Ultrasensitive and Label-free Plasmonic Detection based on Singular Phase Signal Changes

A study of phase-sensitive surface plasmon resonance detection through enhanced optical signal changes by ultrathin nanomaterials is presented. The precise tuning of metallic substrate and phase change material-coated substrate for strong plasmon excitation were systematically investigated via both experimental measurements and theoretical calculations. The evaluations of different plasmonic sensing substrates were carried out through angular and phase-related position scanning methods. The sensing performances of Au and Ge
₂
Sb
₂
Te
₅
(GST) thin films have been compared especially in terms of the phase singularity-related position shifts induced by the targeted sample solutions. These results paved a way for the development of stable and ultrasensitive plasmonic devices for clinical diagnostic and environmental monitoring applications.