Orbital angular momentum recognition in complex scattering media

Mode recognition of orbital angular momentum (OAM) beams is important in OAM applications. However, scattering media can cause severe crosstalk between OAM modes, reducing the accuracy of OAM mode recognition. In this paper, we report a method based on single-pixel detection to realize OAM recognition and transmission in complex scattering media. At the transmitter, we select three Laguerre-Gaussian (LG) beams as the encoding bases. Each transmitted data is encoded as a combination of three bases. Then, OAM beams are modulated by a series of pre-designed patterns to propagate in a complex scattering environment. At the receiving end, a single-pixel detector is used to detect the intensities of OAM beams. The intensity distortion introduced by scattering media is corrected by using the alternating projection method, thereby reconstructing high-quality OAM images. By calculating correlation coefficients between the reconstructed OAM image and the OAM images in a lookup table, the OAM modes can be accurately recognized, and the transmitted data can be correctly decoded. Experimental results demonstrate that this method can reconstruct high-quality OAM images in complex scattering environments and achieve accurate recognition and transmission of OAM beams.