Use of Dispersion Imaging for Grating-Coupled Surface Plasmon Resonance Sensing of Multilayer Langmuir–Blodgett Films

Abstract

We report grating-coupled surface plasmon resonance measurements involving the use of dispersion images to interpret the optical response of a metal-coated grating. Optical transmission through a grating coated with a thin, gold film exhibits features characteristic of the excitation of surface plasmon resonance due to coupling with the nanostructured grating surface. Evidence of numerous surface plasmon modes associated with coupling at both front (gold/air) and back (gold/substrate) grating interfaces is observed. The influence of wavelength and angle of incidence on plasmon coupling can be readily characterized via dispersion images, and the associated image features can be indexed to matching conditions associated with several diffracted orders at both the front and back of the grating. These features collapse onto a set of global dispersion curves when plotted as peak energy versus the grating wavevector, with feature locations clustered according to the refractive index values of the neighboring dielectric material, either air or polycarbonate. Coating of the grating with multilayer arachidic acid films via Langmuir-Blodgett deposition results in red-shifting of some, but not all, of the plasmon features. The magnitude of the shift is a function of the film thickness, wavelength, and angle of incidence. Dispersion images clearly depict the red-shifting and also broadening of the front side features with increasing film thickness. In contrast, little change is observed in features associated with the back-side of the grating. The nature and magnitude of the interaction between the plasmon modes appearing at the front and back sides of the grating are discussed and analyzed in terms of the predicted interactions determined via optical modeling calculations.

Design and characterization of a plasmonic Doppler grating for azimuthal angle-resolved surface plasmon resonances

“…Equation (1) links the resonant wavelength to the grating periodicity and provides a simple guideline for the design of grating SP couplers. For such simplicity, plasmonic gratings have been widely used for index sensing 6,12 , color filtering [13][14][15] , surface enhanced spectroscopy [16][17][18] , hot electron generation 7 , color selective CMOS photodetector 8 , light tailoring and collimation 19 as well as logic gates in optical nanocircuits 20 . So far, most of the gratings are designed to have a constant periodicity and the performance is optimized at the resonant frequency.…”

Interactions between excitation and extraction modes in an organic-based plasmon-emitting diode

“…Most research in the recent decade have focused on increasing radiation efficiency [5][6][7], in which surface plasmon-coupled emission (SPCE) mechanisms from fluorescent molecules by incident wave excite an evanescent field near the Kretschmann configuration [8][9][10]. Recent efforts have implemented organic-based plasmonic emitting diodes by using the surface plasmon grating-coupled emissions (SPGCE) [11,12] to develop related design concepts and technologies for sensing applications [13][14][15][16][17]. This SPGCE brings internal dipole interaction and light extraction mechanisms on the metal nanostructures [18,19].…”

Exploration of grating-based surface plasmon resonance systems for wave vector matching to enhance plasmon modes and preliminary surface plasmon-enhanced fluorescence interrogation

“…This RI sensitivity allows for high throughput label free sensing/diagnostics [26][27][28][29][30][31] and thin film deposition tracking. [32][33][34][35][36][37][38][39][40] Additionally, because SPR peak shift can be tracked versus time, kinetics and binding affinity can be elucidated. 19,41,42 The first commercial SPR instrument for binding affinity was sold in 1990 under the name of BIACORE.…”

“…Surface plasmon resonance (SPR) is a powerful and highly versatile optical phenomena utilized for various analytical measurements such as label free sensing of adsorption, 99 measurement of binding affinities, 19,41,42 and monitoring thin film deposition. 32,35,38,39 These measurements exploit SPR's sensitivity to changes in surface optical properties, 25,90 namely deviations in near-field optical parameters such as refractive index. The enhanced surface electric field associated with SPR can also be used to enhance or amplify surface spectroscopies.…”

“…39,75 They also provide increased information density by plasmon excitation through multiple diffractive orders. 38,39,70,87,[139][140][141][142] Factors affecting the plasmonic response of nanostructured surfaces include the amplitude, shape and periodicity of the surface profile. 75,76,143 Degrees of grating symmetry also affect plasmonic responses, as 2D gratings excite surface plasmons (SPs) differently and can increase sensitivity.…”