Abstract

In this work, for the first time, a study was conducted of the existence of Extraordinary Optical Transmission (EOT) in Silicon (Si) thin films with subwavelength holes array and high excess carrier concentration. Typically EOT is studied in opaque perforated metal films. Using Si would bring EOT and its many applications to the silicon photonics realm and the mid-IR range. Since Si thin film is a semi-transparent film in mid-IR, a generalization was proposed of the normalized transmission metric used in literature for EOT studies in opaque films. The plasma dispersion effect was introduced into the studied perforated Si film through either doping or carriers’ generation. Careful consideration for the differences in optical response modeling in both cases was given. Full-wave simulation and analysis showed an enhanced transmission when using Si with excess carriers, mimicking the enhancement reported in perforated metallic films. EOT was found in the mid-IR instead of the visible range which is the case in metallic films. The case of Si with generated excess carriers showed a mid-IR EOT peak reaching 157% around 6.68 µm, while the phosphorus-doped Si case showed a transmission enhancement of 152% around 8.6 µm. The effect of varying the holes’ dimensions and generated carriers’ concentration on the transmission was studied. The analogy of the relation between the fundamental mode cutoff and the EOT peak wavelength in the case of Si to the case of metal such as silver was studied and verified. The perforated Si thin film transmission sensitivity for a change in the refractive index of the holes and surroundings material was investigated. Also, a study of the device potential in sensing the hole and surroundings materials that have almost the same refractive index yet with different absorption fingerprints was performed as well.

Highlights

  • In this work, for the first time, a study was conducted of the existence of Extraordinary Optical Transmission (EOT) in Silicon (Si) thin films with subwavelength holes array and high excess carrier concentration

  • Gordon et al demonstrated through numerical simulation that, for metal films, enhanced transmission happens near the cutoff wavelength of the fundamental mode of the waveguide formed by a single rectangular hole

  • To enable studying EOT in perforated Si thin films, we introduce a generalization of the normalized-to-area transmission metric, typically used in literature to show EOT in perforated opaque metallic thin films [1,3,7,9,12]

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Summary

OPEN Extraordinary optical transmission in silicon nanoholes

For the first time, a study was conducted of the existence of Extraordinary Optical Transmission (EOT) in Silicon (Si) thin films with subwavelength holes array and high excess carrier concentration. Extraordinary Optical Transmission (EOT), discovered while studying light transmission through metal thin films with subwavelength holes array, was among the phenomena receiving much research since its discovery in 1998 1. To investigate the capability of using EOT in Si-based perforated films for sensing, a study of the EOT sensitivity for a refractive index change in the hole and surroundings material was performed. The second section in this article describes the structure design and simulation method It discusses the differences in material dispersion between doped Si and Si with generated excess carriers. The third section shows the results and discussion and the conclusions are given in the fourth section

Structure design and material dispersion
Results and discussion
Ahole Acell
PT Pi
Conclusions
Author contributions
Additional information
Full Text
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