6.0 eV or 3.5 eV） are compared with available experimental results.展开更多
This paper proposes k-regular and k-connected(k&k) structure against multifaults in ultra-high capacity optical networks.Theoretical results show that pre-configured k&k structure can reach the lower bound on ...This paper proposes k-regular and k-connected(k&k) structure against multifaults in ultra-high capacity optical networks.Theoretical results show that pre-configured k&k structure can reach the lower bound on logical redundancy.The switching time of k&k protection structure is as quickly as ringbased protection in SDH network.It is the optimal protection structure in ultra-high capacity optical networks against multi-faults.We develop the linear programming model for k&k structure and propose a construction method for k&k structure design.Simulations are conducted for spare spectrum resources effi ciency of the pre-confi gured k&k structure under multi-faults on representative COST239 and NSFnet topologies.Numerical results show that the spare spectrum resources efficiency of k&k structure can reach the lower bound on logical redundancy in static networks.And it can largely improve spare spectrum resources effi ciency compared with p-cycles based protection structure without reducing protection effi ciency under dynamic traffi cs.展开更多
The article entitled with OptoGPT:A foundation model for inverse design in optical multilayer thin film structures1,with doi:10.29026/oea.2024.240062,published in No.7,Vol.7,2024 of Opto-Electronic Advances,has attrac...The article entitled with OptoGPT:A foundation model for inverse design in optical multilayer thin film structures1,with doi:10.29026/oea.2024.240062,published in No.7,Vol.7,2024 of Opto-Electronic Advances,has attracted attention from many researchers.As a result,the authors received many requests on the possibility sharing their code,model,and dataset in the mentioned work.To facilitate the needs of the research community,the authors decide to make the code,model,and datasets of OptoGPT public,enabling broader utilization and further development of enhanced models.展开更多
Single mode-multimode-single mode （SMS） sensor is widely used for parameters measurement, such as bending, dis-placement, temperature, strain, refractive index, etc. Generally, SMS sensor has advantages of simpl...Single mode-multimode-single mode （SMS） sensor is widely used for parameters measurement, such as bending, dis-placement, temperature, strain, refractive index, etc. Generally, SMS sensor has advantages of simple structure, low cost and easy layout, therefore it has become a research hotspot in recent years. In this paper, the multimode fiber with large core is used for manufacturing SMS structure with high sensitivity. Firstly, the multimode fiber with core/cladding diameters of 105/ 125 jitm has access to the system by means of single mode optical fiber. Secondly, SMS device structure is manufactured by welding the eccentric shaft of multimode optical fiber. Afterwards, mode interference effect and spectral response characteristics of the structure of single mode-multimode-single mode optical fiber are analyzed theoretically. Finally, with the help of a wide spectrum light source and a spectrum analyzer, the transmission spectra characteristics of SMS optical fiber with strain is tested. By observing the curve that the wave changes with stress, the sensitivity is calculated and it is consistent with theoretical value .展开更多
An investigation of structural stabilities, electronic and optical properties of SrF2 under high pressure is conducted using a first-principles calculation based on density functional theory （DFT） with the plane wav...An investigation of structural stabilities, electronic and optical properties of SrF2 under high pressure is conducted using a first-principles calculation based on density functional theory （DFT） with the plane wave basis set as implemented in the CASTEP code. Our results predict that the second high-pressure phase of SrF2 is of a Ni2In- type structure, and demonstrate that the sequence of the pressure-induced phase transition of SrF2 is the fluorite structure （Fm3m） to the PbC12-type structure （Pnma）, and to the Ni2In-type phase （P63/mmc）. The first and second phase transition pressures are 5. 77 and 45.58 GPa, respectively. The energy gap increases initially with pressure in the Fm3m, and begins to decrease in the Pnma phases at 30 GPa. The band gap overlap metallization does not occur up to 210 GPa. The pressure effect on the optical properties is discussed.展开更多
