Multidimensional demultiplexing of underwater broadband synthesized acoustic vortex beams via a binary-amplitude coded metademultiplexer
Phys. Rev. Applied 25, 054040 – Published 15 May, 2026
DOI: https://doi.org/10.1103/9mps-dzmr
Abstract
Achieving accurate and rapid sorting of orbital angular momentum (OAM) modes in synthesized acoustic vortex beams plays a pivotal role in OAM-harnessing underwater acoustic communication. However, most existing studies distinguish OAM modes alone and are performed predominantly in airborne environments, while lacking the capability to simultaneously demodulate other dimensions of sound waves, such as frequency. Here we propose the design and experimental realization of a monolayered metademultiplexer with subwavelength thickness for multidimensional demultiplexing across both the OAM domain and the frequency domain of underwater acoustic vortex beams via a binary-amplitude modulation strategy. By imposing a theoretically derived nondispersive binary-amplitude profile, the metademultiplexer comprising only two simple units is imprinted with OAM selectivity and a chromatic aberration characteristic, enabling it to untwist and focus multifrequency and multimode underwater vortex beams into the designated spatially separated detection points within three-dimensional space behind the device. Thanks to this effective mapping between the spatial location and the spectral and OAM modes, the high-capacity OAM and frequency information can be simultaneously demultiplexed in a passive, real-time, and flexible way, while the proposed method remains compatible with conventional demultiplexing techniques harnessing other physical dimensions. The metademultiplexer is implemented with ultrathin acoustically rigid material with high-pressure resistance, and its effectiveness is validated through both numerical simulation and underwater experimental measurement, demonstrating high-accuracy demodulation of spatially and spectrally multiplexed acoustic vortex beams with interchannel crosstalk below −20 dB. We envision that our binary amplitude–coded demultiplexing strategy offers a promising pathway toward the development of advanced OAM-based acoustic information processing devices.
