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Terabit free-space data transmission employing orbital angular momentum multiplexing


The recognition in the 1990s that light beams with a helical phase front have orbital angular momentum has benefited applications ranging from optical manipulation to quantum information processing. Recently, attention has been directed towards the opportunities for harnessing such beams in communications. Here, we demonstrate that four light beams with different values of orbital angular momentum and encoded with 42.8 × 4 Gbit s−1 quadrature amplitude modulation (16-QAM) signals can be multiplexed and demultiplexed, allowing a 1.37 Tbit s−1 aggregated rate and 25.6 bit s−1 Hz−1 spectral efficiency when combined with polarization multiplexing. Moreover, we show scalability in the spatial domain using two groups of concentric rings of eight polarization-multiplexed 20 × 4 Gbit s−1 16-QAM-carrying orbital angular momentum beams, achieving a capacity of 2.56 Tbit s−1 and spectral efficiency of 95.7 bit s−1 Hz−1. We also report data exchange between orbital angular momentum beams encoded with 100 Gbit s−1 differential quadrature phase-shift keying signals. These demonstrations suggest that orbital angular momentum could be a useful degree of freedom for increasing the capacity of free-space communications.

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Figure 1: Concept and principle.
Figure 2: Block diagram of the experimental set-up.
Figure 3: Experimental and theoretical results of multiplexing/demultiplexing of four OAM beams.
Figure 4: Experimental results of 16-QAM signals over pol-muxed OAM beams.
Figure 5: Data exchange between OAM beams.
Figure 6: Data exchange between 100 Gbit s−1 RZ-DQPSK-carrying OAM beams.

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The authors thank A. Bozovich, B. Shamee, L. Zhang, K. Birnbaum, J. Choi, B. Erkmen, M. Neifeld and R. Willis for very fruitful discussions. This work was supported by the Defense Advanced Research Projects Agency (DARPA) under the InPho (Information in a Photon) programme.

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Authors and Affiliations



J.W., J.Y.Y., I.M.F., H.H., Y.Y., S.D., M.T. and A.E.W. developed the concept and conceived the experiments. J.W. performed the theoretical and numerical analyses. J.W., J.Y.Y., I.M.F., N.A., Y.Y., H.H., Y.R. and Y.Y. carried out the measurements and analysed the data. S.D., M.T. and A.E.W. provided technical support. All authors contributed to writing and finalizing the Article.

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Correspondence to Jian Wang or Alan E. Willner.

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The authors declare no competing financial interests.

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Wang, J., Yang, JY., Fazal, I. et al. Terabit free-space data transmission employing orbital angular momentum multiplexing. Nature Photon 6, 488–496 (2012).

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