Plasmonic sensors based on thick metal film perforated with rectangular nanohole arrays

Abstract

The dependence of optical properties on the ambient medium, the period of nanohole arrays and the metal film thickness in a thick silver film perforated with rectangular nanohole arrays is investigated using the finite‐difference time‐domain technique. As a result of the coupling between top and down surface plasmon polaritons, mediated by localized surface plasmon resonances supported by the metallic rectangular nano‐ holes, interesting light phenomena are observed for varying thickness of the metal film and period of the rectangular nanohole arrays. Based on the dependence of the optical properties on the ambient medium, the possibility of exploiting thick metal rectangular nanohole arrays as plasmonic sensors is further discussed, the potential application as plasmonic sensors is revealed. (© 2013 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Coupling effects in bilayer thick metal films perforated with rectangular nanohole arrays

“…Figure 5(a)-5(c) show the electric-field distribution at the resonant wavelength of 445 nm in one layer of the bilayer silver rectangular nanohole arrays: Figure 5(a) for cross section through the center of the layer, with the direction of electric-field perpendicular to the cross section; Figure 5(b) and 5(c) for cross sections near the top and bottom plane of the layer respectively, with the direction of electric-field parallel to x-axis. As can be seen from Figure 5(a)-5(c) that the electric-field distribution in one layer of the bilayer silver rectangular nanohole arrays presents similar behaviors as that in monolayer silver rectangular nanohole arrays, which were revealed by our previous works: 18,19 Figure 5(a) show that the electric-field is mainly focusing near the two longer sides of the rectangular hole, and the electric-field distribution presents antisymmetric coupling between the electric-field near the two long sides of rectangular hole; Figure 5 top and bottom plane of the metal nanohole arrays, away from the sides of the hole in the metal film. From the electric-field distribution in the structure, it can be deduced that two types of antisymmetric coupling of surface plasmon resonances probably be excited in thick metal film perforated with rectangular nanohole arrays: the antisymmetric coupling between surface plasmon polaritons near the top and bottom film plane, and the antisymmetric coupling between localized surface plasmon resonances near the two long sides of the rectangular hole; the antisymmetric coupling of localized surface plasmon resonances near the two long sides of the rectangular hole would probably help the stimulation of the antisymmetric coupling between surface plasmon polaritons near the top and bottom film plane.…”

“…Our above deductions are certified by the investigation of the electric-field distribution and electrical current-density distribution in metal nanohole arrays, which are present in our previous work. 18,19 When the thickness of the metal film decreases continually, the two transmission coefficient peaks would be far away from each other with they blueshifting and redshifting respectively, while the strength of the transmission coefficient peak at short wavelength becomes weaker and weaker, and the strength of the transmission coefficient peak at long wavelength becomes stronger and stronger. The antisymmetric coupling mode between the top and down surface plasmon polaritons has very important potential application, such as plasmonic sensors and optical magnetic metamaterials.…”

“…The antisymmetric coupling mode between the top and down surface plasmon polaritons has very important potential application, such as plasmonic sensors and optical magnetic metamaterials. 18,19,[23][24][25] As the antisymmetric coupling mode between the top and the bottom surface plasmon (corresponding to transmission coefficient peak at short wavelength) can be excited efficiently in the monolayer metal rectangle nanohole arrays with the thickness of 120 nm, the optical properties for the exemplary system of bilayer silver rectangular nanohole arrays with the same thickness of 120 nm (the longer side and short side of the rectangular nanohole are 100 nm and 20 nm respectively; the periods of nanohole arrays with the square lattice are 150 nm.) are investigated and the results will be present as follows.…”

“…[13][14][15][16][17] Previous researches were mainly focused on thin metal films perforated with subwavelength hole arrays in the framework of extraordinary optical transmission, while our previous work revealed that many interesting light phenomena were observed in thick metal films perforated with nanohole arrays, and especially there are many important potential applications based on thick metal films perforated with rectangular nanohole arrays. 18,19 There is probably hybridization of localized surface plasmon resonances modes supported by metallic nanoholes, when neighboring metallic nanoholes interact, and the hybridization is mediated by the nearby metallic surface plasmon polaritons which gives marked differences in optical response compare to metallic nanoparticles; at the same time, there are probably symmetric coupling mode and antisymmetric coupling mode between the top and down surface plasmon polaritons, mediated by those localized surface plasmon resonances modes, so a much richer range of optical phenomena probably present. In this paper, the coupling effects in bilayer thick metal (silver) films perforated with rectangular nanohole arrays are investigated using the finite-difference time-domain technique.…”

Electrolytic deposition of TiC nanoparticles/Ag composite films and their optical properties

“…With regard to its potential applications, optically thick metal film perforated with subwavelength hole arrays was found to have many potential applications in the field of plasmonic sensors, metamaterials, photonic devices and so on [17][18][19][20][21], but related research is still in its infancy due to technical obstacles. In order to fabricate subwavelength elements, nanoimprint lithography [22], e-beam lithography [23], focused-ion beam writing [24] or more advanced and expensive lithography techniques based on multi-photon polymerisation [25][26][27] are usually introduced.…”