随着网络业务流量的增长,通信业务对密集波分复用(DWDM)的性能要求越来越高。为了提高传输效率,传输频谱逐渐向C+L Band传输扩展,Super C Band传输应运而生,但目前与之对应的掺铒光纤放大器(EDFA)相关研究较少。针对这一问题,文章提出...随着网络业务流量的增长,通信业务对密集波分复用(DWDM)的性能要求越来越高。为了提高传输效率,传输频谱逐渐向C+L Band传输扩展,Super C Band传输应运而生,但目前与之对应的掺铒光纤放大器(EDFA)相关研究较少。针对这一问题,文章提出了一种针对Super C Band传输的EDFA结构,基于Giles模型,分析了EDFA在Super C Band的特性,利用多级泵浦机制,设计了一种可以在Super C Band范围内进行放大的EDFA。结果表明,在-9.3 dBm入光时,该EDFA可以实现26 dB的平坦增益,16.7 dBm的输出功率,此时噪声指数小于5 dB,Ripple小于0.1 dB。并且根据需要,在入光处于-15.0~-3.5 dBm范围内时,通过调节泵浦功率与可调衰减器,均能够实现7~26 dB的可调增益。该EDFA可应用于5G传输和数据中心之间光纤通信等场合。展开更多
The valence band offsets of the strained and longitudinally relaxed diamond/cubic boron-nitride (c-BN) (110) superlattice are investigated by the plane wave density functional theory approach and using the on-site...The valence band offsets of the strained and longitudinally relaxed diamond/cubic boron-nitride (c-BN) (110) superlattice are investigated by the plane wave density functional theory approach and using the on-site core electron as a reference energy level. For the strained diamond/c-BN superlattice, the valence band offset of around 1.50 eV is in good agreement with those using all the electrons methods. As for the longitudinally relaxed superlattice, the valence band offset of around 1.28 eV is smaller than that of the strained superlattice. The reason for this is mainly due to the split of the valence band maximum caused by the anisotropic strain.展开更多
The objective of this study is to improve the performance of semi-empirical radar backscatter models, which are mainly used in microwave remote sensing (Oh 1992, Oh 2004 and Dubois). The study is based on satellite an...The objective of this study is to improve the performance of semi-empirical radar backscatter models, which are mainly used in microwave remote sensing (Oh 1992, Oh 2004 and Dubois). The study is based on satellite and ground data collected on bare soil surfaces during the Multispectral Crop Monitoring experimental campaign of the CESBIO laboratory in 2010 over an agricultural region in southwestern France. The dataset covers a wide range of soil (viewing top soil moisture, surface roughness and texture) and satellite (at different frequencies: X-, C- and L-bands, and different incidence angles: 24.3° to 53.3°) configurations. The proposed methodology consists in identifying and correcting the residues of the models, depending on the surface properties (roughness, moisture, texture) and/or sensor characteristics (frequency, incidence angle). Finally, one model has been retained for each frequency domain. Results show that the enhancements of the models significantly increase the simulation performances. The coefficient of correlation increases of 23% in mean and the simulation errors (RMSE) are reduced to below 2 dB (at the X and C-bands) and to 1 dB at the L-band, compared to the initial models. At the X- and C-bands, the best performances of the modified models are provided by Dubois, whereas Oh 2004 is more suitable for the L-band (r is equal to 0.69, 0.65 and 0.85). Moreover, the modified models of Oh 1992 and 2004 and Dubois, developed in this study, offer a wider domain of validity than the initial formalism and increase the capabilities of retrieving the backscattering signal in view of applications of such approaches to stronglycontrasted agricultural surface states.展开更多
文摘随着网络业务流量的增长,通信业务对密集波分复用(DWDM)的性能要求越来越高。为了提高传输效率,传输频谱逐渐向C+L Band传输扩展,Super C Band传输应运而生,但目前与之对应的掺铒光纤放大器(EDFA)相关研究较少。针对这一问题,文章提出了一种针对Super C Band传输的EDFA结构,基于Giles模型,分析了EDFA在Super C Band的特性,利用多级泵浦机制,设计了一种可以在Super C Band范围内进行放大的EDFA。结果表明,在-9.3 dBm入光时,该EDFA可以实现26 dB的平坦增益,16.7 dBm的输出功率,此时噪声指数小于5 dB,Ripple小于0.1 dB。并且根据需要,在入光处于-15.0~-3.5 dBm范围内时,通过调节泵浦功率与可调衰减器,均能够实现7~26 dB的可调增益。该EDFA可应用于5G传输和数据中心之间光纤通信等场合。
基金supported by the National Natural Science Foundation of China (Grant No.60877017)the Innovation Program of Shanghai Municipal Education Commission (Grant No.08YZ04)the Shanghai Leading Academic Discipline Project (Grant No.S30107)
文摘The valence band offsets of the strained and longitudinally relaxed diamond/cubic boron-nitride (c-BN) (110) superlattice are investigated by the plane wave density functional theory approach and using the on-site core electron as a reference energy level. For the strained diamond/c-BN superlattice, the valence band offset of around 1.50 eV is in good agreement with those using all the electrons methods. As for the longitudinally relaxed superlattice, the valence band offset of around 1.28 eV is smaller than that of the strained superlattice. The reason for this is mainly due to the split of the valence band maximum caused by the anisotropic strain.
文摘The objective of this study is to improve the performance of semi-empirical radar backscatter models, which are mainly used in microwave remote sensing (Oh 1992, Oh 2004 and Dubois). The study is based on satellite and ground data collected on bare soil surfaces during the Multispectral Crop Monitoring experimental campaign of the CESBIO laboratory in 2010 over an agricultural region in southwestern France. The dataset covers a wide range of soil (viewing top soil moisture, surface roughness and texture) and satellite (at different frequencies: X-, C- and L-bands, and different incidence angles: 24.3° to 53.3°) configurations. The proposed methodology consists in identifying and correcting the residues of the models, depending on the surface properties (roughness, moisture, texture) and/or sensor characteristics (frequency, incidence angle). Finally, one model has been retained for each frequency domain. Results show that the enhancements of the models significantly increase the simulation performances. The coefficient of correlation increases of 23% in mean and the simulation errors (RMSE) are reduced to below 2 dB (at the X and C-bands) and to 1 dB at the L-band, compared to the initial models. At the X- and C-bands, the best performances of the modified models are provided by Dubois, whereas Oh 2004 is more suitable for the L-band (r is equal to 0.69, 0.65 and 0.85). Moreover, the modified models of Oh 1992 and 2004 and Dubois, developed in this study, offer a wider domain of validity than the initial formalism and increase the capabilities of retrieving the backscattering signal in view of applications of such approaches to stronglycontrasted agricultural surface states.