Following are the comments for the queries raised by Prof. Pawel E. Tomaszewski on our published paper entitled ＂Structural, Optical, and Electrical Properties of Zn-Doped CdO Thin Films Fabricated by a Simplified Sp...Following are the comments for the queries raised by Prof. Pawel E. Tomaszewski on our published paper entitled ＂Structural, Optical, and Electrical Properties of Zn-Doped CdO Thin Films Fabricated by a Simplified Spray Pyrolysis Technique＂ by K. Usharani and A.R. Balu published in Acta Metall. Sin.展开更多
The present paper reported the structural and luminescent properties of Eu^（2＋） and Nd^（3＋） doped CaAl_2O_4 phosphor. The samples were prepared by microwave-assisted chemical co-precipitation（MA-CCP）, a synthe...The present paper reported the structural and luminescent properties of Eu^（2＋） and Nd^（3＋） doped CaAl_2O_4 phosphor. The samples were prepared by microwave-assisted chemical co-precipitation（MA-CCP）, a synthesis technique which is suitable for small and uniform particle that could be used directly without grinding. The effects of different microwave temperatures on structure and photoluminescence behavior were studied. Formation of a phosphor and phase purity were confirmed by X-ray diffraction technique（XRD） with variable microwave temperatures. XRD analysis showed that the phosphors prepared by MA-CCP method at the temperature of 750, 900oC, respectively and solid-state reaction（SSR） method at 1300oC consisted of impurities. Commission Internationale de L＇Eclairage（CIE） color coordinates of CaAl_2O_4：Eu^（2＋）,Nd^（3＋） were suitable as blue light emitting phosphor. Excitation and emission peaks of the samples prepared by different methods in this study were almost the same. The images of SEM showed that the size of the phosphors prepared by MA-CCP method reached a submicrometer.展开更多
基金Supported by the National Basic Research Program of China under Grant Nos 2011CBA00100 and 2011CBA00200the National Natural Science Foundation of China under Grant Nos 11227904 and 61101012+1 种基金the National High-Technology ResearchDevelopment Program of China under Grant No 2011AA010204the Jiangsu Key Laboratory of Advanced Techniques for Manipulating Electromagnetic Waves
文摘Superconducting nanowire single-photon detectors （SNSPDs） with a composite optical structure composed of phase-grating and optical cavity structures are designed to enhance both the system detection efficiency and the response bandwidth. Numerical simulation by the finite-difference time-domain method shows that the photon absorption capacity of SNSPDs with a composite optical structure can be enhanced significantly by adjusting the parameters of the phase-grating and optical cavity structures at multiple frequency bands. The absorption capacity of the superconducting nanowires reaches 70%, 72%, 60.73%, 61.7%, 41.2%, and 46.5% at wavelengths of 684, 850, 732, 924, 1256, and 1426nm, respectively. The use of a composite optical structure reduces the total filling factor of superconducting nanowires to only 0.25, decreases the kinetic inductance of SNSPDs, and improves the count rates.
基金supported by the Strategic Priority Research Program on Space Science,the Chinese Academy of Sciences(Grant No.XDA 15310103).
文摘Purpose The Einstein Probe(EP)satellite is a space X-ray satellite for time-domain astronomy and high-energy astrophysics.The precision control of the optical structure directly affects the imaging quality and positioning accuracy of the Follow-up X-ray Telescope(FXT),playing a crucial role in achieving the on-orbit scientific objectives of the FXT.Higher positioning accuracy makes it easier to identify corresponding bodies for the discovery and positioning of transient sources.Accurate positioning is beneficial for follow-up observations in other bands,such as optical spectroscopy.Methods This article mainly introduces the precision control methods and processes of the FXT optical structure,which have been tested and verified through satellite test.The on-orbit source positioning accuracy of the FXT telescope is within 20 arcseconds(90% confidence level),meeting the requirements of the FXT mission.Results and Conclusion To ensure the accuracy of the EP satellite’s FXT optical structure,measures such as component processing control,installation control,and posttest adjustments are taken on the ground to ensure that the detector mounting position,optical axis deviation,and other precision indicators before and after the satellite lever test meet the design requirements.After a successful launch,through on-orbit calibration,the FXT-A and FXT-B optical axis pointing direction deviation is 39 arcseconds,and the source positioning error is better than 3'' at 68% confidence level.FXT optical structure meets all the requirements from design,processing,installation,etc.,successfully meeting scientific needs.
