IEEE Access (Jan 2019)

Convolutional Neural Network-Assisted Optical Orbital Angular Momentum Recognition and Communication

  • Peipei Wang,
  • Junmin Liu,
  • Lijuan Sheng,
  • Yanliang He,
  • Wenjie Xiong,
  • Zebin Huang,
  • Xinxing Zhou,
  • Ying Li,
  • Shuqing Chen,
  • Xiaomin Zhang,
  • Dianyuan Fan

DOI
https://doi.org/10.1109/ACCESS.2019.2951579
Journal volume & issue
Vol. 7
pp. 162025 – 162035

Abstract

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The identification of orbital angular momentum (OAM) modes with high-accuracy and -speed is always a difficult issue in practically applying optical vortex beams (OVs). In this work, we propose and experimentally investigate a convolutional neural network (CNN) method for optical OAM mode identification and shift-keying (SK) communications. The CNN model, including convolution and pooling layers, was designed to extract mode information from the diffraction patterns produced by diffracting the OVs with a cylindrical lens. After trained with loads of studying samples, the CNN model has a good generation ability in recognizing the OAM modes of OVs ranging from -15 to 15. The recognition accuracy reaches 99% with the turbulence intensity of Cn2 = 1 × 10-13m-2/3, Δz = 50 m. Even under the turbulence of Cn2 = 1 × 10-12 m-2/3, Δz = 50 m, the accuracy still exceeds 89%. By mapping and encoding a Lena gray image with the size of 100 × 100 pixels to two OAM channels, the OAM-SK signals with 900 modulation orders were successfully demodulated by the CNN model, and the image was well recovered after transmission. With an I5-8500 Central Processing Unit, this recognition process only takes 1 ×10-3 s per mode. It is anticipated that the CNN methods might provide an effective way for identifying OAM modes with high-accuracy and -speed, which may have great potentials in OAM communication, quantum information processing, and astronomical application, etc.

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