Phase-Change Grating Multispectral Camouflage System for Security Applications: Dynamic Regulation and Information Encryption

Traditional infrared camouflage materials often suffer from limitations in multispectral compatibility, fixed emissivity, and angular sensitivity, which restrict their effectiveness against advanced detection technologies. To address these challenges, a laser-programmable Ge₂Sb₂Te₅ ${\mathrm{Ge}}_2{\mathrm{Sb}}_2{\mathrm{Te}}_5$ (GST)/Ag grating surface capable of dual-band infrared camouflage with suppressed thermal emission is proposed. This design achieves remarkably low emissivity values of 0.12 in the mid-wave infrared (MWIR) and 0.04 in the long-wave infrared (LWIR) bands. Through laser-induced gradient crystallization, continuous emissivity modulation in the LWIR band is demonstrated, enabling dynamic spectral control. By integrating a visible-transparent and infrared-nondestructive (Si₃N₄ ${\mathrm{Si}}_3{\mathrm{N}}_4$) coating, multispectral stealth across visible and infrared wavelengths is achieved. The highly symmetric grating architecture ensures polarization insensitivity and angular robustness, maintaining performance over a wide incidence range (0 ${}^{\circ }$–60 ${}^{\circ }$). Furthermore, by integrating laser-written infrared patterns with color layers and utilizing nanoscale grating height variations ($\pm 20$ nm) combined with crystal structure replication technology, a multilevel information encryption system is achieved. The system achieves information encryption and controllable elimination through infrared-responsive writing and erasing operations, significantly enhancing security performance. The coordinated material and architectural design approach offers a scalable platform with multifunctional capabilities for military camouflage and optical security applications.