基金UC Office of the President(MR-15-327968)National Science Foundation(NSF)(1353461)National Institutes of Health(NIH)(R21MH101688)
文摘A woofer–tweeter adaptive optical structured illumination microscope(AOSIM) is presented. By combining a low-spatial-frequency large-stroke deformable mirror(woofer) with a high-spatial-frequency low-stroke deformable mirror(tweeter), we are able to remove both large-amplitude and high-order aberrations. In addition, using the structured illumination method, as compared to widefield microscopy, the AOSIM can accomplish highresolution imaging and possesses better sectioning capability. The AOSIM was tested by correcting a large aberration from a trial lens in the conjugate plane of the microscope objective aperture. The experimental results show that the AOSIM has a point spread function with an FWHM that is 140 nm wide(using a water immersion objective lens with NA=1.1) after correcting a large aberration(5.9 μm peak-to-valley wavefront error with 2.05 μm RMS aberration). After structured light illumination is applied, the results show that we are able to resolve two beads that are separated by 145 nm, 1.62× below the diffraction limit of 235 nm. Furthermore, we demonstrate the application of the AOSIM in the field of bioimaging. The sample under investigation was a green-fluorescentprotein-labeled Drosophila embryo. The aberrations from the refractive index mismatch between the microscope objective, the immersion fluid, the cover slip, and the sample itself are well corrected. Using AOSIM we were able to increase the SNR for our Drosophila embryo sample by 5×.
基金Supported by the National Natural Science Foundation of China under Grant No 11004142the Program for New Century Excellent Talents in University under Grant No 11-035the Project Sponsored by the Scientific Research Foundation for ROCS of the Ministry of Education of China
文摘The electronic structures and optical properties of the [llO]-oriented Sil-xGex nanowires （NWs） passivated with different functional groups （-H, -F and-OH） are investigated by using first-principles calculations. The results show that surface passivation influences the characteristics of electronic band structures significantly： the band gap widths and types （direct or indirect） of the Si1-xGe, NWs with different terminators show complex and robust variations, and the effective masses of the electrons in the NWs can be modulated dramatically by the terminators. The study of optical absorption shows that the main peaks of the parallel polarization component of Si1-x Gex NWs passivated with the functional groups exhibit prominent changes both in height and position, and are red-shifted with respect to those of corresponding pure Si NWs, indicating the importance of both the terminators and Ge concentrations. Our results demonstrate that the electronic and optical properties of Si1-xGex NWs can be tuned by utilizing selected functional groups as well as particular Ge concentrations for customizing purposes.
基金Supported by the National Natural Science Foundation of China(21233009,21225104,91422303,21301175 and 21171168)
文摘A new zero-dimensional（0D） thioborate Ba_9B_3GaS_（15） has been discovered by conventional high-temperature solid-state reaction. The compound crystallizes in orthorhombic space group Pbca with a = 8.4759（8）,b = 22.266（2）,c = 31.426（3） ？,V = 5931（2） ？~3,Z = 8,Mr = 1819.11,Dc = 4.075 g/cm3,μ = 13.684 mm^（-1）,F（000） = 6320,S = 1.034,（Δρ）max = 5.039,（Δρ）min = –5.409 e/？~3,the final R = 0.0362 and w R = 0.1053 for 19243 observed reflections with I 〉 2σ（I）. The structure is constructed by discrete [BS_3]^（3–） trigonal planes and isolated [GaS_4]^（5–） tetrahedra with Ba^（2＋） and isolated S^（2–） filled among them. The UV-Vis-near-IR spectrum reveals a wide band gap of 3.15 eV that agrees with the electronic structure calculation.
文摘Growth of ln0.52Al0.48As epitaxial layers on lnP(100) substrates by molecular beam epitaxy at a wide range of arsenic overpressures (V/III flux ratios from 30 to 300) has been carried out. Analysis performed using low-temperature photoluminescence (PL) and double-axis X-ray diffraction (XRD) shows a strong and prominent dependence of the PL and XRD linewidths on the V/III flux ratio. Under our growth conditions, both the PL and XRD linewidths exhibit a minimum point at a V/III flux ratio of 150 which corresponds to a maximum in the PL intensity and XRD intensity ratio. Flux ratios exceeding 150 result in an increase in both the PL and XRD linewidths corresponding to a reduction in their associated intensities. Room temperature Raman scattering measurements show a narrowing in the lnAs-like and AlAs-like longitudinal-optic (LO)phonon linewidths which broaden at high flux ratios, while the LO phonon frequencies exhibit a gradual reduction as the flux ratio is increased. PL spectra taken at increasing temperatures show a quenching of the main emission peak followed by the evolution of a broad lower energy emission which is possibly associated with deep lying centres. This effect is more prominent in samples grown at lower V/III flux ratios. Hall effect measurements show a gradual reduction in the mobility in correspondence to an increase in the electron concentration as the flux ratio is increased.
