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.
|Title of host publication||SPIE Future Sensing Technologies|
|Editors||Masafumi Kimata, Joseph A. Shaw, Christopher R. Valenta|
|Publication status||Published - 2020|
|Event||SPIE Future Sensing Technologies 2020 - Virtual, Online, Japan|
Duration: 2020 Nov 9 → 2020 Nov 13
|Name||Proceedings of SPIE - The International Society for Optical Engineering|
|Conference||SPIE Future Sensing Technologies 2020|
|Period||20/11/9 → 20/11/13|
Bibliographical noteFunding Information:
This work was supported by the National Research Foundation (NRF) funded by the Korean Government under Grants NRF-2012R1A4A1029061 and 2015R1A2A1A10052826. The work of Sim E. was supported by the NRF under Grant NRF-2017R1A2B2003552.
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