The mechanism of optical chirality enhancement in vertical-cut slant-gap antenna

The mechanism of optical chirality enhancements (OCE) in slant-gap antenna with vertical-cut configuration by normal and oblique incident light with linear polarization is demonstrated. The main contribution of OCE is originated from the inner product of the incident H field and the localized surface plasmon resonant (LSPR) evanescent E field. The pure LSPR near-field term E·H gives a net zero contribution. Based on these findings, we can accurately count for the asymmetric OCE distribution due to the substrate effect. The detailed analysis of OCE contribution might provide a route for designing a more efficient chiral molecule sensor.