文摘Correlation between the belieal structure and optical activity of two derivatives of R(+)- 1, 1'-binaphthyl-2,2'-diol was derived from a study of their optical rotations, CD curves and Xray crystal structures.
基金Project supported by the National Natural Science Foundation of China （Grant No 50240420656）.
文摘Using transmission electron microscopy （TEM） and x-ray diffraction analysis, we have studied the structural and morphological evolution of highly Er/Yb co-doped A1203 films in the temperature range from 600℃-900℃. By comparison with TEM observation, the annealing behaviours of photoluminescence （PL） emission and optical loss were found to have relation to the structure and morphology. The increase of PL intensity and optical loss above 800℃ might result from the crystallization of amorphous Al2O3 films. Based on the study on the structure and morphology, a rate equation propagation model of a multilevel system was used to calculate the optical gains of Er-doped Al2O3 planar waveguide amplifiers involving the variation of PL efficiency and optical loss with annealing temperature. It was found that the amplifiers had an optimized optical gain at the temperature corresponding to the minimum of optical loss, rather than at the temperature corresponding to the maximum of PL efficiency, suggesting that the optical loss is a key factor for determining the optical gain of an Er-doped Al2O3 planar waveguide amplifier.
基金Supported by the National Basic Research Program of China under Grant No 2014CB643902the Key Program of Natural Science Foundation of China under Grant No 61334004+3 种基金the National Natural Science Foundation of China under Grant No 61404152the Strategic Priority Research Program of the Chinese Academy of Sciences under Grant No XDA5-1the Foundation of National Laboratory for Infrared Physics,the Key Research Program of the Chinese Academy of Sciences under Grant No KGZDEW-804the Creative Research Group Project of Natural Science Foundation of China under Grant No 61321492
文摘Optical gains of type-Ⅱ In Ga As/Ga As Bi quantum wells（QWs） with W, N, and M shapes are analyzed theoretically for near-infrared laser applications. The bandgap and wave functions are calculated using the self-consistent k·p Hamiltonian, taking into account valence band mixing and the strain effect. Our calculations show that the M-shaped type-Ⅱ QWs are a promising structure for making 1.3 um lasers at room temperature because they can easily be used to obtain 1.3 um for photoluminescence with a proper thickness and have large wave-function overlap for high optical gain.
基金Supported by the New Century Excellent Talents in University in Ministry of Education of China under Grant No NCET-09-0867
文摘We report a study of the electronic structure and optical properties of uranium dioxide （U02） based on the ab-initio density-functional theory and using the generalized gradient approximation. To correctly describe the strong correlation between 5 f electrons of a uranium atom, we employ the on-site Hubbard U correction term and optimize the correlation parameter of the bulk uranium dioxide. Then we give the structural and electronic properties of the ground state of uranium dioxide. Based on the accurate electronic structure, we calculate the complex dielectric function of UO2 and the related optieM properties, such as reflectivity, refractive index, extinction index, energy loss spectra, and absorption coefficient.
文摘A method for the analysis of the relationship between the helical structure and optical activity was proposed by the study of the conformations and X-ray diffraction structures of some cyclic esters prepared by esterification of L-(-)-2.3-O-methylidene threitol and L-(+)-2,3-O-isopropplidene threitol with alkanedioyl dichlorides and o-,m-,and p-phthaloyl dichlorides.
基金Supported by the National Natural Science Foundation of China under Grant Nos U1262112 and 51176205
文摘Semiconductor nanocrystals directly grown on the conducting metal can lower the contact resistance and can benefit the electron transfer between the semiconductor and the metal. In the present work, CdO nanocrystals are directly synthesized on the conducting Cd foil through a simple solvothermal method. Cd foil is used as the Cd2＋ source and the substrate. The average size of CdO nanocrystals is -23.1 nm by analyzing the XRD data. Moreover the growth mechanism is discussed. A hierarchic structure characterized by the nano rods and nano particles in the top and bottom layers, respectively, can be observed. From the UV-vis absorption analyzed by Taucs relation, the two different optical band gaps are obtained. The photoluminescence spectrum is obtained and studied.
