A magneto-optical trap (MOT) for cesium atoms that operates without a separate repumping laser is reported. The differences between a normal MOT and this kind of MOT have been experimentally studied. The influences of...A magneto-optical trap (MOT) for cesium atoms that operates without a separate repumping laser is reported. The differences between a normal MOT and this kind of MOT have been experimentally studied. The influences of a repumping laser on cooling and trapping cesium atoms in the MOT have been carefully investigated. The results reveal that it is the critical injection-locked state of the diode laser that makes magneto-optical trapping of cesium atoms possible without a separate repumping laser.展开更多
The Rabi oscillations in two-component Bose-Einstein condensates with a coupling drive are studiedby means of a pair of bosonic operators. The coupling drive and initial phase difference will affect the amplitudeand t...The Rabi oscillations in two-component Bose-Einstein condensates with a coupling drive are studiedby means of a pair of bosonic operators. The coupling drive and initial phase difference will affect the amplitudeand the period of the Rabi oscillations. The Rabi oscillations will vanish in the evolution of the condensate densityfor some special initial phase differences (ψ = 0 or π). Our theory provides not only an analytical framework forquantitative predictions for two-component condensates, but also gives an intuitive understanding of some mysteriousfeatures observed in experiments and numerical. simulations.展开更多
A reliable,efficient and electrically-pumped Si-based laser is considered as the main challenge to achieve the integration of all key building blocks with silicon photonics.Despite the impressive advances that have be...A reliable,efficient and electrically-pumped Si-based laser is considered as the main challenge to achieve the integration of all key building blocks with silicon photonics.Despite the impressive advances that have been made in developing 1.3-μm Si-based quantum dot(QD)lasers,extending the wavelength window to the widely used 1.55-μm telecommunication region remains difficult.In this study,we develop a novel photonic integration method of epitaxial growth of III-V on a wafer-scale InP-on-Si(100)(InPOS)heterogeneous substrate fabricated by the ion-cutting technique to realize integrated lasers on Si substrate.This ion-cutting plus epitaxial growth approach decouples the correlated root causes of many detrimental dislocations during heteroepitaxial growth,namely lattice and domain mismatches.Using this approach,we achieved state-of-the-art performance of the electrically-pumped,continuouswave(CW)1.55-μm Si-based laser with a room-temperature threshold current density of 0.65 kA/cm^(-2),and output power exceeding 155mW per facet without facet coating in CW mode.CW lasing at 120℃ and pulsed lasing at over 130℃ were achieved.This generic approach is also applied to other material systems to provide better performance and more functionalities for photonics and microelectronics.展开更多
The huge performance enhancements of the organometal halide perovskite solar cells(OHPSCs) have appealed enormous attention within recent ten years. Although the rapid growth of the device power conversion efficiency(...The huge performance enhancements of the organometal halide perovskite solar cells(OHPSCs) have appealed enormous attention within recent ten years. Although the rapid growth of the device power conversion efficiency(PCE) has attained over 25%, the contamination of health-hazardous components still holds back its sustainable applications. To reduce the lead usage, many groups have tried chemical lead reduction solutions: substituting the lead by other group 14 metal elements to realize the low-lead OHPSCs. Unfortunately, neither the PCE nor the stability, low-lead OHPSCs all lag far behind the state-ofthe-art conventional lead-based OHPSCs. In this work, we present a physical lead reduction(PLR) concept by reducing the perovskite film thickness to restrict the perovskite hazard risk with minor scarification in device performances. Through the simulation of transfer matrix model, we theoretically demonstrated that by introducing the optical space layer, the device PCE could maintain 96% of the original maximum value while attenuating the perovskite film thickness to one-third. This means that the usage of lead can be reduced by $70% with PLR concept, which could have broad appeal as a new lead reduction strategy towards high performance OHPSCs.展开更多
A pulse plasma chemical vapor deposition (CVD) technique was developed for improving the growth yield of single-walled carbon nanotubes (SWNTs) with a narrow chirality distribution. The growth yield of the SWNTs could...A pulse plasma chemical vapor deposition (CVD) technique was developed for improving the growth yield of single-walled carbon nanotubes (SWNTs) with a narrow chirality distribution. The growth yield of the SWNTs could be improved by repetitive short duration pulse plasma CVD, while maintaining the initial narrow chirality distribution. Detailed growth dynamics is discussed based on a systematic investigation by changing the pulse parameters. The growth of SWNTs with a narrow chirality distribution could be controlled by the difference in the nucleation time required using catalysts comprising relatively small or large particles as the key factor. The nucleation can be controlled by adjusting the pulse on/ofF time ratio and the total processing time.展开更多
基金the National Natural Science Foundation of China under Grant No.19704001the Doctoral Program Foundation of the Institute of Higher Education.
