Recently, a remarkable advancement has been made by Professor Si Liming's research team from the School of Integrated Circuits and Electronics at Beijing Institute of Technology (BIT). Collaborating with Professor Yang Fan of Tsinghua University and Associate Professor Zhu Weiren of Shanghai Jiao Tong University, the team has achieved significant strides in the realm of microwave three-dimensional (3D) holographic imaging and multi-channel information encryption. Their related research findings have been published in two papers in the IEEE Transactions on Antennas and Propagation, a prestigious journal in the field of antennas and propagation.

The research overcomes the constraints of traditional metasurfaces, which typically depend on amplitude and phase within a two-dimensional plane for information encoding. By introducing the propagation direction and distance as supplementary dimensions for information encoding, the team has substantially increased the degrees of freedom in electromagnetic information manipulation. This breakthrough paves the way for new technical approaches in asymmetric 3D holographic imaging, multi-dimensional information multiplexing, and high-capacity optical information processing.

Moreover, the team has integrated orbital angular momentum (OAM) into the holographic information encoding and encryption process. They leverage different OAM topological charge modes to establish distinguishable information channels, thereby enhancing both the information capacity and physical-layer information security capabilities of metasurface holography. This innovative method enables the collaborative exploitation of multi-dimensional information resources, encompassing space, propagation, and modes, and pushes the capacity limits of traditional two-dimensional amplitude-phase encoding.

The research outcomes are anticipated to have a pivotal impact in various fields, including high-security holographic encryption, high-density information storage, space-division multiplexing wireless communications, novel electromagnetic displays, and cyber-physical fusion systems.