基金Supported by the Natural Science Foundation of Anhui Province(1508085SMB208)the Educational Commission of Anhui Province(KJ2016A788)
文摘A novel carbazole derivative 2-cyano-3-（9-ethyl-9H-carbazol-3-yl）-acrylic acid ethyl ester（L） was designed and synthesized through Vilsmeier and Knoevenagelreactions, which was characterized by FT-IR, ~1H NMR and13 C NMR spectra. The crystal of L crystallizes in the monoclinic system, space group P21/c with a = 10.8298（15）, b = 13.4660（19）, c = 15.4358（16） ？, β = 131.214（6）o, V = 1693.4（4） ？~3, Z = 4, Dc = 1.249 g/cm^3, Mr = 318.36, μ = 0.082 mm-1, F（000） = 672, completeness to theta was 99.9% and GOOF = 1.091.Rint = 0.0338, R（I 〉2σ（I）） = 0.0631, w R（I 〉 2σ（I）） = 0.1861, R（all data） = 0.1027 andw R（all data） = 0.2105. There were three types of weak intermolecular interactions（C（8）–H（8）···N（2）, C（14）–H（14）···O（2） and C（20B）– H（20B）···π）among the adjacent molecules to construct a three-dimensional single crystal. The UV-Vis spectra, fluorescence emission and time-dependent density functional theory（TD-DFT） calculation of L were studied and the results revealedthe existence of intramolecular charge transfer（ICT） process of L molecule. The optical properties indicated that it can be used as a potential candidate in the application oforganic light emitting diodes（OLEDs）.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11672087,11502058,and 11402252)
文摘The phase diagram of HfO_2–TiO_2 system shows that when Ti content is less than 33.0 mol%, HfO_2–TiO_2 system is monoclinic; when Ti content increases from 33.0 mol% to 52.0 mol%, it is orthorhombic; when Ti content reaches more than 52.0 mol%, it presents rutile phase. So, we choose the three phases of HfO_2–TiO_2 alloys with different Ti content values. The electronic structures and optical properties of monoclinic, orthorhombic and rutile phases of HfO_2–TiO_2 alloys are obtained by the first-principles generalized gradient approximation（GGA） ＋U approach, and the effects of Ti content and crystal structure on the electronic structures and optical properties of HfO_2–TiO_2 alloys are investigated. By introducing the Coulomb interactions of 5 d orbitals on Hf atom（U_1~d）, those of 3 d orbitals on Ti atom（U_2~d）, and those of 2 p orbitals on O atom（Up） simultaneously, we can improve the calculation values of the band gaps, where U_1~d, U_2~d, and Up values are 8.0 eV, 7.0 eV, and 6.0 eV for both the monoclinic phase and orthorhombic phase, and 8.0 eV, 7.0 eV, and 3.5 eV for the rutile phase. The electronic structures and optical properties of the HfO_2–TiO_2 alloys calculated by GGA ＋U_1~d（U_1~d= 8.0 eV） ＋U_2~d（U_2~d= 7.0 eV） ＋U^p（U^p= 6.0 eV or 3.5 eV） are compared with available experimental results.
基金supported by the Major State Basic Research Development Program of China(973 Program)(Nos.2010CB328202,2010CB328204,and 2012CB315604)the HiTech Research and Development Program of China(863 Program)(Nos.2012AA01Z301,and 2012AA011302)+2 种基金the National Natural Science Foundation of China(No.60702005)the Beijing Nova Program(No.2011065)the Fundamental Research Funds for the Central Universities
文摘This paper proposes k-regular and k-connected(k&k) structure against multifaults in ultra-high capacity optical networks.Theoretical results show that pre-configured k&k structure can reach the lower bound on logical redundancy.The switching time of k&k protection structure is as quickly as ringbased protection in SDH network.It is the optimal protection structure in ultra-high capacity optical networks against multi-faults.We develop the linear programming model for k&k structure and propose a construction method for k&k structure design.Simulations are conducted for spare spectrum resources effi ciency of the pre-confi gured k&k structure under multi-faults on representative COST239 and NSFnet topologies.Numerical results show that the spare spectrum resources efficiency of k&k structure can reach the lower bound on logical redundancy in static networks.And it can largely improve spare spectrum resources effi ciency compared with p-cycles based protection structure without reducing protection effi ciency under dynamic traffi cs.
文摘The article entitled with OptoGPT:A foundation model for inverse design in optical multilayer thin film structures1,with doi:10.29026/oea.2024.240062,published in No.7,Vol.7,2024 of Opto-Electronic Advances,has attracted attention from many researchers.As a result,the authors received many requests on the possibility sharing their code,model,and dataset in the mentioned work.To facilitate the needs of the research community,the authors decide to make the code,model,and datasets of OptoGPT public,enabling broader utilization and further development of enhanced models.
