The mode splitting induced by electro-optic birefringence in a P-I-N InGaAs/GaAs/A1GaAs vertical-cavity surface- emitting laser （VCSEL） has been studied by polarized electroluminescence （EL） at room temperature. T...The mode splitting induced by electro-optic birefringence in a P-I-N InGaAs/GaAs/A1GaAs vertical-cavity surface- emitting laser （VCSEL） has been studied by polarized electroluminescence （EL） at room temperature. The polarized EL spectra with E｜｜[110] and E ｜｜ [150] directions, are extracted for different injected currents. The mode splitting of the two orthogonal polarized modes for a VCSEL device is determined, and its value increases linearly with the increasing injected current due to electro-optic birefringence; This article demonstrates that the polarized EL is a powerful tool to study the mode splitting and polarization anisotropy of a VCSEL device.展开更多
Discrete choice model acts as one of the most important tools for studies involving mode split in the context of transport demand forecast. As different types of discrete choice models display their merits and restric...Discrete choice model acts as one of the most important tools for studies involving mode split in the context of transport demand forecast. As different types of discrete choice models display their merits and restrictions diversely, how to properly select the specific type among discrete choice models for realistic application still remains to be a tough problem. In this article, five typical discrete choice models for transport mode split are, respectively, discussed, which includes multinomial logit model, nested logit model （NL）, heteroscedastic extreme value model, multinominal probit model and mixed multinomial logit model （MMNL）. The theoretical basis and application attributes of these five models are especially analysed with great attention, and they are also applied to a realistic intercity case of mode split forecast, which results indi- cating that NL model does well in accommodating similarity and heterogeneity across alternatives, while MMNL model serves as the most effective method for mode choice prediction since it shows the highest reliability with the least significant prediction errors and even outperforms the other four models in solving the heterogeneity and similarity problems. This study indicates that conclusions derived from a single discrete choice model are not reliable, and it is better to choose the proper model based on its characteristics.展开更多
Optomechanical dynamics in two systems which are a transmission line resonator and Fabrya-Perot optical cavity via radiation-pressure are investigated by linearized quantum Langevin equation. We work in the resolved s...Optomechanical dynamics in two systems which are a transmission line resonator and Fabrya-Perot optical cavity via radiation-pressure are investigated by linearized quantum Langevin equation. We work in the resolved sideband regime where the oscillator resonance frequency exceeds the cavity linewidth. Normal mode splittings of the mechanical resonator as a pure result of the coupling interaction in the two optomechanical systems is studied, and we make a comparison of normal mode splitting of mechanical resonator between the two systems. In the optical cavity, the normal mode splitting of the movable mirror approaches the latest experiment very well. In addition, an approximation scheme is introduced to demonstrate the ground state cooling, and we make a comparison of cooling between the two systems dominated by two key factors, which are the initial bath temperature and the mechanical quality factor. Since both the normal mode splitting and cooling require working in the resolved sideband regime, whether the normal mode splitting influences the cooling of the mirror is considered. Considering the size of the mechanical resonator and precooling the system, the mechanical resonator in the transmission line resonator system is easier to achieve the ground state cooling than in optical cavity.展开更多
The graphene-based double-barrier waveguides induced by electric field have been investigated. The guided modes can only exist in the case of Klein tunneling, and the fundamental mode is absent. The guided modes in th...The graphene-based double-barrier waveguides induced by electric field have been investigated. The guided modes can only exist in the case of Klein tunneling, and the fundamental mode is absent. The guided modes in the single-barrier waveguide split into symmetric and antisymmetric modes with different incident angles in the double-barrier waveguide. The phase difference between electron states and hole states is also discussed. The phase difference for the two splitting modes is close to each other and increases with the order of guided modes. These phenomena can be helpful for the potential applications in graphene-based optoelectronic devices.展开更多
A novel enhancement-mode AlGaN/GaN high electron mobility transistor（HEMT） is proposed and studied.Specifically,several split floating gates（FGs） with negative charges are inserted to the conventional MIS structur...A novel enhancement-mode AlGaN/GaN high electron mobility transistor（HEMT） is proposed and studied.Specifically,several split floating gates（FGs） with negative charges are inserted to the conventional MIS structure.The simulation results revealed that the V_（th） decreases with the increase of polarization sheet charge density and the tunnel dielectric（between FGs and AlGaN） thickness,while it increases with the increase of FGs sheet charge density and blocking dielectric（between FGs and control gate） thickness.In the case of the same gate length,the V_（th） will left shift with decreasing FG length.More interestingly,the split FGs could significantly reduce the device failure probability in comparison with the single large area FG structure.展开更多
基金Project supported the National Key Basic Research and Development Program of China (Grant Nos.2012CB921304 and 2013CB632805)the National Natural Science Foundation of China (Grant Nos.60990313,61306120,and 6106003)the Foundation of Fuzhou University (Grant No.022498)
文摘The mode splitting induced by electro-optic birefringence in a P-I-N InGaAs/GaAs/A1GaAs vertical-cavity surface- emitting laser （VCSEL） has been studied by polarized electroluminescence （EL） at room temperature. The polarized EL spectra with E｜｜[110] and E ｜｜ [150] directions, are extracted for different injected currents. The mode splitting of the two orthogonal polarized modes for a VCSEL device is determined, and its value increases linearly with the increasing injected current due to electro-optic birefringence; This article demonstrates that the polarized EL is a powerful tool to study the mode splitting and polarization anisotropy of a VCSEL device.
