Phase noise matching in resonant metasurfaces for intrinsic sensing stability.

Interferometry offers a precise means of interrogating resonances in dielectric and plasmonic metasurfaces, surpassing spectrometer-imposed resolution limits. However, interferometry implementations often face complexity or instability issues due to heightened sensitivity. Here, we address the necessity for noise compensation and tolerance by harnessing the inherent capabilities of photonic resonances. Our proposed solution, termed "resonant phase noise matching," employs optical referencing to align the phases of equally sensitive, orthogonal components of the same mode. This effectively mitigates drift and noise, facilitating the detection of subtle phase changes induced by a target analyte through spatially selective surface functionalization. Validation of this strategy using Fano resonances in a 2D photonic crystal slab showcases noteworthy phase stability ( σ < 10 - 4 π ). With demonstrated label-free detection of low-molecular-weight proteins at clinically relevant concentrations, resonant phase noise matching presents itself as a potentially valuable strategy for advancing scalable, high-performance sensing technology beyond traditional laboratory settings.