Performance metrics and design considerations for a free-space optical orbital-angular-momentum–multiplexed communication link
- 8 April 2015
- journal article
- Published by Optica Publishing Group in Optica
- Vol. 2 (4), 357-365
- https://doi.org/10.1364/optica.2.000357
Abstract
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.Keywords
Funding Information
- Air Force Office of Scientific Research (AFOSR) (FA9550–15–C–0024)
- Defense Advanced Research Projects Agency (DARPA)
- Intel Labs University Research Office
- National Science Foundation Major Research Instrumentation Program (NFS–MRI)
- NxGen Partners
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