基金supported by the Science&Technology pillar project(No.0556)of Guangzhou
文摘Discrete choice model acts as one of the most important tools for studies involving mode split in the context of transport demand forecast. As different types of discrete choice models display their merits and restrictions diversely, how to properly select the specific type among discrete choice models for realistic application still remains to be a tough problem. In this article, five typical discrete choice models for transport mode split are, respectively, discussed, which includes multinomial logit model, nested logit model （NL）, heteroscedastic extreme value model, multinominal probit model and mixed multinomial logit model （MMNL）. The theoretical basis and application attributes of these five models are especially analysed with great attention, and they are also applied to a realistic intercity case of mode split forecast, which results indi- cating that NL model does well in accommodating similarity and heterogeneity across alternatives, while MMNL model serves as the most effective method for mode choice prediction since it shows the highest reliability with the least significant prediction errors and even outperforms the other four models in solving the heterogeneity and similarity problems. This study indicates that conclusions derived from a single discrete choice model are not reliable, and it is better to choose the proper model based on its characteristics.
基金supported by the National Natural Science Foundation of China (Grant Nos. 10647132 and 11104113)the Scientific Research Fund of Hunan Provincial Education Department of China (Grant No. 10A100)
文摘Optomechanical dynamics in two systems which are a transmission line resonator and Fabrya-Perot optical cavity via radiation-pressure are investigated by linearized quantum Langevin equation. We work in the resolved sideband regime where the oscillator resonance frequency exceeds the cavity linewidth. Normal mode splittings of the mechanical resonator as a pure result of the coupling interaction in the two optomechanical systems is studied, and we make a comparison of normal mode splitting of mechanical resonator between the two systems. In the optical cavity, the normal mode splitting of the movable mirror approaches the latest experiment very well. In addition, an approximation scheme is introduced to demonstrate the ground state cooling, and we make a comparison of cooling between the two systems dominated by two key factors, which are the initial bath temperature and the mechanical quality factor. Since both the normal mode splitting and cooling require working in the resolved sideband regime, whether the normal mode splitting influences the cooling of the mirror is considered. Considering the size of the mechanical resonator and precooling the system, the mechanical resonator in the transmission line resonator system is easier to achieve the ground state cooling than in optical cavity.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11204170 and 61108010)the Shanghai Municipal Commission of Science and Technology,China(Grant No.16ZR1411600)
文摘The graphene-based double-barrier waveguides induced by electric field have been investigated. The guided modes can only exist in the case of Klein tunneling, and the fundamental mode is absent. The guided modes in the single-barrier waveguide split into symmetric and antisymmetric modes with different incident angles in the double-barrier waveguide. The phase difference between electron states and hole states is also discussed. The phase difference for the two splitting modes is close to each other and increases with the order of guided modes. These phenomena can be helpful for the potential applications in graphene-based optoelectronic devices.
基金Project supported by“Efficient and Energy-Saving GaN on Si Power Devices”Research Fund(Grant No.KQCX20140522151322946)the Research Fund of the Third Generation Semiconductor Key Laboratory of Shenzhen,China(Grant No.ZDSYS20140509142721434)+1 种基金the“Key Technology Research of GaN on Si Power Devices”Research Fund(Grant No.JSGG20140729145956266)the“Research of Low Cost Fabrication of GaN Power Devices and System Integration”Research Fund(Grant No.JCYJ201602261926390)
文摘A novel enhancement-mode AlGaN/GaN high electron mobility transistor（HEMT） is proposed and studied.Specifically,several split floating gates（FGs） with negative charges are inserted to the conventional MIS structure.The simulation results revealed that the V_（th） decreases with the increase of polarization sheet charge density and the tunnel dielectric（between FGs and AlGaN） thickness,while it increases with the increase of FGs sheet charge density and blocking dielectric（between FGs and control gate） thickness.In the case of the same gate length,the V_（th） will left shift with decreasing FG length.More interestingly,the split FGs could significantly reduce the device failure probability in comparison with the single large area FG structure.
