Characterization of Orbital Angular Momentum Applying Single-Sensor Compressive Imaging Based on a Microwave Spatial Wave Modulator

In this work, a new technique to characterize a microwave orbital angular momentum (OAM) beam applying a single-sensor compressive imaging (SSCI) strategy is reported, which is much more time-efficient, cost-effective, and compact than traditional near-field scanning methods. A microwave spatial wave modulator (MSWM) realized by a programmable metasurface is applied to generate random mask patterns and modulate an OAM beam under test. The modulated fields are collected by a single-sensor detector. Two different algorithms can be used to reconstruct phase and magnitude profiles of the OAM beam, with the first one demands both amplitude and phase measurement while the second one only perceives the amplitude or intensity. Simulations are first carried out to investigate the effects of several parameters of the random mask patterns on the quality of reconstruction. Proof-of-concept experiments are then performed to characterize a microwave OAM beam, and obtained results show high-quality reconstructed phase and magnitude distributions of the OAM beam under test, which corroborates the effectiveness of the proposed SSCI technique. This work establishes an alternative paradigm for fast and economic measurement of microwave and millimeter-wave OAM beams. It may also facilitate OAM-based communication applications.