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Ali Shahpari Abdelgader Abdalla Ricardo Ferreira Giorgia Parca Jacklyn D. Reis Mario Lima 《Fiber and Integrated Optics》2014,33(3):149-162
AbstractThis article experimentally demonstrates a hybrid fiber–free-space passive optical network that enables high spectral density, aggregated capacity, and total throughput through ultra-dense wavelength-division multiplexing baseband and radio-over-fiber channels. Ultra-dense wavelength-division multiplexing 10-Gb/s Nyquist-shaped 16-ary quadrature amplitude modulation, 10-Gb/s radio-over-fiber orthogonal frequency-division multiplexing, and 8.75-Gb/s baseband orthogonal frequency-division multiplexing signals per user were transmitted through a maximum 40-km passive optical network, which includes a 6-m free-space optics link with acceptable performance. 相似文献
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Abstract In this article, various issues involved in a ground-to-satellite optical communication link (i.e., acquisition time, uncertainty area, and channel noise) are discussed. Acquisition time of a free-space optical link is evaluated for coherent (sub-carrier BPSK and QPSK) and non-coherent (OOK and -PPM) modulation schemes over weak turbulent channel with transmit diversity. In the analysis, both uncorrelated and correlated beams are considered. It is seen that an increase in transmit diversity order helps to improve the acquisition time, irrespective of turbulence strength in the atmosphere. At high correlation, a marginal change in acquisition time is observed with the increase in diversity order. 相似文献
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Optical crossbar switches were fabricated using multiwavelength vertical-cavity surface-emitting lasers and free-space microoptics. Four-channel optical switches with 10-nm wavelength intervals were successfully demonstrated. 相似文献
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A new method of calculating the orbital angular momentum spectra of Laguerre-Gaussian beams in channels with atmospheric turbulence 下载免费PDF全文
Studying orbital angular momentum(OAM) spectra is important for analyzing crosstalk in free-space optical(FSO)communication systems. This work offers a new method of simplifying the expressions for the OAM spectra of Laguerre-Gaussian(LG) beams under both weak/medium and strong atmospheric turbulences. We propose fixing the radius to the extreme point of the intensity distribution, review the expression for the OAM spectrum under weak/medium turbulence,derive the OAM spectrum expression for an LG beam under strong turbulence, and simplify both of them to concise forms.Then, we investigate the accuracy of the simplified expressions through simulations. We find that the simplified expressions permit accurate calculation of the OAM spectrum for large transmitted OAM numbers under any type of turbulence. Finally,we use the simplified expressions to analytically address the broadening of the OAM spectrum caused by atmospheric turbulence. This work should contribute to the concise theoretical derivation of analytical expressions for OAM channel matrices for FSO-OAM communications and the analytical study of the laws governing OAM spectra. 相似文献
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空间激光通信凭借其带宽优势,成为未来高速空间通信不可或缺的有效手段,是近年来国际上的研究热点。本文详细介绍了美国、欧洲和日本在空间激光通信技术领域的最新研究进展和未来发展规划,总结了国内外空间激光通信演示计划的主要参数指标。通过对空间激光通信最新研究计划的分析,归纳出空间激光通信高速化、深空化、集成化、网络化、一体化5个发展趋势,以及需要突破的高阶调制、高灵敏度探测、多制式兼容、"一对多"通信等关键技术。为我国激光通信设备及相关研究提供借鉴和参考。 相似文献
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为了设计最优光纤耦合系统,利用高斯模场近似单模阶跃光纤的模场和大模面积光子晶体光纤的模场,推导出了理想情况下空间激光与这两种光纤的耦合效率解析表达式以及光纤端面相对于耦合系统存在横向偏移和端面倾斜时的耦合效率解析表达式。基于上述理论表达式计算了空间激光与光纤的耦合效率,并通过实验验证了此理论表达式的有效性。理论计算和实验均证实了单模阶跃光纤对于横向偏移更敏感,当横向偏移量等于单模光纤的纤芯半径时所对应的耦合效率只有20.25%,为理论最大值的1/4;而大模面积光子晶体光纤对于端面倾斜更加敏感,当端面倾斜2°时对应的耦合效率只有40.5%,为理论最大值的1/2。所提出理论表达式和实验方法完全可以为设计光纤耦合系统提供准确的参数。 相似文献
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The concept of partially coherent nonparaxial modified Bessel--Gauss (MBG)
beams is proposed. Based on the generalized Rayleigh-Sommerfeld diffraction
integral, the analytical propagation equations of nonparaxial MBG beams in
free space are derived and analysed, and some special cases are discussed.
In particular, under the paraxial approximation our results reduce to the
corresponding paraxial ones. Numerical calculation examples are given to
illustrate the dependence of intensity and spectral degree of coherence on
the beam order $m$, \textit{$\xi $} and $f$ parameters, and to compare
the difference between the paraxial and nonparaxial results. 相似文献
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A unified hybrid free-space optical–radio-frequency (HFR) system based on photonic technology is proposed to simplify the system design and remove the restriction on the azimuth rotation for point-to-point wireless links between mobile platforms. The proposed system applies parallel channel coding techniques and photonic technology to unify the two channels. The principle of a photonic encoder for Alamouti codes is proposed and verified by simulations. A 10 Gbit/s data stream is correctly encoded with an acceptable waveform distortion. Photoelectronic integrated circuits for unified photonic codecs and transceivers could be developed based on this principle. 相似文献