Coupling efficiency of light to surface plasmon polariton for single subwavelength holes in a gold film

Abstract

The excitation of surface plasmon polaritons (SPP) by focusing a laser beam on single subwavelength holes opened in a thin gold film is studied both experimentally and theoretically. By means of leakage radiation microscopy, quantitative measurements of the light-SPP coupling efficiency are performed for holes with different sizes and shapes. The system is studied theoretically by using a modal expansion method to calculate the fraction of the incident energy which is scattered by the hole into a surface plasmon. We demonstrate that a single subwavelength hole can be used to generate SPP with an efficiency up to 28%.

Efficiency of local surface plasmon polariton excitation on ridges

“…15 The efficiency of light-SPP coupling, defined as the ratio of SPP power to that of light, for some configurations has been evaluated both experimentally and numerically. 9,10,[15][16][17] The efficiency of the techniques that use radially polarized Bessel or highly focused parallel beams can be quite high. 9,10 But apart from the already mentioned disadvantage of use of thin metal films, those methods, especially the former one, produce SPPs with virtually all directions of their k vectors.…”

“…This is already a very good result if one bears in mind that it is a local coupling configuration, and such commercial devices in serial production could be virtually fabricated on a microchip. A very recent study of light coupling to SPP for a single subwavelength hole in a gold film 16 revealed the efficiency of up to 28%. Note, though, that this is the value normalized with respect to the power incident onto the hole area, meaning that the absolute efficiency ͑normalized with respect to the total incident power͒ is considerably smaller.…”

Localized surface-plasmon resonances in periodic nondiffracting metallic nanoparticle and nanohole arrays

“…16 Since then it has been demonstrated that under appropriate conditions single nanoholes in metallic films may support LSPRs in a manner analogous to that of nanoparticles. [17][18][19][20][21][22] The similarities between the LSPRs of nanoholes and nanodiscs were discussed by Haynes et al 10 Indeed, Käll and co-workers 17 recently showed that for irregular arrays of such holes the LSPRs of the nanoholes are blueshifted as the hole density is increased, an effect attributed to coupling between LSPRs of neighboring holes. However, as far as we are aware, there has not yet been a comparison of interparticle/interhole coupling in periodic nondiffracting metallic nanoparticle/nanohole arrays.…”

Plasmas meet plasmonics

“…However, controlling (or even predicting) where hot spots will occur is very challenging. This means particular attention (and thorough modelling efforts) need to be directed at understanding and finding fabrication methods capable of controlling the coupling between plasmonic nanostructures with various sizes, shapes, composition, spacing and orientations [91,[97][98][99][100][101][102][103][104][105][106][107]. The tailoring of NP size, shapes and array properties such as ordering, regularity etc.…”