A space‐time coding metasurface (STCM) operating in the sub‐terahertz band to construct new‐architecture wireless communication systems is proposed. Specifically, a programmable STCM is designed with varactor‐diode‐tuned metasurface elements, enabling precise regulation of harmonic amplitudes and phases by adjusting the time delay and duty cycle of square‐wave modulation signal loaded on the varactor diodes. Independent electromagnetic (EM) regulations in the space and time domains are achieved by STCM to realize flexible beam manipulations and information modulations. Based on these features, a sub‐terahertz wireless communication link is constructed by employing STCM as a transmitter. Experimental results demonstrate that the STCM supports multiple modulation schemes including frequency‐shift keying, phase‐shift keying, and quadrature amplitude modulations in a wide frequency band. It is also shown that the STCM is capable of realizing wide‐angle beam scanning in the range of ±45^o, which offers an opportunity for user tracking during the communication. Thus, the STCM transmitter with high device density and low power consumption can provide low‐complexity, low‐cost, low‐power, and low‐heat solutions for building the next‐generation wireless communication systems in the sub‐terahertz frequency and even terahertz band.

In this paper, an approach is proposed toward two-dimensional (2D) beam tailoring in the terahertz band based on programmable metasurface loaded with liquid crystals. Specifically, a 1-bit reflective metasurface element is designed with switchable phase responses, and subsequently, an individually controllable metasurface array in 2D fashion is achieved by pixelating the metallic reflection back plate. As typical examples, programmable metasurfaces operating around 94 and 220 GHz are developed, respectively, and both simulation and experimental results confirm the powerful abilities of the metasurfaces in 2D wide-angle beam manipulations. In addition, the proposed method has advantages of wide frequency range, low cost, and high reliability, implying significant application prospects in terahertz reconfigurable intelligent surfaces and holographic imaging.

The terahertz magnetic properties of perovskite-like SmFeO₃ ceramic are investigated over a broad temperature range, especially at ultralow temperatures, using terahertz time-domain spectroscopy. It is shown that both resonant frequencies of quasi-ferromagnetic and quasi-antiferromagnetic modes have blue shifts with the decreasing temperature due to the enhancement of effective magnetic field. The temperature-dependent magnetic anisotropy constants are further estimated using the resonant frequencies, under the approximation of omitting the contribution of Sm³⁺ magnetic moments to the effective field. Specially, the effective anisotropy constants in the ca and cb planes at 3 K are 6.63 × 10⁵ erg/g and 8.48 × 10⁵ erg/g, respectively. This thoroughly reveals the terahertz magnetic thermodynamics of orthoferrites and will be beneficial to the application in terahertz magnetism.