Coupling between Surface Plasmon Modes of Single-Layer Complex Silver Nanohole Arrays and Enhancing Index Sensing

Abstract

By independently tuning the structure parameters of the nanorods in nanohole arrays (NRinNH), the localized surface plasmon resonance (LSPR)-induced extraordinary optical transmission (EOT) mode and the surface plasmon polariton (SPP)-induced EOT modes can be coupled to introduce a mode splitting phenomenon in a simple one-layer plasmonic nanostructure. We demonstrate that the coupling and energy exchange of the two different types of EOT modes of the NRinNH structure can simultaneously improve the near-field electromagnetic enhancement and spectral resolution of the LSPR-induced EOT peak, while they reduce the spectral resolution of the SPP-induced EOT modes. The hybrid modes of the NRinNH structure can be tuned to the NIR wavelength region by the length of the NR, of which the large resonance wavelength is highly preferred for improving the refractive index sensitivity (RIS) of the plasmonic sensor. In addition, using the difference in the polarization transmission spectra of NRinNH structures, the figure of merit (FOM) of the sensor performance can be significantly improved. The effect of coupling on different EOT modes in plasmonic sensing is systematically studied. A high RIS of 1200.6 nm/RIU and a high FOM of 279.2 RIU–1 are achieved. This provides guidance for the design of LSPR sensors based on complex NH structures with high FOM.

Plasmon Hybridizations in Compound Nanorod–Nanohole Arrays

“…Based on our recent experimental and numerical calculation for tilted Ag nanorods on Ag NH arrays, the appearance of the additional λ 0 transmission peak in the 1RNH structure is due to a dipole-oscillation-induced enhanced transmission from the nanorods [ 17 , 18 , 19 , 20 , 24 ]. Similar understanding can be applied to the 1RNH.…”

“…Thin AAAs can shift the resonant wavelength of EOT, create high electric fields in the nanodisk-nanohole gaps [ 8 , 9 , 10 ], improve the performance of EOT-based sensors [ 11 , 12 , 13 ], serve as substrates for surface-enhanced infrared absorption spectroscopy [ 14 ] and surface-enhanced Raman scattering [ 15 ], and even be utilized for constructing waveplates [ 16 ], etc. Additionally, nanorod-in-nanohole (NR-in-NH) structures have been extensively investigated both theoretically [ 17 , 18 , 19 ] and experimentally [ 20 , 21 ]. It has been observed that multiple parameters, such as hole diameter, rod length and aspect ratio, rod position, and the period of the nanohole array, can be simultaneously tuned to control the plasmonic properties, enabling multiple instances of coupling between SPPs and LSPs.…”

Recent Advances in Silver Nanostructured Substrates for Plasmonic Sensors

“…The variations in the plasmonic resonant shift with respect to the aspect ratio of the AgNRs and film thickness were studied [ 98 , 99 ]. Ag nanostructured grating substrates show significant plasmonic enhancement and, therefore, have been exploited for surface plasmon-based refractive index sensors [ 100 , 101 ] and SERS-based sensors [ 102 , 103 ].…”

Plasma amplifiers: multiscale light-enhanced uniform SERS composite substrates for breaking through resonance limitations

“…[1][2][3][4][5] To enhance Raman signals, nanostructured noble metal materials have gained immense popularity owing to their unique plasmonic properties. [6][7][8][9][10] Through nanoscale modulation of plasmons, surface-enhanced Raman spectroscopy (SERS) can easily enhance the Raman signal by more than six orders of magnitude. [11][12][13][14][15] However, traditional noble metal nanoparticles (NPs) have their limitations, encompassing restricted signal enhancement, uneven distribution of hotspots, and poor reproducibility.…”