January 2016
Spotlight Summary by Enrique J. Galvez
Experimental demonstration of 20 Gbit/s data encoding and 2 ns channel hopping using orbital angular momentum modes
Optical spatial modes were used as carriers for the repeated switching of communication channels, the optical-mode counterpart of frequency hopping in spread-spectrum radio communications. Instead of frequency hopping information to avoid jamming or eavesdropping in communications, the researchers used spatial modes as the carriers of optical information, to transmit time-multiplexed data streams in free space. Spatial modes have high potential for communications due to their high dimensionality and orthogonality. They can be used as a means to encode the information into high-dimensional alphabets, or as in this report, as distinct carriers that can be used for channel hopping, as is done in spread-spectrum communications, which is more immune to errors or interception and jamming. This has been demonstrated in the report by using information encoded in 100 Gbit/s quadrature-phase-shift-keyed data multiplexed into four spatial-mode channels. The authors investigated using several mode sets carrying orbital angular momentum with different topological charge difference. The modes were encoded and decoded in separate space channels, were time-multiplexed in and out of a single free-space communications channel. The authors analyze the feasibility of the scheme by diagnosing cross-talk and error rates.
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Article Information
Experimental demonstration of 20 Gbit/s data encoding and 2 ns channel hopping using orbital angular momentum modes
Asher J. Willner, Yongxiong Ren, Guodong Xie, Zhe Zhao, Yinwen Cao, Long Li, Nisar Ahmed, Zhe Wang, Yan Yan, Peicheng Liao, Cong Liu, Mohammad Mirhosseini, Robert W. Boyd, Moshe Tur, and Alan E. Willner
Opt. Lett. 40(24) 5810-5813 (2015) View: Abstract | HTML | PDF