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Why FETs detect a THz signal at a frequency far beyond their amplifying capabilities

Marczewski Jacek, Zaborowski Michał, Tomaszewski Daniel, Zagrajek Przemysław, Pałka Norbert

Opto-Electronics Review

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2024

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Vol. 32, No. 4

art. no. e151989

EN

Field-effect transistors (FETs) are efficient detectors of THz radiation. Despite over three decades of research, controversy still exists regarding the detection mechanism. The article attempts to solve this problem systemically. Existing approaches to modeling THz detection are critically reviewed, including plasmonic, resistive mixing, hot carrier and thermal models. Limitations and inconsistencies of the first two approaches, along with some classical physics principles and experiments conducted, were identified. These include the facts that some models were formulated independently of material relaxation time constraints, and the plasmonic approach does not take into account the conditions for the formation of surface plasmon-polarons and does not describe the case of p-type devices (hole plasmons have never been experimentally recorded). Relevant measurements and theoretical considerations illustrate the inadequacy of these models. As a result of this analysis, thermoelectric models are expected to explain THz sensing by FETs.

2

Linear and nonlinear ΤM polarized surface waves in anisotropic metamaterials

Ali Munazza Zulfiqar

Optica Applicata

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2019

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Vol. 49, nr 3

473--486

EN

The metamaterial with an effective permeability and/or permittivity tensor having elements of different magnitudes and signs is termed as the anisotropic metamaterial. The hyperbolic metamaterial may be considered as a subclass of the anisotropic metamaterial. The dispersion relation for the transverse magnetic surface waves at the interface between a nonlinear dielectric material and an anisotropic metamaterial is derived using the parallel uniaxial approximation of the permittivity tensor. This dispersion relations can be linearized by taking the nonlinear coefficient to be zero. Dispersion curves are plotted for both the linear and the nonlinear cases and are analyzed and compared in different frequency regions.

3

D-shape polymer optical fibres for surface plasmon resonance sensing

Gasior K., Martynkien T., Wojcik G, Mergo P., Urbanczyk W.

Opto-Electronics Review

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2017

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Vol. 25, No. 1

1--5

EN

We experimentally studied three different D-shape polymer optical fibres with an exposed core for their applications as surface plasmon resonance sensors. The first one was a conventional D-shape fibre with no microstructure while in two others the fibre core was surrounded by two rings of air holes. In one of the microstructured fibres we introduced special absorbing inclusions placed outside the microstructure to attenuate leaky modes. We compared the performance of the surface plasmon resonance sensors based on the three fibres. We showed that the fibre bending enhances the resonance in all investigated fibres. The measured sensitivity of about 610 nm/RIU for the refractive index of glycerol solution around 1.350 is similar in all fabricated sensors. However, the spectral width of the resonance curve is significantly lower for the fibre with inclusions suppressing the leaky modes.

4

D-shape polymer optical fibres for surface plasmon resonance sensing

Gasior K., Martynkien T., Wojcik G., Mergo P., Urbanczyk W.

Opto-Electronics Review

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2016

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Vol. 24, No. 4

209--215

EN

We experimentally studied three different D-shape polymer optical fibres with an exposed core for their applications as surface plasmon resonance sensors. The first one was a conventional D-shape fibre with no microstructure while in two others the fibre core was surrounded by two rings of air holes. In one of the microstructured fibres we introduced special absorbing inclusions placed out side the microstructure to attenuate leaky modes. We compared the performance of the surface plasmon resonance sensors based on the three fibres. We showed that the fibre bending enhances the resonance in all investigated fibres. The measured sensitivity of about 610 nm/RIU for the refractive index of glycerol solution around 1.350 is similar in all fabricated sensors. However, the spectral width of the resonance curve is significantly lower for the fibre with inclusions suppressing the leaky modes.

5

Compositional arrangement of rod/shell nanoparticles: an approach to provide efficient plasmon waveguides

Ahmadivand A., Golmohammadi S.

Opto-Electronics Review

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2014

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Vol. 22, No. 2

101-108

EN

In this work, we investigated the optical properties of a novel compositional configuration of gold nanorod and silver nanoshell which is embedded in a SiO₂ substance. The proper geometrical sizes for compositional rod/shell arrangement have been obtained based on the position and peak of plasmon resonance at λ~1550 nm. Adjusting the plasmon resonance position at declared spectrum helps us to provide an arrangement which shows high efficiency and minimum losses. The influence of destructive components such as internal damping and scattering on the rod/shell combination is demonstrated by corresponding diagrams. Moreover, we proposed a nano-array based on examined configuration and the quality of light transmission along the array is studied. We figured out and depicted optical properties of the array such as transmission loss factors, group velocities, transmitted power, transmission quality, and two-dimensional snapshots of surface plasmons (Sps) coupling between nanoparticles arrangements under transverse and longitudinal modes excitations. Ultimately, it is shown that the suggested nanostructure based on studied nanoparticles configuration has a potential to utilize in designing nanophotonic devices such as splitters, couplers, and routers. Finite-difference time-domain method (FDTD) as a major simulation model has been employed to study the features of the waveguide.

6

Plasmon polaritons in metal nanostructures : the optoelectronic route to nanotechnology

Salerno M., Krenn R. R., Lamprecht B., Schider G., Ditlbacher H., Felidj N., Leitner A., Aussenegg F. R.

Opto-Electronics Review

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2002

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Vol. 10, No. 3

217-224

EN

In the light of recent advances in subwavelength optics, the development of optical nanodevices is nowadays conceivable. Among the best candidates to act as the elementary components of such devices are nanoscale structures of noble metals. These materials are capable to sustain resonant electron oscillations (plasmons). This phenomenon gives rise to a spectrally selective optical response and a local field enhancement which can be used in the context of nano-optics. Furthermore, it allows to transduce the optical signals into electrical ones (and vice wersa). Here, we demonstrate an optical nanodevice based on plasmon resonances in gold nanostructures. The adequate metal structures were produced by electron-beam-lithography. The basic operating functions of the device, namely signal processing on the nanoscale and its interfacing on the microscale, were experimentally observed in the optical near-field by photon scanning tunneling microscopy. Furthermore, as a numerical method for validation of the near-field observations the Green's Dyadic Technique is pointed out.