Prospects for nanowire sculptured-thin-film devices

2013

Sci Rep

The commonly used optical sensor based on surface plasmon-polariton wave phenomenon can sense just one chemical, because only one SPP wave can be guided by the interface of a metal and a dielectric material contained in the sensor. Multiple analytes could be detected and/or the sensing reliability for a single analyte could be enhanced, if multiple SPP-wave modes could be excited on a single metal/dielectric interface. For that to happen, the partnering dielectric material must be periodically non-homogeneous. Using a chiral sculptured thin film (CSTF) as that material in a SPP-wave platform, we show that the angular locations of multiple SPP-wave modes shift when the void regions of the CSTF are infiltrated with a fluid. The sensitivities realized in the proof-of-concept experiments are comparable to state-of-research values.

mentioning

confidence: 99%

Optical sensing of analytes in aqueous solutions with a multiple surface-plasmon-polariton-wave platform

Swiontek

Pulsifer

2013

Sci Rep

“…Macroscopically, the optical properties of CTFs are equivalent to those of certain orthorhombic crystals. CTFs are attractive platforms for applications such as sensing chemical and biological species [11,12], due to the ability to engineer their macroscopic optical responses via control over the porosity and the columnar morphology at the fabrication stage.…”

mentioning

confidence: 99%

Polarization-state-dependent attenuation and amplification in a columnar thin film

Mackay

2017

J. Opt.

We numerically investigated the plane-wave reflection-transmission characteristics of a columnar thin film (CTF) whose columns are made from a dissipative material but whose void regions are filled with an active material. By computing the reflectances and transmittances, we found that the CTF can simultaneously amplify s-polarized incident light and attenuate p-polarized incident light, or vice versa. This polarization-state-dependent attenuation and amplification phenomenon depends upon the angle of incidence and the thickness of the CTF.

“…During every deposition, the angle of the collimated vapor flux with respect to the substrate plane was set at χ v = 20 deg. Furthermore, the substrate was rotated about the z axis in accordance with the M:1 asymmetric serial bi-deposition technique [28,33] as follows. A subdeposit was made for time τ , followed by a rapid rotation about the z axis by 180 deg in 0.406 s, followed by another subdeposit for time τ /M , followed by a rapid rotation about the z axis by 183 deg in 0.413 s. This 4-step process was iterated 120 times in order to deposit a single period.…”

Section: Fabrication Of Cstfsmentioning

confidence: 99%

Chiral sculptured thin films for circular polarization of mid-wavelength infrared light

Vepachedu

2018

Appl. Opt.

Being an assembly of identical upright helices, a chiral sculptured thin film (CSTF) exhibits the circular Bragg phenomenon and can therefore be used as a circular polarization filter in a spectral regime called the circular Bragg regime. This has been already demonstrated in the near-infrared and short-wavelength infrared regimes. If two CSTFs are fabricated in identical conditions to differ only in the helical pitch, and if both are made of a material whose bulk refractive index is constant in a wide enough spectral regime, then the center wavelengths of the circular Bragg regimes of the two CSTFs must be in the same ratio as their helical pitches by virtue of the scale invariance of the frequency-domain Maxwell postulates. This theoretical result was confirmed by measuring the linear transmittance spectra of two zinc-selenide CSTFs with helical pitches in the ratio 1:7.97. The center wavelengths were found to be in the ratio 1:7.1, and the deviation from the ratio of helical pitches is explainable at least in part because the bulk refractive index of zinc selenide decreases a little with wavelength. We concluded that CSTFs can be fabricated to function as circular polarization filters in the mid-wavelength infrared regime.