Image transmission based on array superimposed OAM encoding
Abstract
<p indent="0mm">Array OAM-coded data transmission is a potential method to improve the information capacity and has important research value for realizing high-capacity optical communication. However, there are problems related to high system complexity and inflexible regulation. In this paper, an optical communication method and system for flexible tunable array multi-channel OAM-coded image transmission is proposed. In order to obtain an array beam, we first generate an array Gaussian beam using a specially designed Dammann grating instead of a conventional way of generating an array Gaussian beam through the combination of multiple beam-splitting prisms and mirrors, which reduces the complexity of the system. Subsequently, we obtained a 2×2 array vortex beam by designing an integrated vortex holographic grating and matching the generated array Gaussian beam. In our 2×2 array vortex setup, each subchannel of the array vortex beam can be freely and independently regulated, and the experimental setup is simple and easy to operate. Based on this, we built an array OAM-coded image transmission system to encode and transmit a 110-pixel×110-pixel 256-grayscale puppy image. The experimental results show that zero-BER (bit error rate) image recovery is achieved without any interference; in the presence of turbulence interference, the BER of image transmission is 0.001; in the presence of severe turbulence interference, the BER reaches 0.089. To address the problem of high transmission BER in harsh environments, in our future work, we will consider introducing a deep learning technique to improve the accuracy of the calculation of the bright ‘petals’ of the array, to reduce the BER and improve the transmission performance. In addition, the use of a 2×2 array optical mode expands the information capacity by a factor of 4 compared with the conventional single-channel optical coding data transmission method. In the follow-up work, <italic>m</italic>×<italic>m</italic> (<italic>m</italic>>2) array OAM-coded information transmission will be investigated to further improve the information capacity. The results of this research can provide an important reference for realizing high-capacity optical communication.</p>
