Fig. 1.

(a) The traditional LSPR based sensing method based on nano-plasmonic resonator either in solution or substrate form. Spectral transform provides resonant frequency signature to distinguish between biomolecular binding or no binding event. (b) Proposed spectrum free (monochromatic) polarization state sensitive biosensing method where linearly x-polarized electric field impinges on dispersion engineered chiral LSPR metasurface. Three different reflected signals left ($R_1$)/right ($R_3$) handed elliptical and linearly y-directional polarized ($R_2$) are provided as examples. (c) Reversible polarization states supported by metasurface i.e., left hand (LH) or right hand (RH) ellipses along with orientation angle (θ) due to variation in RI ($n_1$, $n_2$, $n_3$) of the target analyte. (d) Polarization ellipses for incident and reflected signals $R_1$, $R_2$ and $R_3$ in $xy$-plane.