Broadband achromatic illusion via a transmission-reflection-integrated metasurface.

Illusion metasurfaces provide an effective route to reshape the electromagnetic signature of a physical object into that of a prescribed virtual target, but most existing designs are restricted to either reflection or transmission and suffer from large chromatic aberrations that hinder broadband operation. Here, we present a transmission-reflection-integrated metasurface (TRIM) for broadband achromatic illusion camouflage. The metasurface is implemented with a polarization-dependent multilayer meta-atom, in which resonant phase modulation and geometric phase control are cascaded to provide full phase coverage in the cross-polarized transmission channel and the co-polarized reflection channel while maintaining broadband achromatic responses. Experimental results demonstrate transmissive illusion over 12-18 GHz (fractional bandwidth 40%) and reflective illusion over 18-24 GHz (fractional bandwidth 28.6%) within a single platform. The proposed approach has promising implications for optical information processing, stealth, and integrated photonic systems.