Periodic “L”-shaped grating metasurface for VIS-infrared-laser compatible camouflage

In response to the growing threat posed by multispectral detectors, it is of urgent significance to achieve simultaneous camouflage compatibility across the visible (VIS), mid-wave infrared (MWIR), long-wave infrared (LWIR) bands, and the 10.6 μm laser wavelength. Here, we propose an “L”-shaped grating metasurface emitter stacked of S1818/Al/Mo/ZnS multilayers. Based on thin-film interference in the multilayer stack, the metasurface can be tuned to exhibit a range of structural colors in the visible region. Under orthogonal polarization illumination, the "L"-shaped grating generates a reflection phase difference close to 180°, resulting in the low specular reflectance required for laser radar camouflage (the specular reflectance at 10.6 μm is 0.05). Meanwhile, due to the excellent reflective properties of the Al layer, the metasurface exhibits low average emissivity in the MWIR (ɛ_3–5μm≈0.026) and LWIR (ɛ_8–14μm = 0.019) ranges, effectively reducing infrared detectability. Experimental results show that the sample exhibits a specular reflectance of 0.16 at the 10.6 μm. The average emissivity is 0.06 in the MWIR (3–5 μm) band and 0.09 in the LWIR (8–14 μm) band, validating the good compatible camouflage capability both for the infrared bands and the 10.6 μm laser wavelength. Moreover, the structural colors in the visible range closely resemble those of natural objects. This work demonstrates the feasibility of the “L”-shaped grating metasurface multispectral camouflage design strategy.