The increasing dependence on fossil fuels and the consequent CO_(2)emissions have prompted urgent energy and environmental challenges[1,2].Solar-driven CO_(2)conversion into value-added fuels offers a sustainable and ...The increasing dependence on fossil fuels and the consequent CO_(2)emissions have prompted urgent energy and environmental challenges[1,2].Solar-driven CO_(2)conversion into value-added fuels offers a sustainable and promising solution to these issues[3].However,the practical implementation of CO_(2)photoreduction is constrained by low efficiency,primarily due to the rapid recombination of photogenerated electron-hole pairs[4].展开更多
Tunnelling, acceleration, and collision of electrons are the basic events in the process of high harmonic generation(HHG) in strong-field interaction with atoms.However, the periodic array of atoms in semiconductor st...Tunnelling, acceleration, and collision of electrons are the basic events in the process of high harmonic generation(HHG) in strong-field interaction with atoms.However, the periodic array of atoms in semiconductor structure makes three steps become interatomic coherent process which leads to complicated carrier dynamics and two sources of high harmonic emission: interband polarization and intraband current.The difference of features of high harmonic generation between semiconductors and atoms is strongly linked to the unique presence of intraband motion which manifests itself a nontrivial role in intertwined two dynamics.Here, we review recent experimental and theoretical advances of understanding coupled interband and intraband mechanisms of HHG in semiconductors.Particularly we focus on the influence of intraband motion on the interband excitation, and on the subsequent HHG emission and attosecond pulse generation.展开更多
All optical network based on wavelength division multiplexing transmission system with optical cross connect (OXC) is an essential approach for optical commumications.Crosstalk introduced by OXC (specially large scale...All optical network based on wavelength division multiplexing transmission system with optical cross connect (OXC) is an essential approach for optical commumications.Crosstalk introduced by OXC (specially large scale one) is a key limiting factor for its capacity. Optical signal passing through a typical OXC is analyzed in this paper, followed by description of the generation and effect of intraband crosstalk.The power penalties induced by intraband crosstalk versus the number of multiplexed wavelengths M and the number of input fibers N have been given by numerical simulations. The results show that the coherent crosstalk is the most critical limitation on OXC and depends more closely on the number of multiplexed wavelengths M than the number of input fibers N . Crosstalk is suppressed by doubly filtering, fixing optimum decision-threshold and appropriately choosing the number of multiplexed wavelengths M .展开更多
针对在超长距10G光传输系统中,输出端光谱中发现明显的谱肩现象,并导致系统光信噪比限制的问题,本文分析提出其主要产生机制是由于入纤端10G小型可插拔(10 Gigabit Small Form Factor Pluggable,XFP)光调制模块所发出的调制信号与输入...针对在超长距10G光传输系统中,输出端光谱中发现明显的谱肩现象,并导致系统光信噪比限制的问题,本文分析提出其主要产生机制是由于入纤端10G小型可插拔(10 Gigabit Small Form Factor Pluggable,XFP)光调制模块所发出的调制信号与输入信号因满足相位匹配条件而导致带内简并四波混频现象的出现,进而在输出端与信号光谱合成成为明显谱肩。研究结果显示,随着入纤信号光传输功率的提高,谱肩现象愈加明显,并成为限制光传输功率大小的主导机制。本文基于四波混频理论通过数值仿真,将理论计算结果与实验数据拟合,深入分析了带内四波混频效应对光传输系统的限制因素,并进而提出了有效抑制此限制因素的三种方法。展开更多
The physical substance of the coherent control current and the optical rectification have been analyzed based on density matrix perturbation theory. The analytical results demonstrate that they arise from the real and...The physical substance of the coherent control current and the optical rectification have been analyzed based on density matrix perturbation theory. The analytical results demonstrate that they arise from the real and virtual manifestations of the same nonlinear process associated with diagonal and non-diagonal density matrix. And in terms of polarization, they respectively arise from the intraband and interband polarizations. Both the evolution of the coherent control current exited by ultrafast laser pulse and its dependence on frequency have been studied in time and frequency domains. In order to get an explicit knowledge of intraband polarization and the origination of the coherent control current, we have investigated the initial photo-carriers momentum distribution. The ultrafast decay of the polar momentum population in order of tens of femtosends is given to illustrate its instantaneous optical response.展开更多
文摘The increasing dependence on fossil fuels and the consequent CO_(2)emissions have prompted urgent energy and environmental challenges[1,2].Solar-driven CO_(2)conversion into value-added fuels offers a sustainable and promising solution to these issues[3].However,the practical implementation of CO_(2)photoreduction is constrained by low efficiency,primarily due to the rapid recombination of photogenerated electron-hole pairs[4].