文摘A magneto-optical trap (MOT) for cesium atoms that operates without a separate repumping laser is reported. The differences between a normal MOT and this kind of MOT have been experimentally studied. The influences of a repumping laser on cooling and trapping cesium atoms in the MOT have been carefully investigated. The results reveal that it is the critical injection-locked state of the diode laser that makes magneto-optical trapping of cesium atoms possible without a separate repumping laser.
基金The project supported by National Natural Science Foundation of China under Grant Nos. 10174095 and 10175039, Science Fund under Grant No. 20001003, and Youth Foundation of Shanxi Province of China under Grant No. 20011002
文摘The Rabi oscillations in two-component Bose-Einstein condensates with a coupling drive are studiedby means of a pair of bosonic operators. The coupling drive and initial phase difference will affect the amplitudeand the period of the Rabi oscillations. The Rabi oscillations will vanish in the evolution of the condensate densityfor some special initial phase differences (ψ = 0 or π). Our theory provides not only an analytical framework forquantitative predictions for two-component condensates, but also gives an intuitive understanding of some mysteriousfeatures observed in experiments and numerical. simulations.
基金supported by the National Natural Science Foundation of China(62293521,62174167,12205119)Shanghai Rising-Star Program(22QA1410700)+2 种基金China Postdoctoral Science Foundation(2022M723282)Zhejiang Provincial Natural Science Foundation of China(LQ23F040002)Jiaxing Municipal Public Welfare Research Project(2022AY10027).
文摘A reliable,efficient and electrically-pumped Si-based laser is considered as the main challenge to achieve the integration of all key building blocks with silicon photonics.Despite the impressive advances that have been made in developing 1.3-μm Si-based quantum dot(QD)lasers,extending the wavelength window to the widely used 1.55-μm telecommunication region remains difficult.In this study,we develop a novel photonic integration method of epitaxial growth of III-V on a wafer-scale InP-on-Si(100)(InPOS)heterogeneous substrate fabricated by the ion-cutting technique to realize integrated lasers on Si substrate.This ion-cutting plus epitaxial growth approach decouples the correlated root causes of many detrimental dislocations during heteroepitaxial growth,namely lattice and domain mismatches.Using this approach,we achieved state-of-the-art performance of the electrically-pumped,continuouswave(CW)1.55-μm Si-based laser with a room-temperature threshold current density of 0.65 kA/cm^(-2),and output power exceeding 155mW per facet without facet coating in CW mode.CW lasing at 120℃ and pulsed lasing at over 130℃ were achieved.This generic approach is also applied to other material systems to provide better performance and more functionalities for photonics and microelectronics.
基金supported by the National Basic Research Program of China (2015CB932203)the National Natural Science Foundation of China (91733301, 61722501, 61377025, 91433203, and 61604121)Postdoctoral Innovative Talents Support Project (8206200013)
文摘The huge performance enhancements of the organometal halide perovskite solar cells(OHPSCs) have appealed enormous attention within recent ten years. Although the rapid growth of the device power conversion efficiency(PCE) has attained over 25%, the contamination of health-hazardous components still holds back its sustainable applications. To reduce the lead usage, many groups have tried chemical lead reduction solutions: substituting the lead by other group 14 metal elements to realize the low-lead OHPSCs. Unfortunately, neither the PCE nor the stability, low-lead OHPSCs all lag far behind the state-ofthe-art conventional lead-based OHPSCs. In this work, we present a physical lead reduction(PLR) concept by reducing the perovskite film thickness to restrict the perovskite hazard risk with minor scarification in device performances. Through the simulation of transfer matrix model, we theoretically demonstrated that by introducing the optical space layer, the device PCE could maintain 96% of the original maximum value while attenuating the perovskite film thickness to one-third. This means that the usage of lead can be reduced by $70% with PLR concept, which could have broad appeal as a new lead reduction strategy towards high performance OHPSCs.
文摘A pulse plasma chemical vapor deposition (CVD) technique was developed for improving the growth yield of single-walled carbon nanotubes (SWNTs) with a narrow chirality distribution. The growth yield of the SWNTs could be improved by repetitive short duration pulse plasma CVD, while maintaining the initial narrow chirality distribution. Detailed growth dynamics is discussed based on a systematic investigation by changing the pulse parameters. The growth of SWNTs with a narrow chirality distribution could be controlled by the difference in the nucleation time required using catalysts comprising relatively small or large particles as the key factor. The nucleation can be controlled by adjusting the pulse on/ofF time ratio and the total processing time.