基金National Natural Science Foundation of China(No.61405127)Shanxi Province Science Foundation for Youths(No.2014021023-1)+1 种基金Scientific and Technologial Innovation Programs of Higher Education Institutions in ShanxiProgram for the Top Young Academic Leaders of Higher Learning Institutions of Shanxi
文摘Single mode-multimode-single mode （SMS） sensor is widely used for parameters measurement, such as bending, dis-placement, temperature, strain, refractive index, etc. Generally, SMS sensor has advantages of simple structure, low cost and easy layout, therefore it has become a research hotspot in recent years. In this paper, the multimode fiber with large core is used for manufacturing SMS structure with high sensitivity. Firstly, the multimode fiber with core/cladding diameters of 105/ 125 jitm has access to the system by means of single mode optical fiber. Secondly, SMS device structure is manufactured by welding the eccentric shaft of multimode optical fiber. Afterwards, mode interference effect and spectral response characteristics of the structure of single mode-multimode-single mode optical fiber are analyzed theoretically. Finally, with the help of a wide spectrum light source and a spectrum analyzer, the transmission spectra characteristics of SMS optical fiber with strain is tested. By observing the curve that the wave changes with stress, the sensitivity is calculated and it is consistent with theoretical value .
基金Supported by the National Natural Science Foundation of China under Grant Nos 50771090 and 50821001, the National Basic Research Program of China under Grant No 2005CB724404, the Program for Changjiang Scholars and Innovative Team under Grant No IRT0650, and the Doctoral Foundation of Hebei Normal University of Science and Technology under Grant No 2008YB001.
文摘An investigation of structural stabilities, electronic and optical properties of SrF2 under high pressure is conducted using a first-principles calculation based on density functional theory （DFT） with the plane wave basis set as implemented in the CASTEP code. Our results predict that the second high-pressure phase of SrF2 is of a Ni2In- type structure, and demonstrate that the sequence of the pressure-induced phase transition of SrF2 is the fluorite structure （Fm3m） to the PbC12-type structure （Pnma）, and to the Ni2In-type phase （P63/mmc）. The first and second phase transition pressures are 5. 77 and 45.58 GPa, respectively. The energy gap increases initially with pressure in the Fm3m, and begins to decrease in the Pnma phases at 30 GPa. The band gap overlap metallization does not occur up to 210 GPa. The pressure effect on the optical properties is discussed.
文摘Following are the comments for the queries raised by Prof. Pawel E. Tomaszewski on our published paper entitled ＂Structural, Optical, and Electrical Properties of Zn-Doped CdO Thin Films Fabricated by a Simplified Spray Pyrolysis Technique＂ by K. Usharani and A.R. Balu published in Acta Metall. Sin.
基金Project supported by the Fundamental Research Funds for the Central Universities(JUSRP51723B)National Natural Science Foundation of China(51503083)+2 种基金Jiangsu Province Ordinary University Academic Degree Graduate Student Scientific Research Innovation Projects(KYLX16_0798)the Priority Academic Program Development of Jiangsu Higher Education InstitutionsProduction,Education&Research Cooperative Innovation Fund Project of Jiangsu Province(BY2015057-23)
文摘The present paper reported the structural and luminescent properties of Eu^（2＋） and Nd^（3＋） doped CaAl_2O_4 phosphor. The samples were prepared by microwave-assisted chemical co-precipitation（MA-CCP）, a synthesis technique which is suitable for small and uniform particle that could be used directly without grinding. The effects of different microwave temperatures on structure and photoluminescence behavior were studied. Formation of a phosphor and phase purity were confirmed by X-ray diffraction technique（XRD） with variable microwave temperatures. XRD analysis showed that the phosphors prepared by MA-CCP method at the temperature of 750, 900oC, respectively and solid-state reaction（SSR） method at 1300oC consisted of impurities. Commission Internationale de L＇Eclairage（CIE） color coordinates of CaAl_2O_4：Eu^（2＋）,Nd^（3＋） were suitable as blue light emitting phosphor. Excitation and emission peaks of the samples prepared by different methods in this study were almost the same. The images of SEM showed that the size of the phosphors prepared by MA-CCP method reached a submicrometer.
