Polarization-sensitive photothermal effects of a ZrN plasmonic metamaterial absorber with isotropic absorption

Polarization-dependent photothermal effects in plasmonic nanostructures hold promise for applications like polarization-encoded thermal signaling, but conventional approaches rely on anisotropic absorption and are vulnerable to polarization perturbations. Here, we report unconventional polarization-sensitive photothermal effects in a zirconium nitride (ZrN) plasmonic metamaterial absorber that exhibits nearly polarization-independent absorption. Despite minimal absorption variation (≤0.1%), significant polarization-induced temperature differences of 5 K are achieved. This photothermal anisotropy originates from polarization-dependent near-field localization and subsequent joule heating at the sharp corners of square prisms. Furthermore, we show that photothermal anisotropy can be regulated through structural symmetry, providing a design framework for polarization-sensitive plasmonic platforms.