Crosstalk mitigation using pilot assisted least square algorithm in OFDM-carrying orbital angular momentum multiplexed free-space-optical communication links.

In this paper, we experimentally investigate the performance of crosstalk mitigation for 16-ary quadrature amplitude modulation orthogonal frequency division multiplexing (16QAM-OFDM) signals carrying orbital angular momentum (OAM) multiplexed free-space-optical communication (FSO) links using the pilot assisted Least Square (LS) algorithm. At the demodulating spatial light modulators (SLMs), we launch the distorted phase holograms which have the information of atmospheric turbulence obeying the modified Hill spectrum. And crosstalk can be introduced by these holograms with the experimental verification. The pilot assisted LS algorithm can efficiently improve the quality of system performance, the points of constellations get closer to the reference points and around two orders of magnitude improvement of bit-error rate (BER) is obtained.

[1]  Ivan B Djordjevic,et al.  Deep-space and near-Earth optical communications by coded orbital angular momentum (OAM) modulation. , 2011, Optics express.

[2]  S. M. Zhao,et al.  Aberration corrections for free-space optical communications in atmosphere turbulence using orbital angular momentum states. , 2012, Optics Express.

[3]  B. Zheng,et al.  Improving the Atmosphere Turbulence Tolerance in Holographic Ghost Imaging System by Channel Coding , 2013, Journal of Lightwave Technology.

[4]  Y Tang,et al.  Coherent optical OFDM: theory and design. , 2008, Optics express.

[5]  E. Morfiadakis,et al.  The suitability of the von Karman spectrum for the structure of turbulence in a complex terrain wind farm , 1996 .

[6]  L. Andrews,et al.  Propagation of a Gaussian-beam wave through a random phase screen , 1997 .

[7]  Zhijun Zhao,et al.  Reed-Solomon coding for free-space optical communications through turbulent atmosphere , 2010, 2010 IEEE Aerospace Conference.

[8]  Larry C. Andrews,et al.  Effects of the refractive index spectral model on the irradiance variance of a Gaussian beam , 1994 .

[9]  A. Willner,et al.  Terabit free-space data transmission employing orbital angular momentum multiplexing , 2012, Nature Photonics.

[10]  A. Willner,et al.  Optical communications using orbital angular momentum beams , 2015 .

[11]  Robert W Boyd,et al.  Influence of atmospheric turbulence on states of light carrying orbital angular momentum. , 2012, Optics letters.

[12]  Moshe Tur,et al.  Turbulence compensation of an orbital angular momentum and polarization-multiplexed link using a data-carrying beacon on a separate wavelength. , 2015, Optics letters.

[13]  Jian Wang,et al.  Compensation of a distorted N-fold orbital angular momentum multicasting link using adaptive optics. , 2016, Optics letters.

[14]  A. Willner,et al.  Crosstalk mitigation in a free-space orbital angular momentum multiplexed communication link using 4×4 MIMO equalization. , 2014, Optics letters.

[15]  A. Willner,et al.  Adaptive optics compensation of multiple orbital angular momentum beams propagating through emulated atmospheric turbulence. , 2014, Optics letters.

[16]  Yinwen Cao,et al.  Phase correction for a distorted orbital angular momentum beam using a Zernike polynomials-based stochastic-parallel-gradient-descent algorithm. , 2015, Optics letters.