Actuated plasmonic nanohole arrays for sensing and optical spectroscopy applications

Abstract

Herein, we report a new approach to rapidly actuate the plasmonic characteristics of thin gold films perforated with nanohole arrays that are coupled with arrays of gold nanoparticles. The near-field interaction between the localized and propagating surface plasmon modes supported by the structure was actively modulated by changing the distance between the nanoholes and nanoparticles and varying the refractive index symmetry of the structure. This approach was applied by using a thin responsive hydrogel cushion, which swelled and collapsed by a temperature stimulus. The detailed experimental study of the changes and interplay of localized and propagating surface plasmons was complemented by numerical simulations.We demonstrate that the interrogation and excitation of the optical resonance to these modes allow the label-free SPR observation of the binding of biomolecules, and is applicable for in situ SERS studies of low molecular weight molecules attached in the gap between the nanoholes and nanoparticles. † Electronic supplementary information (ESI) available. See

Self-Assembled Metal Nanohole Arrays with Tunable Plasmonic Properties for SERS Single-Molecule Detection

“…Supporting localized surface plasmons (LSPs), propagating surface plasmons (also referred to as surface plasmon polaritons SPPs) resonances as well as diffractive optical modes due to their periodic arrangement, metal nano-hole arrays are the most versatile plasmonic nanostructures. It is possible to modulate the intensity and the spectral position of these modes across the visible to near-infrared range by changing the periodicity, size of the hole, and metal composition, making them the proper choice both for refractive index sensing and surface-enhanced spectroscopies applications [ 13 , 14 , 15 ]. The interaction between the involved modes can also be properly engineered for a fine-tuning of electromagnetic field distribution and confinement on the metal surface or inside the holes.…”

Materials design of vertically coupled plasmonic arrays

“…The plasmon resonance position is extremely sensitive to the dielectric environment of plasmonic nanostructure. [12][13][14] This property is extensively used in surface plasmon resonance spectroscopy to detect binding events of biological macromolecules at the plasmonic template. 14 Therefore, the refractive index of the substrate and the pillars is important.…”

“…8 For small nanopillar aspect ratios the plasmon resonance of (i) the disk array, and (ii) the hole lm can hybridize and couple vertically. The optical response of such vertically coupled plasmonic arrays (VCPAs) exhibits extraordinary optical transmission, which has been exploited to fabricate optical lters, [9][10][11] refractive index sensors [12][13][14] or plasmonic nanopixels beyond the diffraction limit. [15][16][17] Further, small plasmonic junctions between the two plasmonic slabs of the VCPAs can drastically increase the local electric near-eld.…”

“…Such simulations are routinely used to predict and verify the optical behavior of experimentally fabricated plasmonic metasurfaces. [1][2][3][4][5][6][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23] Finally, we demonstrate that VCPAs can effectively form plasmonic heterostructures commonly used in plasmon-enhanced photocatalysis.…”

Shape Modulation of Plasmonic Nanostructures by Unconventional Lithographic Technique

“…Controllable nanometer-scale engineering of plasmonic resonance and EM field localization is a key factor in the realization of new functionalities or for enhancing surface-dependent optical phenomena [ 45 , 46 , 47 , 48 , 49 ]. Proper engineering of localized electric fields on the metal surface [ 44 , 50 ], can be exploited in different technological ambits: optical filters [ 51 , 52 ], the amplification of weak spectroscopy signals such as fluorescence [ 53 , 54 ] and Raman scattering [ 2 , 55 , 56 ], second-harmonic generation [ 57 ], and particularly molecular sensing [ 58 ].…”