Comprehensive analysis of photonic nanojets in 3D dielectric cuboids excited by surface plasmons

Abstract

In this paper we study the excitation of photonic nanojets (PNJ) in 3D dielectric cuboids by surface plasmons at telecommunication wavelengths. The analysis is done using the effective refractive index approach. It is shown that the refractive index contrast between the regions with and without cuboid should be roughly less than 2 in order to generate jets at the output of the cuboid. The best performance at λ 0 = 1550 nm is obtained when the height of the cuboid is 160 nm producing a jet just at the output interface with a subwavelength resolution of 0.68λ 0 and a high intensity enhancement (×5) at the focus. The multi-wavelength response is also studied demonstrating that it is possible to use the proposed structure at different wavelengths. Finally, the backscattering enhancement is numerically evaluated by inserting a metal particle within the PNJ region, demonstrating a maximum value of ß2.44 dB for a gold sphere of radius 0.1λ 0 .

Photonic Hook Plasmons: A New Curved Surface Wave

“…As in refs. [], a non‐uniform mesh with a maximum cell size of 1/5λ 0 at the dielectric‐metal interface was applied. All the field distributions shown below are normalized by their maximum values.…”

“…Moreover, the SPP PJ is moved away from the cuboid as it is enlarged. It was also demonstrated that it is possible to detect subwavelength (0.1 λ) metal particles by means of plasmonic PJ . Lately, it was shown that the SPP PJ performance can be engineered by simply changing the height of the dielectric at the operation wavelength for the flat disk, cuboid, and also with the plasmonic lenses …”

“…Second, as it was mentioned above, since the SPPs have a very short propagation distance due to the large Ohmic loss, the resulting beams should be formed directly in the near‐field, before they decay . Moreover, SPPs are excited over a finite propagation distance and therefore their phase cannot be simply defined at a specific 1D plane . Also, it is possible to increase the propagation length of the SPP waves using, for example, cascaded dielectric particles or metamaterials …”

“…This process is fundamentally simpler than the generation of the SPP Airy‐family beams . The formation of the PH in a free‐space and in a symmetrically flat cuboid particle in SPP has been previously investigated. The influence of the size and dielectric flat prism angle of an asymmetric particle on the distribution of SPP field enhancement, the full‐width at half‐maximum (FWHM), and curvature of PHP is effectively quantified here.…”

Specialized directional beaming through a metalens and a typical application

“…Extra ordinary enhanced transmission through subwavelength metallic structures such as slits and holes have been reported by numerous researchers in the last decade [2][3][4][5][6][7][8][9][10][11][12][13][14][15]. One of the typical works is the presentation regard ing the control of beaming through the subwavelength metallic slits reported by Yu et al in Ref.…”