We investigated the near-field enhancement of a localized surface plasmon resonance (LSPR) structure based on gold nanograting pairs with a nanosized gap. The results calculated by finite-difference time-domain and rigorous coupled-wave analysis methods presented that the nanogap enclosed by two neighboring nanogratings produced significant confinement and enhancement of electromagnetic fields and allowed a sensitive detection in sensing of surface binding events. Gold gratings with a narrow gap distance less than 10 nm showed enhanced refractive index sensitivity due to the intensified optical field at the nanogap, outperforming the LSPR structure with noninteracting nanogratings. Also, we analyzed the effectiveness of using an overlap integral (OI) between analyte and local plasmon field to estimate the detection sensitivity. We found a strong correlation of field–analyte OI with far-field sensor sensitivity.
© 2012 Optical Society of America
Optics at Surfaces
Original Manuscript: August 6, 2012
Revised Manuscript: September 25, 2012
Manuscript Accepted: September 26, 2012
Published: October 22, 2012
Rabiatul Adawiah Awang, Sherif Hamdy El-Gohary, Nak-Hyeon Kim, and Kyung Min Byun, "Enhancement of field–analyte interaction at metallic nanogap arrays for sensitive localized surface plasmon resonance detection," Appl. Opt. 51, 7437-7442 (2012)