Thermal radiation, as an information carrier inherently present in physical processes, offers a channel for mid-infrared information transmission. Precise control over emissivity within the atmospheric transparency windows—specifically the mid-wave infrared (MWIR) 3–5 μm and long-wave infrared (LWIR) 8–14 μm bands—holds the key to enabling information encoding and transmission. While existing dynamic modulation techniques suffer from limitations such as high-power consumption and unstable intermediate states, non-volatile phase-change materials (PCMs) offer the advantage of maintaining encoded states without standby power. However, their emissivity states vary monotonically with crystallinity and remain limited in number, falling short of the requirements for high-density information storage and complex encryption.
Recently, a research team led by Professor Junbo Yang at the National University of Defense Technology has proposed a novel permittivity regulation framework based on programmable interface atomic rearrangement. They developed an Ag-In₃SbTe₂ (IST) interface atomic rearrangement metamaterial (ARM), enabling full-spectrum and time-domain dynamic modulation, as well as spatiotemporal thermal radiation tailoring. The ARM exhibits broad and continuous spectral tunability, with modulation amplitudes reaching 64.74% in the 3-5 μm band and 73.94% in the 8-14 μm band, accompanied by rich temporal variations. This approach offers new insights into infrared radiation customization and information encryption within the realm of thermal photonics（Fig. 1）.
Research Progress
By ARM, thermally induced atomic migration enables continuous tunability of the mixed-layer permittivity. This mechanism provides three key advantages: high emissivity modulation amplitude, heating-rate-dependent tunability, and non-volatile state retention.
Through equivalent modeling and simulations, it was found that an Ag volume filling fraction approaching 0.5 defines the primary optical loss region, with increasing mixed-layer thickness leading to enhanced absorption. Crucially, the atomic rearrangement process operates on a slower timescale than phase change, enabling independent modulation of the top IST phase state and the bottom interface rearrangement—thus offering multi-dimensional control.
In application demonstrations, laser writing enabled multi-bit infrared pattern storage and dynamic display. For encryption, the images transition gradually from blurred to clear upon heating, allowing sequential decryption. Furthermore, by incorporating a dual-key mechanism—requiring specific heating durations and pattern sequences—spatiotemporal information encryption with enhanced security is achieved.
Future Prospects
This research overcomes the discrete-state limitations inherent in conventional thermal photonics through the introduction of the Ag–In₃SbTe₂ (IST) interface atomic rearrangement metamaterial (ARM). A comprehensive theoretical framework- spanning equivalent modeling, simulation, and experimental validation of atomic-scale mechanisms- has been established, enabling spatiotemporal and continuously programmable thermal radiation customization. Future work may explore several promising directions: stimulating atomic rearrangement via multi-physical field coupling (e.g., electric and magnetic fields), broadening the material palette by integrating diverse metal/phase-change material combinations, and constructing a multidimensional permittivity database spanning all relevant degrees of freedom. The ultimate vision is to achieve ultra-broadband, high-resolution spatiotemporal spectral engineering across the ultraviolet to microwave regimes, thereby establishing a versatile platform for advancing research in photonics and thermal radiation.
The complete study is accessible via DOI:10.34133/research.1141