The cascaded chirp fiber Bragg gratings(CFBGs) with ITU-T standard wavelengths and wavelength grid are applied to compensate the dispersion of 8×10 Gb/s WDM system.The ASE of the EDFA could be reduced,the OSNR of...The cascaded chirp fiber Bragg gratings(CFBGs) with ITU-T standard wavelengths and wavelength grid are applied to compensate the dispersion of 8×10 Gb/s WDM system.The ASE of the EDFA could be reduced,the OSNR of the transmitted signal can be increased and the fluctuation of the EDFA gain can be restrained in a certain scope by the CFBG employed in the system.Experiment of error-free 8×10 Gb/s 2 015 km transmission without FEC and electric regeneration is demonstrated in this paper.In this system,only EDFA is used as amplifier,and no other form of dispersion compensator is adopted except CFBG.The experimental result showed that after 2015 km transmission,the consistency of the dispersion compensating for each channel is perfect.展开更多
This paper introduces an ant colony routing and wavelength assignment algorithm based on cross-layer design(CL-ACRWA),which can overcome the adverse effects of Doppler wavelength shift on data transmission in optical ...This paper introduces an ant colony routing and wavelength assignment algorithm based on cross-layer design(CL-ACRWA),which can overcome the adverse effects of Doppler wavelength shift on data transmission in optical satellite networks. Firstly, a cross-layer optimization model is built, which considers the Doppler wavelength shift, the transmission delay as well as wavelength-continuity constraint. Then an ant colony algorithm is utilized to solve the cross-layer optimization model, resulting in finding an optimal light path satisfying the above constraints for every connection request. The performance of CL-ACRWA is measured by the communication success probability, the convergence property and the transmission delay. Simulation results show that CL-ACRWA performs well in communication success probability and has good global search ability as well as fast convergence speed. Meanwhile, the transmission delay can meet the basic requirement of real-time transmission of business.展开更多
The time-resolved photoluminescence and steady photoluminescence (TRPL and PL) spectra on self-assembled InAs/GaAs quantum dots (QDs) are investigated. By depositing GaAs/InAs short period superlattices (SLs), 1.48μm...The time-resolved photoluminescence and steady photoluminescence (TRPL and PL) spectra on self-assembled InAs/GaAs quantum dots (QDs) are investigated. By depositing GaAs/InAs short period superlattices (SLs), 1.48μm emission is obtained at room temperature. Temperature dependent PL measurements show that the PL intensity of the emission is very steady. It decays only to half as the temperature increases from 15K to room temperature, while at the same time, the intensity of the other emission decreases by a factor of 5 orders of magnitude. These two emissions are attributed to large-size QDs and short period superlattices (SLs), respectively. Large-size QDs are easier to capture and confine carriers, which benefits the lifetime of PL, and therefore makes the emission intensity insensitive to the temperature.展开更多
Defining abnormal transmittance as the case where the magnitude of the shortwave flux transmittance is greater than 1.0,the authors used surface solar irradiance and all-sky images obtained at the Yangbajing site in T...Defining abnormal transmittance as the case where the magnitude of the shortwave flux transmittance is greater than 1.0,the authors used surface solar irradiance and all-sky images obtained at the Yangbajing site in Tibet to analyze the reasons for the occurrence of abnormal shortwave flux transmittance.Based on the International Intercomparision of Three-Dimensional Radiation Code(I3RC) Monte Carlo community model of three-dimensional radiative transfer,the authors also performed simulations at a nonabsorbing wavelength and an absorbing wavelength through a stratocumulus and a cumulus field.The results showed the detection of abnormal transmittance on more than half the days,and the maximum transmittance was 1.34.The probability of the occurrence of abnormal transmittance appeared to be largest in summer,and on a daily basis was mainly at about noon local time.Abnormal transmittance mainly appeared when clear sky and clouds co-existed,especially at the edges of broken clouds and nearby regions with clear-sky conditions.The flux transmittance decreased as the solar zenith angle increased.展开更多
文摘The cascaded chirp fiber Bragg gratings(CFBGs) with ITU-T standard wavelengths and wavelength grid are applied to compensate the dispersion of 8×10 Gb/s WDM system.The ASE of the EDFA could be reduced,the OSNR of the transmitted signal can be increased and the fluctuation of the EDFA gain can be restrained in a certain scope by the CFBG employed in the system.Experiment of error-free 8×10 Gb/s 2 015 km transmission without FEC and electric regeneration is demonstrated in this paper.In this system,only EDFA is used as amplifier,and no other form of dispersion compensator is adopted except CFBG.The experimental result showed that after 2015 km transmission,the consistency of the dispersion compensating for each channel is perfect.
基金supported by the National Natural Science Foundation of China(No.61675033,61575026,61675233)National High Technical Research and Development Program of China(No.2015AA015504)
文摘This paper introduces an ant colony routing and wavelength assignment algorithm based on cross-layer design(CL-ACRWA),which can overcome the adverse effects of Doppler wavelength shift on data transmission in optical satellite networks. Firstly, a cross-layer optimization model is built, which considers the Doppler wavelength shift, the transmission delay as well as wavelength-continuity constraint. Then an ant colony algorithm is utilized to solve the cross-layer optimization model, resulting in finding an optimal light path satisfying the above constraints for every connection request. The performance of CL-ACRWA is measured by the communication success probability, the convergence property and the transmission delay. Simulation results show that CL-ACRWA performs well in communication success probability and has good global search ability as well as fast convergence speed. Meanwhile, the transmission delay can meet the basic requirement of real-time transmission of business.
基金Natural Science Foundation of Fujian Province(A992001)
文摘The time-resolved photoluminescence and steady photoluminescence (TRPL and PL) spectra on self-assembled InAs/GaAs quantum dots (QDs) are investigated. By depositing GaAs/InAs short period superlattices (SLs), 1.48μm emission is obtained at room temperature. Temperature dependent PL measurements show that the PL intensity of the emission is very steady. It decays only to half as the temperature increases from 15K to room temperature, while at the same time, the intensity of the other emission decreases by a factor of 5 orders of magnitude. These two emissions are attributed to large-size QDs and short period superlattices (SLs), respectively. Large-size QDs are easier to capture and confine carriers, which benefits the lifetime of PL, and therefore makes the emission intensity insensitive to the temperature.
基金supported by the National Natural Science Foundation of China (Grant No.41275040)
文摘Defining abnormal transmittance as the case where the magnitude of the shortwave flux transmittance is greater than 1.0,the authors used surface solar irradiance and all-sky images obtained at the Yangbajing site in Tibet to analyze the reasons for the occurrence of abnormal shortwave flux transmittance.Based on the International Intercomparision of Three-Dimensional Radiation Code(I3RC) Monte Carlo community model of three-dimensional radiative transfer,the authors also performed simulations at a nonabsorbing wavelength and an absorbing wavelength through a stratocumulus and a cumulus field.The results showed the detection of abnormal transmittance on more than half the days,and the maximum transmittance was 1.34.The probability of the occurrence of abnormal transmittance appeared to be largest in summer,and on a daily basis was mainly at about noon local time.Abnormal transmittance mainly appeared when clear sky and clouds co-existed,especially at the edges of broken clouds and nearby regions with clear-sky conditions.The flux transmittance decreased as the solar zenith angle increased.
