Sub-terahertz transmissive reconfigurable intelligent surface for integrated beam steering and self-OOK-modulation
Dongfang Shen, Feng Lan, Luyang Wang, Tianyang Song, Munan Yang, Tianyu Hu, Yueting Li, Xiaolei Nie, Jiayao Yang, Shixiong Liang, Hongxin Zeng, Huifang Zhang, Pinaki Mazumder, Ziqiang Yang, Yaxin Zhang, Tie Jun Cui
Abstract
Boasting superior flexibility in beam manipulation and a simpler framework than traditional phased arrays, terahertz metasurface-based phased arrays show great promise for 5G-A/6G communication networks. Compared with the reflective reconfigurable intelligent surface (reflective RIS), the transmissive RIS (TRIS) offers more feasibility for transceiver multiplexing systems to meet the growing demand for high-performance beam tracking in terahertz communication and radar systems. However, the terahertz TRIS encounters greater challenges in phase shift, beam efficiency, and complex circuitry. Here, we propose a sub-terahertz TRIS based on the phase shift via Pancharatnam-Berry (PB) metasurface and self-on-off keying (OOK) modulation via Schottky diodes. The electrically reconfigurable unit cell consists of a column-wise phase resonator and a rectangular slot. An experimental retrieved equivalent lumped-element circuit model is implemented in joint field-circuit simulations and is validated by experiments. A fabricated prototype demonstrates excellent performance of TRIS with the minimum insertion loss of 2.8 dB for operational states, large bandwidth nearly covering the entire W-band for 1-bit phase shift, deep OOK amplitude modulation of 12 dB, and wide scanning range of ±60° with low specular transmission. We further implement an integrated platform combining high-speed beam steering and spatial-light modulation, verifying the point-to-point signal transmissions in different directions using the TRIS platform. The proposed TRIS with high-performance and cost-effective fabrication makes it a promising solution to terahertz minimalist communication systems, radar, and satellite communication systems.