Experimental mitigation of the effects of the limited size aperture or misalignment by singular-value-decomposition-based beam orthogonalization in a free-space optical link using Laguerre–Gaussian modes

Kai Pang, Haoqian Song, Xinzhou Su, Kaiheng Zou, Zhe Zhao, Hao Song, Ahmed Almaiman, Runzhou Zhang, Cong Liu, Nanzhe Hu, Shlomo Zach, Nadav Cohen, Brittany Lynn, Andreas F. Molisch, Robert W. Boyd, Moshe Tur, Alan E. Willner

Research output: Contribution to journalArticlepeer-review

12 Scopus citations

Abstract

Limited-size receiver (Rx) apertures and transmitter–Rx (Tx–Rx) misalignments could induce power loss and modal crosstalk in a mode-multiplexed free-space link. We experimentally demonstrate the mitigation of these impairments in a 400 Gbit/s four-data-channel free-space optical link. To mitigate the above degradations, our approach of singular-value-decomposition-based (SVD-based) beam orthogonalization includes (1) measuring the transmission matrix H for the link given a limited-size aperture or misalignment; (2) performing SVD on the transmission matrix to find the U, 6, and V complex matrices; (3) transmitting each data channel on a beam that is a combination of Laguerre–Gaussian modes with complex weights according to the V matrix; and (4) applying the U matrix to the channel demultiplexer at the Rx. Compared with the case of transmitting each channel on a beam using a single mode, our experimental results when transmitting multi-mode beams show that (a) with a limited-size aperture, the power loss and crosstalk could be reduced by ∼8 and ∼23 dB, respectively; and (b) with misalignment, the power loss and crosstalk could be reduced by ∼15 and ∼40 dB, respectively.

Original languageEnglish
Pages (from-to)6310-6313
Number of pages4
JournalOptics Letters
Volume45
Issue number22
DOIs
StatePublished - 15 Nov 2020
Externally publishedYes

Bibliographical note

Publisher Copyright:
© 2020 Optical Society of America

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