Orbital Angular Momentum Transmission in Complex Environments Using a Single-Pixel Detector

Light carrying orbital angular momentum (OAM) has attracted much attention in data transmission. However, dynamic and complex scattering in real-world scenarios could affect intensity and phase distributions of OAM beams, leading to severe crosstalk in the received data. Here, we report OAM transmission in complex and dynamic scattering environments using a single-pixel detector. The transmitted data is first encoded by using two Laguerre-Gaussian (LG) beams. The OAM beam has a petal-like structure, and the total number of petals is designed to be equivalent to the transmitted data. Then, the OAM beam is modulated by a series of random patterns followed by wave propagation through complex and dynamic scattering media in a free-space optical channel. At the receiving end, an alternating projection method is developed to correct dynamic scaling factors and recover high-quality OAM intensity patterns based on the series of light intensities collected by a single-pixel detector. The recovered OAM intensity patterns are further used to decode the transmitted data using polar coordinate expansion and peak counting. Experimental results demonstrate that our method can eliminate the influence of complex and dynamic scattering with a reconstruction of high-quality OAM intensity patterns from the distorted measurements, and accurate recognition of light beams carrying OAM can always be achieved in complex environments. This work paves the way for OAM applications in harsh environments.