Surface plasmon resonance phase interrogation is assumed to be more sensitive than intensity or wavelength interrogation. We propose for the first time theoretical and numerical studies of the phase in surface plasmon resonance sensor and establish a quantitative relation between phase sensitivity and wavelength interrogation. We reveal the link between ultra-high phase sensitivity and critical coupling condition. However, reaching this condition requires a technically infeasible angstrom-level precision in the metal layer thickness. We propose a robust solution to overcome this limitation by coupling the SPR with a phase-change material (PCM) thin film. By exploiting the multilevel reconfigurable phase states of PCM, we theoretically demonstrate ultra-high phase sensitivities with a limit of detection as low as 10⁻¹⁰ refractive index unit (RIU). Such a PCM-assisted SPR sensor platform paves the way for unprecedented sensitivity sensors for the detection of trace amounts of low molecular weight species in biomedical sensing and environmental monitoring.

中文翻译：

---

通过调整与相变材料的关键耦合，实现表面等离子体共振传感器的终极相位灵敏度

假设表面等离子体共振相位询问比强度或波长询问更敏感。我们首次提出了表面等离子体共振传感器中相位的理论和数值研究，并建立了相位灵敏度和波长询问之间的定量关系。我们揭示了超高相位灵敏度和临界耦合条件之间的联系。然而，达到这种条件需要技术上不可行的金属层厚度埃级精度。我们提出了一种强大的解决方案，通过将 SPR 与相变材料 (PCM) 薄膜耦合来克服这一限制。通过利用 PCM 的多级可重构相态，我们在理论上证明了超高的相位灵敏度，检测限低至 10 ^-10折射率单位 (RIU)。这种 PCM 辅助 SPR 传感器平台为前所未有的灵敏度传感器铺平了道路，用于检测生物医学传感和环境监测中的痕量低分子量物种。