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11674209 and 11774215)the High Level University Projects of Guangdong Province of China(Mathematics,Shantou University)+1 种基金the Open Fund of the State Key Laboratory of High Field Laser Physics(SIOM),Chinasupport of the Department of Education of Guangdong Province,China(Grant No.2018KCXTD011)
文摘Tunnelling, acceleration, and collision of electrons are the basic events in the process of high harmonic generation(HHG) in strong-field interaction with atoms.However, the periodic array of atoms in semiconductor structure makes three steps become interatomic coherent process which leads to complicated carrier dynamics and two sources of high harmonic emission: interband polarization and intraband current.The difference of features of high harmonic generation between semiconductors and atoms is strongly linked to the unique presence of intraband motion which manifests itself a nontrivial role in intertwined two dynamics.Here, we review recent experimental and theoretical advances of understanding coupled interband and intraband mechanisms of HHG in semiconductors.Particularly we focus on the influence of intraband motion on the interband excitation, and on the subsequent HHG emission and attosecond pulse generation.
文摘All optical network based on wavelength division multiplexing transmission system with optical cross connect (OXC) is an essential approach for optical commumications.Crosstalk introduced by OXC (specially large scale one) is a key limiting factor for its capacity. Optical signal passing through a typical OXC is analyzed in this paper, followed by description of the generation and effect of intraband crosstalk.The power penalties induced by intraband crosstalk versus the number of multiplexed wavelengths M and the number of input fibers N have been given by numerical simulations. The results show that the coherent crosstalk is the most critical limitation on OXC and depends more closely on the number of multiplexed wavelengths M than the number of input fibers N . Crosstalk is suppressed by doubly filtering, fixing optimum decision-threshold and appropriately choosing the number of multiplexed wavelengths M .
文摘针对在超长距10G光传输系统中,输出端光谱中发现明显的谱肩现象,并导致系统光信噪比限制的问题,本文分析提出其主要产生机制是由于入纤端10G小型可插拔(10 Gigabit Small Form Factor Pluggable,XFP)光调制模块所发出的调制信号与输入信号因满足相位匹配条件而导致带内简并四波混频现象的出现,进而在输出端与信号光谱合成成为明显谱肩。研究结果显示,随着入纤信号光传输功率的提高,谱肩现象愈加明显,并成为限制光传输功率大小的主导机制。本文基于四波混频理论通过数值仿真,将理论计算结果与实验数据拟合,深入分析了带内四波混频效应对光传输系统的限制因素,并进而提出了有效抑制此限制因素的三种方法。
文摘The physical substance of the coherent control current and the optical rectification have been analyzed based on density matrix perturbation theory. The analytical results demonstrate that they arise from the real and virtual manifestations of the same nonlinear process associated with diagonal and non-diagonal density matrix. And in terms of polarization, they respectively arise from the intraband and interband polarizations. Both the evolution of the coherent control current exited by ultrafast laser pulse and its dependence on frequency have been studied in time and frequency domains. In order to get an explicit knowledge of intraband polarization and the origination of the coherent control current, we have investigated the initial photo-carriers momentum distribution. The ultrafast decay of the polar momentum population in order of tens of femtosends is given to illustrate its instantaneous optical response.
