title: Crosstalk mitigation in a free-space orbital angular momentum multiplexed communication link using 4×4 MIMO equalization.
abstract: We demonstrate crosstalk mitigation using 4×4 multiple-input-multiple-output (MIMO) equalization on an orbital angular momentum (OAM) multiplexed free-space data link with heterodyne detection. Four multiplexed OAM beams, each carrying a 20  Gbit/s quadrature phase-shift keying signal, propagate through weak turbulence. The turbulence induces inter-channel crosstalk among each beam and degrades the signal performance. Experimental results demonstrate that with the assistance of MIMO processing, the signal quality and the bit-error-rate (BER) performance can be improved. The power penalty can be reduced by >4  dB at a BER of 3.8×10-3.
authors: Hao
authors: H
authors: Huang
authors: Yinwen
authors: Y
authors: Cao
authors: Guodong
authors: G
authors: Xie
authors: Yongxiong
authors: Y
authors: Ren
authors: Yan
authors: Y
authors: Yan
authors: Changjing
authors: C
authors: Bao
authors: Nisar
authors: N
authors: Ahmed
authors: Mark A
authors: MA
authors: Neifeld
authors: Samuel J
authors: SJ
authors: Dolinar
authors: Alan E
authors: AE
authors: Willner