Tailoring Adhesion Interfaces for Perfect Absorption and Mechanical Stability of Optical Metasurfaces

Gold film-based zero-reflection metasurfaces show significant potential for advanced optical applications, including topologically controlled laser-like thermal emission. However, most proof-of-concept studies overlook the mechanical stability provided by adhesion layers, frequently refraining from their use since they disrupt the zero-reflection condition and degrade optical performance.

In this work, we aim to offer aluminium (Al) as a superior adhesion material for thin gold films that preserves both reflection intensity and resonance quality with high mechanical stability. We conclude that Al adhesion layer does not deteriorate the optical performance and provides near-electric field responses comparable to devices without adhesion layers. The advanced optical properties brought by Al are further demonstrated through the ultrasensitive detection of protein monolayers with higher sensitivities compared to other adhesive metals. We show that the metasurfaces maintain structural integrity under harsh water flow (50 ul/min) and sonication (40 kHz, 180 W) without delamination. More importantly, we conclude that the percolation threshold and native oxide formation play significant role for conserving the optical quality of devices. Our perspective is to offer a trusted pathway for transferring the exceptional optical properties of gold metal thin films to daily life usage. We present one of the best available solutions that simultaneously brings high robustness and high optical quality.