Orbital Angular Momentum-based Space Division Multiplexing for High-capacity Underwater Optical Communications.
To increase system capacity of underwater optical communications, we employ the spatial domain to simultaneously transmit multiple orthogonal spatial beams, each carrying an independent data channel. In this paper, we show up to a 40-Gbit/s link by multiplexing and transmitting four green orbital angular momentum (OAM) beams through a single aperture. Moreover, we investigate the degrading effects of scattering/turbidity, water current, and thermal gradient-induced turbulence, and we find that thermal gradients cause the most distortions and turbidity causes the most loss. We show systems results using two different data generation techniques, one at 1064 nm for 10-Gbit/s/beam and one at 520 nm for 1-Gbit/s/beam; we use both techniques since present data-modulation technologies are faster for infrared (IR) than for green. For the 40-Gbit/s link, data is modulated in the IR, and OAM imprinting is performed in the green using a specially-designed metasurface phase mask. For the 4-Gbit/s link, a green laser diode is directly modulated. Finally, we show that inter-channel crosstalk induced by thermal gradients can be mitigated using multi-channel equalisation processing.
Department of Electrical Engineering, University of Southern California, Los Angeles, CA 90089, USA.
Yongxiong
Y
Ren
Department of Electrical Engineering, University of Southern California, Los Angeles, CA 90089, USA.
Long
L
Li
Department of Electrical Engineering, University of Southern California, Los Angeles, CA 90089, USA.
Zhe
Z
Wang
T. J. Watson Laboratory of Applied Physics, California Institute of Technology, Pasadena, CA 91125, USA.
Seyedeh Mahsa
SM
Kamali
T. J. Watson Laboratory of Applied Physics, California Institute of Technology, Pasadena, CA 91125, USA.
Ehsan
E
Arbabi
T. J. Watson Laboratory of Applied Physics, California Institute of Technology, Pasadena, CA 91125, USA.
Amir
A
Arbabi
Department of Electrical Engineering, University of Southern California, Los Angeles, CA 90089, USA.
Zhe
Z
Zhao
Department of Electrical Engineering, University of Southern California, Los Angeles, CA 90089, USA.
Guodong
G
Xie
Department of Electrical Engineering, University of Southern California, Los Angeles, CA 90089, USA.
Yinwen
Y
Cao
Department of Electrical Engineering, University of Southern California, Los Angeles, CA 90089, USA.
Nisar
N
Ahmed
Department of Electrical Engineering, University of Southern California, Los Angeles, CA 90089, USA.
Yan
Y
Yan
Department of Electrical Engineering, University of Southern California, Los Angeles, CA 90089, USA.
Cong
C
Liu
Department of Electrical Engineering, University of Southern California, Los Angeles, CA 90089, USA.
Asher J
AJ
Willner
NxGen Partners, Dallas, TX75219, USA.
Solyman
S
Ashrafi
School of Electrical Engineering, Tel Aviv University, Ramat Aviv 69978, Israel.
Moshe
M
Tur
T. J. Watson Laboratory of Applied Physics, California Institute of Technology, Pasadena, CA 91125, USA.
Andrei
A
Faraon
Department of Electrical Engineering, University of Southern California, Los Angeles, CA 90089, USA.
Alan E
AE
Willner