Since the first application of the surface plasmon resonance (SPR) phenomenon for sensing almost two decades ago, this method has made great strides both in terms of instrumentation development and applications. SPR sensor technology has been commercialized and SPR biosensors have become a central tool for characterizing and quantifying biomolecular interactions. This paper attempts to review the major developments in SPR technology. Main application areas are outlined and examples of applications of SPR sensor technology are presented. Future prospects of SPR sensor technology are discussed.

Surface plasmon resonance sensors: review

Nano-optics of surface plasmon polaritons

In this review we look at the concepts and state-of-the-art concerning the strong coupling of surface plasmon-polariton modes to states associated with quantum emitters such as excitons in J-aggregates, dye molecules and quantum dots. We explore the phenomenon of strong coupling with reference to a number of examples involving electromagnetic fields and matter. We then provide a concise description of the relevant background physics of surface plasmon polaritons. An extensive overview of the historical background and a detailed discussion of more recent relevant experimental advances concerning strong coupling between surface plasmon polaritons and quantum emitters is then presented. Three conceptual frameworks are then discussed and compared in depth: classical, semi-classical and fully quantum mechanical; these theoretical frameworks will have relevance to strong coupling beyond that involving surface plasmon polaritons. We conclude our review with a perspective on the future of this rapidly emerging field, one we are sure will grow to encompass more intriguing physics and will develop in scope to be of relevance to other areas of science.

https://iopscience.iop.org/article/10.1088/0034-4885/78/1/013901/pdf

Strong coupling between surface plasmon polaritons and emitters: a review

Tethered polymer chains refers to macromolecular chains that are attached into microstructures by their ends. Highly branched polymers, polymer micelles and end-grafted chains on surfaces are a few examples. This review brings out the common features of these seemingly widely disparate microstructures. Tethering can be reversible or irreversible and is frequently sufficiently dense that the chains are crowded. Densely tethered chains stretch to alleviate the interactions caused by crowding. They thus exhibit deformed configurations at equilibrium. These effects of tethering on the structure of the polymer chains are reflected in distinctive behavior and properties of microstructures containing tethered chains.

Tethered chains in polymer microstructures

Characterization of organosulfur molecular monolayers on au(111) using scanning tunneling microscopy

Fourier transform IR measurements of Langmuir–Blodgett monolayers have been made with both grazing incidence reflection and transmission techniques. The reflection arrangement at incident angles from 85° to 88° has the electric field component perpendicular to the substrate surface while the standard transmission arrangement has the electric field component in the plane of the film. These techniques were used to explore the anisotropic arrangement of cadmium arachidate molecules perpendicular and parallel to the monolayer plane. The implication of these results for characterizing the orientational anisotropy of chemical groups in thin polymer films is also discussed. In addition, the question of uniaxial and biaxial orientation in the monolayer plane was addressed because of the importance of intermolecular packing on both the extent and rate of polymerization in unsaturated fatty acid monolayer components which form synthetic membranes.

Anisotropic orientation in molecular monolayers by infrared spectroscopy

Surface plasmon spectroscopy of organic monolayer assemblies

Real-time monitoring of the corona-poling process that is used to create a bulk second-order nonlinear-optical susceptibility was accomplished by observing electrochromic shifts and intensity decreases of charge-transfer absorption bands in both dye-doped and covalently functionalized polymer films. By measuring small changes in the refractive-index anisotropy, the optical waveguiding technique was demonstrated to be a sensitive measure of the poling-induced order and its relaxation. The guest–host systems were formed from the dyes N,N-dimethylaminonitrostilbene, N,N-dimethylindoaniline (Phenol Blue), and 4-(N-(2-hydroxyethyl)-N-ethyl)-amino-4′-nitroazobenzene (Disperse Red 1), each dissolved in a poly(methyl methacrylate) matrix. The covalently functionalized polymers contained pendant para-nitroaniline (PNA) moieties. The first, poly(N-(4-nitrophenyl)allylamine), was formed from a poly(allylamine) derivative and is called PPNA. The second was based on poly(hydroxystyrene), with PNA attachment occurring between the phenol group and the PNA hydroxyethyl group; this polymer is named PHS-MENA. The final polymer is a linear epoxy (bisphenol A) with the PNA amino N atoms forming a link in the main chain; it is called Bis A-NA. A sample calculation demonstrated the use of experimental electrochromic spectral data to estimate the electro-optic coefficients.

Electrochromic and optical waveguide studies of corona-poled electro-optic polymer films

Thin films for optical second‐harmonic generation (SHG) were prepared from a newly designed and synthesized amorphous polymer that incorporated a high density of active nonlinear optical groups (p‐nitroaniline as attached side groups). For alignment of the nonlinear groups a very high electric field was applied by a corona discharge to the polymer films above Tg (125 °C). The subsequent freezing process resulted in a polymer film initially exhibiting a very high second‐order nonlinear coefficient, d33=31 pm/V, measured by the Maker‐fringe technique, plus excellent thermal, mechanical, and optical properties. The dynamics of polar alignment and decay, studied by in situ poling (or depoling) and SHG measurements, indicated a multiple exponential behavior with the average relaxation time somewhat longer than expected from extrapolation of the dielectric relaxations data according to the Williams–Landel–Ferry equation. The frozen‐in SHG behavior at room temperature (∼100 °C below Tg) relaxed after 5 days to a...

Corona poling and real‐time second‐harmonic generation study of a novel covalently functionalized amorphous nonlinear optical polymer

Extending the novel method of Eich et al. [J. Appl. Phys. 66, 3241 (1989)] to prepare highly stable second‐order nonlinear optical (NLO) polymers via chemical cross‐linking under electric field, we have obtained a new polymer exhibiting large and stable second‐order optical nonlinearities after relaxation at 80 °C. This was achieved by forming a network polymer from two NLO‐active monomers, bifunctional N,N‐(diglycidyl)‐4‐nitroaniline and trifunctional N‐(2‐aminophenyl)‐4‐nitroaniline. Here, every NLO moiety is connected to the network by a single covalent bond. After full cure under corona poling at 120 °C, the sample exhibited at ambient conditions d33≂50 pm/V and d31≂16 pm/V at 1064 nm fundamental wavelength, as estimated from the Maker fringe data. Upon heating to 80 °C, the nonlinearities decreased somewhat initially, but leveled off and remained stable at 80 °C. This stable sample gave d33≂42 pm/V and d31≂14 pm/V at ambient conditions. Furthermore, the linear electro‐optical coefficient of this samp...

Jerome D. Swalen

Papers

Anisotropic orientation in molecular monolayers by infrared spectroscopy

Surface plasmon spectroscopy of organic monolayer assemblies

Electrochromic and optical waveguide studies of corona-poled electro-optic polymer films

Corona poling and real‐time second‐harmonic generation study of a novel covalently functionalized amorphous nonlinear optical polymer

Highly efficient and stable nonlinear optical polymers via chemical cross‐linking under electric field