中文

Journal of Shanghai University（Natural Science Edition） ›› 2017, Vol. 23 ›› Issue (5): 658-665.doi: 10.12066/j.issn.1007-2861.1761

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Demodulation for multi vortex beams based on composite diffraction hologram

WANG Yingying, LI Yingchun, SHAO Wei, ZHANG Weibin, SUN Tengfen, ZHU Fuquan   

  1. School of Communication and Information Engineering, Shanghai University, Shanghai 200444, China
  • Received:2016-01-08 Online:2017-10-30 Published:2017-10-30

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Abstract:

When projecting a Gauss beam onto the spatial light modulator (SLM) loaded with a composite hologram, several vortex beams are generated simultaneously. On the contrary, when projecting the corresponding vortex beam onto a hologram, the Gauss beam can be restored, realizing demodulation of the vortex beam. Traditionally, a hologram can only demodulate one incident vortex beam. In this paper a vortex beam demodulation method based on composite diffraction hologram that can demodulate several incident vortex beams with only one hologram is proposed, thus having a good chance of applications. An experimental system is set up to achieve generation, transmission and demodulation of vortex beams with 16 quadrature amplitude modulation-orthogonal frequency division multiplexing (QAM-OFDM) signals. After offline processing on the demodulated Gauss beam, constellation and bit error rate of each subcarrier for OFDM signals are acquired. The experiment results show that the bit error rates of all subcarriers are below the forward error correction (FEC) threshold.

Key words: 16 quadrature amplitude modulation (QAM), composite diffraction hologram, vortexbeam, orthogonal frequency division multiplexing (OFDM)