Improving the demultiplexing performances of the multiple Bessel Gaussian beams (mBGBs)

• Published in: Results in physics 2021-11, Vol.30, p.104829, Article 104829
• Main Authors: Gong, Chaofan, Pan, Zhenzhen, Dedo, Maxime Irene, Sun, Jinghua, Wang, Lulu, Guo, Zhongyi
• Format: Article
• Language: English
• Subjects: Bessel Gaussian (BG) beams; Free-space optical (FSO) communication; Helical phase; Multiple Bessel Gaussian beams (mBGBs); Multiplexing phase hologram (MPH); Orbital angular momentum (OAM)
• ISSN: 2211-3797; 2211-3797
• DOI: 10.1016/j.rinp.2021.104829

•Demodulate multiplexing BG beams with multiple OAM states efficiently.•Improve pinhole plate to average the center energy distribution.•32-OAM states (±18 ∼ ±3) were selected to encode the four ACSII codes. As approximate non-diffracted beams, Bessel Gaussian (BG) beams are more suitable to be used in free-space optical (FSO) communication system than Laguerre Gaussian (LG) vortex beams because of its self-recovering property. However, due to the limitation of its detection method, the multiplexing communication based on multiple Bessel Gaussian beams (mBGBs) has not been investigated deeply. In this paper, we propose a method for simultaneous demodulation of 36-mBGBs using 6 × 6 multiplexing phase hologram (MPH). To solve the problem that the energy of some BG beams are too low at the demodulation end, a method is proposed to optimize the pinhole size of the pinhole plate at the demodulation end. Compared with the traditional decomposition method, the proposed method not only improves the decoding efficiency greatly, but also has better robustness. In addition, the communication performance of 32-mBGBs encoded with four ASCII codes has been constructed and investigated numerically. The results show that the transmitted information can be clearly decoded by setting a reasonable threshold value, which is beneficial to the practical application of mBGBs in FSO communications.