Broadband opto-thermal camouflage and infrared encrypted communication via inverse design.

Multispectral detection technologies spanning optical and thermal bands pose a severe threat to military camouflage while simultaneously unlocking new opportunities for covert communication. However, smart materials capable of both countering these threats and exploiting these bands for communication are still lacking. Here, using a Bayesian-optimization-based inverse-design strategy, we propose an opto-thermally decoupled photonic structure. It features broadband optical camouflage across the 0.38-2.5 μm range, encompassing the visible, near-infrared, and short-wave infrared bands (including the 1.55 μm laser wavelength), with a tunable structural-color palette that covers 66% of the CMYK gamut. Crucially, while these colors are independently tunable, the structure modulates radiance in the mid-wave infrared (MWIR) and long-wave infrared (LWIR) bands for dynamic thermal camouflage, achieving consistent MWIR/LWIR emissivity switching between 0.41 ± 0.04/0.90 ± 0.01 and 0.93 ± 0.03/0.45 ± 0.01 driven by the vanadium dioxide (VO₂) phase transition. Beyond camouflage, by precisely regulating the temperature, we exploit the differential MWIR/LWIR thermal signatures generated by the continuous phase evolution of VO₂ to encode information for infrared encrypted communication. We experimentally demonstrate the structure's dual capabilities for broadband opto-thermal concealment and covert communication. This work integrates multispectral camouflage and covert communication within a single platform, offering a new design strategy for next-generation military smart materials.