In the highest-power chirped-pulse amplification lasers, the pulse must be stretched in time, amplified, compressed in a grating compressor and subsequently focused by off-axis parabola to obtain a high peak power. In...In the highest-power chirped-pulse amplification lasers, the pulse must be stretched in time, amplified, compressed in a grating compressor and subsequently focused by off-axis parabola to obtain a high peak power. In the optical terminal, the temporal and spatial effects of mismatched multigrating tiled compressor on the far-field pulse are critical factors to be analysed. In this paper, a k-space raytracing model is proposed for the temporal and spatial analyses of possible errors in a four-grating single-pass tiled compressor. The results show that the last grating affects mainly the partial focal spot, while the middle two gratings affect the temporal waveform, and the partial focal spot needs much higher error control than that in the temporal domain in a picosecond pulse compression.展开更多
The Ethernet passive optical network(EPON) is the next generation of broad-band network technique.A crucial issue in EPONs is the sharing of uplink bandwidth among optical network units(ONUs).This article provides a n...The Ethernet passive optical network(EPON) is the next generation of broad-band network technique.A crucial issue in EPONs is the sharing of uplink bandwidth among optical network units(ONUs).This article provides a novel dynamic bandwidth allocation algorithm,i.e.threshold dynamic bandwidth allocation(TDBA),which is based on adaptive threshold,to increase resource utilization.The algorithm uses ONU data-transmitting rate to adjust optical line terminal(OLT) receiving data threshold from an ONU.Simulation results show that this algorithm can decrease average packet delay and increase network throughput in a 10G EPON system.展开更多
The optical properties of F- and H-terminated silicon nanoribbons with armchair edges(F- and H- terminated ASi NRs)are compared by using the first-principles within the density function theory(DFT) framework. The ...The optical properties of F- and H-terminated silicon nanoribbons with armchair edges(F- and H- terminated ASi NRs)are compared by using the first-principles within the density function theory(DFT) framework. The results show that compared with for H-terminated 7-ASi NR, the dielectric function for the F-terminated 7-ASi NR has a red shift, which is mainly attributed to the narrower band gap because of the σ–π mixing effect of F–Si bonds in F-terminated 7-ASi NR.The peaks in the energy loss spectra for both systems represent the characteristics associated with the plasma resonance,which correspond to the trailing edges in the reflection spectra. These properties show that the different terminated atoms in7-ASi NRs affect mainly the optical properties in the low energy range. Because of the rich optical properties, the 7-ASi NR could be a potential candidate for photoelectric nanodevice.展开更多
Optically active and inactive hyperbranched polymers with specific thermoresponsive behaviours in water were reported.Through two steps hyperbranched polyethylenimine(HPEI) polymers terminated with different amount ...Optically active and inactive hyperbranched polymers with specific thermoresponsive behaviours in water were reported.Through two steps hyperbranched polyethylenimine(HPEI) polymers terminated with different amount of D-phenylalanine(D-Phe),L-phenylalanine(L-Phe) or DL-phenylalanine(DL-Phe) were prepared and characterized.The analyses on the solution properties by turbidimetry,dynamic light scattering,fluorescence probe and 1H-NMR demonstrated that all the polymers exhibited specific thermoresponsive behaviours in water,including:(1) In the dilute polymer concentration region,increasing the polymer concentration led to the increase of phase transition temperature;(2) The optically inactive thermoresponsive hyperbranched polymers showed a higher cloud-point temperature(Tcp) than their corresponding optically active ones in a relatively higher polymer concentration;(3) At the same polymer concentration the hydrophobic groups of the optically inactive HPEI-DL-Phe formed more perfect hydrophobic domain than those of the optically active HPEI-L-Phe and HPEI-D-Phe.展开更多
基金Project supported by the National High Technology Research and Development Program of China(Grant No.2009AA8044005)
文摘In the highest-power chirped-pulse amplification lasers, the pulse must be stretched in time, amplified, compressed in a grating compressor and subsequently focused by off-axis parabola to obtain a high peak power. In the optical terminal, the temporal and spatial effects of mismatched multigrating tiled compressor on the far-field pulse are critical factors to be analysed. In this paper, a k-space raytracing model is proposed for the temporal and spatial analyses of possible errors in a four-grating single-pass tiled compressor. The results show that the last grating affects mainly the partial focal spot, while the middle two gratings affect the temporal waveform, and the partial focal spot needs much higher error control than that in the temporal domain in a picosecond pulse compression.
文摘The Ethernet passive optical network(EPON) is the next generation of broad-band network technique.A crucial issue in EPONs is the sharing of uplink bandwidth among optical network units(ONUs).This article provides a novel dynamic bandwidth allocation algorithm,i.e.threshold dynamic bandwidth allocation(TDBA),which is based on adaptive threshold,to increase resource utilization.The algorithm uses ONU data-transmitting rate to adjust optical line terminal(OLT) receiving data threshold from an ONU.Simulation results show that this algorithm can decrease average packet delay and increase network throughput in a 10G EPON system.
基金Project supported by the Henan Provincial Joint Funds of the National Natural Science Foundation of China(Grant Nos.U1404608 and U1304612)the Science and Technology Key Projects of Henan Province+2 种基金China(Grant No.1502102210124)the Special Fund for Theoretical Science Foundation of Nanyang Normal UniversityChina(Grant No.ZX2013018)
文摘The optical properties of F- and H-terminated silicon nanoribbons with armchair edges(F- and H- terminated ASi NRs)are compared by using the first-principles within the density function theory(DFT) framework. The results show that compared with for H-terminated 7-ASi NR, the dielectric function for the F-terminated 7-ASi NR has a red shift, which is mainly attributed to the narrower band gap because of the σ–π mixing effect of F–Si bonds in F-terminated 7-ASi NR.The peaks in the energy loss spectra for both systems represent the characteristics associated with the plasma resonance,which correspond to the trailing edges in the reflection spectra. These properties show that the different terminated atoms in7-ASi NRs affect mainly the optical properties in the low energy range. Because of the rich optical properties, the 7-ASi NR could be a potential candidate for photoelectric nanodevice.
基金financially supported by the National Natural Science Foundation of China(Nos.20804027 and 21274106)Shanghai Key Laboratory of Magnetic Resonance
文摘Optically active and inactive hyperbranched polymers with specific thermoresponsive behaviours in water were reported.Through two steps hyperbranched polyethylenimine(HPEI) polymers terminated with different amount of D-phenylalanine(D-Phe),L-phenylalanine(L-Phe) or DL-phenylalanine(DL-Phe) were prepared and characterized.The analyses on the solution properties by turbidimetry,dynamic light scattering,fluorescence probe and 1H-NMR demonstrated that all the polymers exhibited specific thermoresponsive behaviours in water,including:(1) In the dilute polymer concentration region,increasing the polymer concentration led to the increase of phase transition temperature;(2) The optically inactive thermoresponsive hyperbranched polymers showed a higher cloud-point temperature(Tcp) than their corresponding optically active ones in a relatively higher polymer concentration;(3) At the same polymer concentration the hydrophobic groups of the optically inactive HPEI-DL-Phe formed more perfect hydrophobic domain than those of the optically active HPEI-L-Phe and HPEI-D-Phe.