Spatially multiplexed orbital-angular-momentum-encoded single photon and classical channels in a free-space optical communication link

Yongxiong Ren*, Cong Liu, Kai Pang, Jiapeng Zhao, Yinwen Cao, Guodong Xie, Long Li, Peicheng Liao, Zhe Zhao, Moshe Tur, Robert W. Boyd, Alan E. Willner

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

We experimentally demonstrate spatial multiplexing of an orbital angular momentum (OAM)-encoded quantum channel and a classical Gaussian beam with a different wavelength and orthogonal polarization. Data rates as large as 100 MHz are achieved by encoding on two different OAM states by employing a combination of independently modulated laser diodes and helical phase holograms. The influence of OAM mode spacing, encoding bandwidth, and interference from the co-propagating Gaussian beam on registered photon count rates and quantum bit error rates is investigated. Our results show that the deleterious effects of intermodal crosstalk effects on system performance become less important for OAM mode spacing Δ ≥ 2 (corresponding to a crosstalk value of less than −18.5 dB). The use of OAM domain can additionally offer at least 10.4 dB isolation besides that provided by wavelength and polarization, leading to a further suppression of interference from the classical channel.

Original languageEnglish
Pages (from-to)4881-4884
Number of pages4
JournalOptics Letters
Volume42
Issue number23
DOIs
StatePublished - 1 Dec 2017

Funding

FundersFunder number
Office of Naval ResearchN00014-15-1-2635

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