Performance metrics and design considerations for a free-space optical orbital-angular-momentum-multiplexed communication link
Performance metrics and design considerations for a free-space optical orbital-angular-momentum-multiplexed communication link
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DOI：
10.1364/optica.2.000357
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发表时间：
2015-04-20
期刊：
影响因子：
10.4
通讯作者：
Willner, Alan E.
中科院分区：
文献类型：
--
作者：
Xie, Guodong;Li, Long;Willner, Alan E.
多个轨道角动量（OAM）光束的同时传输有可能提高自由空间光通信链路的容量。对于这样的OAM复用方法，需要收集足够的功率以及用于具有最小串扰的系统的相位波前的比例。在这里，我们研究的OAM复用的自由空间数据链路的设计考虑因素，分析功率损耗，信道串扰，和功率损失的链路的情况下，有限大小的接收器孔径和发射器和接收器之间的未对准。我们描述了在给定的横向位移或接收器角度误差下，不同的发射光束尺寸、接收器孔径尺寸和发射OAM光束的模式间隔的权衡。通过仿真和实验，我们发现：（1）发射光束尺寸和接收孔径越大，系统对横向位移的容忍度越高，但对接收角度误差的容忍度越低;（2）模式间距越大，使用的OAM电荷越多，系统的功率损耗越大，但信道串扰越小;因此当系统功率损耗占主导时，具有小模式间隔的系统显示出较低的系统功率损失（例如，小的横向位移或接收器角度误差），而具有较大模式间隔的模式在信道串扰占主导时显示出较低的功率损失（例如，较大的横向位移或接收器角度误差）。该工作对OAM复用FSO链路的实际实现具有一定的参考价值。(C)2015美国光学学会
The capacity of free-space optical (FSO) communication links could potentially be increased by the simultaneous transmission of multiple orbital angular momentum (OAM) beams. For such an OAM multiplexing approach, one requires the collection of adequate power as well as proportion of the phase front for a system with minimal crosstalk. Here we study the design considerations for an OAM-multiplexed free-space data link, analyzing the power loss, channel crosstalk, and power penalty of the link in the case of limited-size receiver apertures and misalignment between the transmitter and the receiver. We describe the trade-offs for different transmitted beam sizes, receiver aperture sizes, and mode spacing of the transmitted OAM beams under given lateral displacements or receiver angular errors. Through simulations and some experiments, we show that (1) a system with a larger transmitted beam size and a larger receiver aperture is more tolerant to lateral displacement but less tolerant to the receiver angular error, and (2) a system with a larger mode spacing, which uses larger OAM charges, suffers more system power loss but less channel crosstalk; thus, a system with a small mode spacing shows a lower system power penalty when system power loss dominates (e.g., a small lateral displacement or receiver angular error), whereas that with a larger mode spacing shows a lower power penalty when channel crosstalk dominates (e.g., a larger lateral displacement or receiver angular error). This work could be beneficial to the practical implementation of OAM-multiplexed FSO links. (C) 2015 Optical Society of America