The superposition of basic non-diffracting beams triggered new research hotspots lately,laying opportunities for long-distance wireless optical communication.The Lommel-Gaussian(LMG)beam formed by the superposition of...The superposition of basic non-diffracting beams triggered new research hotspots lately,laying opportunities for long-distance wireless optical communication.The Lommel-Gaussian(LMG)beam formed by the superposition of Bessel-Gaussian light not only possesses non-diffraction feature,but also has tunable symmetry.With the help of Poynting vector analysis,we observed a smaller radial energy flow component during the propagation of the high order symmetrical LMG beam,which allows it to maintain the original beam profile over long distance.Thanks to the energy oscillation of the mainlobe and sidelobes,the mainlobe blocked by the symmetrical LMG beam can be restored.Also,the random phase screen with angular spectrum method is used to describe the beam behaviors in turbulence.The results show that the symmetry LMG is preferred in free space optical communication,and the asymmetric LMG performs poorly due to asymmetric energy transfer.展开更多
Laser communication is essential part of maritime-terrestrial-air intelligent communication/sensor network. Among them, different modulation formats would play a unique role in specific applications. Based on Rytov th...Laser communication is essential part of maritime-terrestrial-air intelligent communication/sensor network. Among them, different modulation formats would play a unique role in specific applications. Based on Rytov theory, we discussed system performance of the maritime laser communication with repeated coding technology in several modulation schemes. The closed-form expression of average bit error rate(BER) from weak to moderate atmospheric turbulence described by log-normal distribution is given. Differential phase shift keying(DPSK) modulation, as a potential solution for future maritime laser communication, has attracted a lot of attention. We analyzed the effects of atmospheric turbulence parameters(visibility, refractive index structure coefficient, non-Kolmogorov spectral power-law exponent, turbulence inner scale) and DPSK system parameters(receiver aperture diameter, repeat time) on average BER in detail. Compared with the aperture-averaging effects, the system BER can be well suppressed through increasing repeat time. This work is anticipated to provide a theoretical reference for maritime laser communication systems.展开更多
与传统的射频链路相比,自由空间光通信FSOC(Free Space Optical Communication)系统是对现有无线通信技术的有力补充,为了抑制大气湍流对信号光束带来的相位噪声和强度波动,有必要对通信信道状况进行实时监测。首先介绍了基于光斑质心...与传统的射频链路相比,自由空间光通信FSOC(Free Space Optical Communication)系统是对现有无线通信技术的有力补充,为了抑制大气湍流对信号光束带来的相位噪声和强度波动,有必要对通信信道状况进行实时监测。首先介绍了基于光斑质心漂移的大气折射率结构常数测量方法,利用大口径接收靶面和窄带滤光片,结合实时图像处理算法,实现了大气折射率结构常数的全天候实时监测。将大气折射率结构常数和光强闪烁指数进行了比较分析,测量结果表明它们的包络之间具有很好的线性关系,进一步验证了实时测量系统的可靠性。展开更多
基金supported by the National Key R&D Program of China(No.2018YFB1802302)the National Natural Science Foundation of China(Nos.11774181,61727815,11274182,11904180,11804250 and 1190426)+2 种基金the Natural Science Foundation of Tianjin(Nos.19JCYBJC16700 and 20JCQNJC01480)the Science and Technology Project of Tianjin(No.20YDTPJC00760)the Tianjin Development Program for Innovation and Entrepreneurship。
文摘The superposition of basic non-diffracting beams triggered new research hotspots lately,laying opportunities for long-distance wireless optical communication.The Lommel-Gaussian(LMG)beam formed by the superposition of Bessel-Gaussian light not only possesses non-diffraction feature,but also has tunable symmetry.With the help of Poynting vector analysis,we observed a smaller radial energy flow component during the propagation of the high order symmetrical LMG beam,which allows it to maintain the original beam profile over long distance.Thanks to the energy oscillation of the mainlobe and sidelobes,the mainlobe blocked by the symmetrical LMG beam can be restored.Also,the random phase screen with angular spectrum method is used to describe the beam behaviors in turbulence.The results show that the symmetry LMG is preferred in free space optical communication,and the asymmetric LMG performs poorly due to asymmetric energy transfer.
基金This work has been supported by the National Key R&D Program of China(No.2018YFB1802302)the National Natural Science Foundation of China(Nos.11774181,61727815,11274182,11904180,11804250 and 1190426)+2 种基金the Science and Technology Support Project of Tianjin(No.16YFZCSF00400)the Natural Science Foundation of Tianjin(No.19JCYBJC16700)the Tianjin Development Program for Innovation and Entrepreneurship。
文摘Laser communication is essential part of maritime-terrestrial-air intelligent communication/sensor network. Among them, different modulation formats would play a unique role in specific applications. Based on Rytov theory, we discussed system performance of the maritime laser communication with repeated coding technology in several modulation schemes. The closed-form expression of average bit error rate(BER) from weak to moderate atmospheric turbulence described by log-normal distribution is given. Differential phase shift keying(DPSK) modulation, as a potential solution for future maritime laser communication, has attracted a lot of attention. We analyzed the effects of atmospheric turbulence parameters(visibility, refractive index structure coefficient, non-Kolmogorov spectral power-law exponent, turbulence inner scale) and DPSK system parameters(receiver aperture diameter, repeat time) on average BER in detail. Compared with the aperture-averaging effects, the system BER can be well suppressed through increasing repeat time. This work is anticipated to provide a theoretical reference for maritime laser communication systems.
文摘与传统的射频链路相比,自由空间光通信FSOC(Free Space Optical Communication)系统是对现有无线通信技术的有力补充,为了抑制大气湍流对信号光束带来的相位噪声和强度波动,有必要对通信信道状况进行实时监测。首先介绍了基于光斑质心漂移的大气折射率结构常数测量方法,利用大口径接收靶面和窄带滤光片,结合实时图像处理算法,实现了大气折射率结构常数的全天候实时监测。将大气折射率结构常数和光强闪烁指数进行了比较分析,测量结果表明它们的包络之间具有很好的线性关系,进一步验证了实时测量系统的可靠性。
