Characterization of surface plasmon resonance detection based on the colocalization effect inside metallic nanogap

Changhun Lee, Eunji Sim, Donghyun Kim

Research output: Chapter in Book/Report/Conference proceedingConference contribution


We have studied how the light-matter colocalization effect, which is the overlap effect between target and electric field distribution, affects the sensitivity of nanogap-based surface plasmon resonance (SPR) sensors. The SPR characteristics of the nanogap structure were calculated using a rigorous coupled-wave analysis program with DNA immobilization and hybridization cases. The colocalized shift (COS) and its relative value, relative optical signature (ROS), were defined to explain the capability change according to the gap size (g) along with the momentum matching condition of the nanogap. The maximum sensitivity, defined as the COS value compared to the changed refractive index, was 514.8 deg / (μm ∗ RIU), which appeared at a relatively large interval (g = 17nm). When increasing the nanogap size, the ROS and reflectance also increased. However, the trend reversed, and the decrease in ROS reached a negative range at a 9 nm gap or more. This ROS is due to damping in the multiple localized surface plasmon polariton mode, and the strong field confinement inside the nanogap induces a negative shift. The zero-shift, the most avoidable when designing an SPR sensor, and near-field distribution with plasmon mode, is observed across different gap size and period pairs. The effect of colocalization inside the nanogap, as identified through various metrics, promises a highly sensitive detection potential for biological applications.

Original languageEnglish
Title of host publicationSPIE Future Sensing Technologies
EditorsMasafumi Kimata, Joseph A. Shaw, Christopher R. Valenta
ISBN (Electronic)9781510638617
Publication statusPublished - 2020
EventSPIE Future Sensing Technologies 2020 - Virtual, Online, Japan
Duration: 2020 Nov 92020 Nov 13

Publication series

NameProceedings of SPIE - The International Society for Optical Engineering
ISSN (Print)0277-786X
ISSN (Electronic)1996-756X


ConferenceSPIE Future Sensing Technologies 2020
CityVirtual, Online

Bibliographical note

Publisher Copyright:
Copyright © 2020 SPIE.

All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Computer Science Applications
  • Applied Mathematics
  • Electrical and Electronic Engineering


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