Electromagnetic Characterization of Chiral Media

Margineda, J.; Molina‐Cuberos, G. J.; Nunez, M.J.; Garcia-Collado, A.J.; Martin, E.

doi:10.5772/51539

Cited by 13 publications

(18 citation statements)

References 33 publications

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“…where the subscripts R and L refer to RCP and LCP, respectively, concerning the circularly polarized waves, and x and y refer to linearly polarized waves along the two orthogonal directions. Moreover, TCD is calculated by using the following equation [10,44] TCD = 1 2 tan −1…”

Section: Resultsmentioning

confidence: 99%

“…[ 25,42,43 ] The transmittance coefficient for circular polarization was obtained from linear measurements and using the following equation

\begin{eqnarray}\left( { \def\eqcellsep{&}\begin{array}{@{}*{1}{c}@{}} {{T}_R}\\ {{T}_L} \end{array} } \right) = \dfrac{1}{2}\left( { \def\eqcellsep{&}\begin{array}{@{}*{1}{c}@{}} {({T}_{xx} + {T}_{yy}) + i({T}_{xy} - {T}_{yx})}\\[3pt] {({T}_{xx} + {T}_{yy}) - i({T}_{xy} - {T}_{yx})} \end{array} } \right)\end{eqnarray}

where the subscripts R and L refer to RCP and LCP, respectively, concerning the circularly polarized waves, and x and y refer to linearly polarized waves along the two orthogonal directions. Moreover, TCD is calculated by using the following equation [ 10,44 ]

\begin{equation} {\mathrm{TCD}=\frac{1}{2}{\tan}^{-1}\left(\frac{{\left|{T}_{R}\right|}^{2}-{\left|{T}_{L}\right|}^{2}}{{\left|{T}_{R}\right|}^{2}+{\left|{T}_{L}\right|}^{2}}\right)} \end{equation}

…”

Section: Resultsmentioning

confidence: 99%

See 1 more Smart Citation

Lithography‐Free Fabrication of Terahertz Chiral Metamaterials and Their Chirality Enhancement for Enantiomer Sensing

Hwang

Baek

et al. 2023

Advanced Optical Materials

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Chiral metamaterials comprise a promising platform for advanced optoelectronic and biomedical applications. However, conventional fabrication via lithography is limited by its complexity and high cost. Herein, the lithography-free fabrication of terahertz chiral metamaterials and their enhancement for sensing the chirality of biocrystal enantiomers is presented. Chiral Au microstrip patterns (CHAMs) in a saw-tooth shape are fabricated by combining two-step buckling processes and glancing-angle deposition. Non-superimposable geometric chirality is achieved by controlling the tilt angle between the asymmetric and biaxial strain axes and the selective area deposition of the Au layers by using the shadow effect. The manufactured chiral metamaterials show mirror-shaped terahertz circular dichroism (TCD) signals in the range of 0.2-2.5 THz. Coupling of the induced electric and magnetic dipoles to the chiral-shaped Au surfaces results in effective optical chirality enhancement. Finite-difference time-domain computational simulations reveal the homogeneous distribution of optical chirality with an absolute maximum of 2.24 in the near field. Summing the TCD signals for enantiomeric cystine biocrystals onto the chiral metamaterials shows an ≈7-fold amplification in magnitude. This enhancement can be attributed to the synergistic effects of superchiral field enhancement and the electromagnetic resonance between the CHAMs and biocrystals.

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Section: Resultsmentioning

confidence: 99%

“…[ 25,42,43 ] The transmittance coefficient for circular polarization was obtained from linear measurements and using the following equation

\begin{eqnarray}\left( { \def\eqcellsep{&}\begin{array}{@{}*{1}{c}@{}} {{T}_R}\\ {{T}_L} \end{array} } \right) = \dfrac{1}{2}\left( { \def\eqcellsep{&}\begin{array}{@{}*{1}{c}@{}} {({T}_{xx} + {T}_{yy}) + i({T}_{xy} - {T}_{yx})}\\[3pt] {({T}_{xx} + {T}_{yy}) - i({T}_{xy} - {T}_{yx})} \end{array} } \right)\end{eqnarray}

\begin{equation} {\mathrm{TCD}=\frac{1}{2}{\tan}^{-1}\left(\frac{{\left|{T}_{R}\right|}^{2}-{\left|{T}_{L}\right|}^{2}}{{\left|{T}_{R}\right|}^{2}+{\left|{T}_{L}\right|}^{2}}\right)} \end{equation}

…”

Section: Resultsmentioning

confidence: 99%

Lithography‐Free Fabrication of Terahertz Chiral Metamaterials and Their Chirality Enhancement for Enantiomer Sensing

Hwang

Baek

et al. 2023

Advanced Optical Materials

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“…The usual LP waves method makes use of R xx , T xx and T xy and define the parameter T 2 = T 2 xx + T 2 yx in order to calculate ǫ r and µ r [5]. Here we propose to calculate T 2 using the transmission coefficients for both CP and LP waves:…”

Section: Methods and Discussionmentioning

confidence: 99%

“…The presence of the chirality parameter in the constitutive equations do necessary to measure, at least, three independent quantities in order to retrieve ǫ r , µ r and κ [4]. The standard free-wave setup consists of a pair of transmitting and receiving antennas to determine both the reflection coefficient and the co-and cross-polar components of the transmission coefficients when the slab sample is irradiated with LP waves [5]. The inherent errors associated to the measurements and the strong variations in the constitutive parameters make, in some cases, quite complicated to retrieve the constitutive parameters.…”

Section: Introductionmentioning

confidence: 99%

Chiral media characterization using both linear and circular polarized waves

Molina‐Cuberos

Nunez

Margineda

et al. 2017

2017 IEEE International Symposium on Antennas and Propagation &Amp; USNC/URSI National Radio Science Meeting

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A new free-wave experimental method for chiral media characterization is presented. The setup is based on a pair of dual horn antennas and a diplexer 90 • phase shifter, which allows to produce both circularly and linearly polarized waves and to measure the co-and cross-polar components of the transmission and reflection coefficients of a chiral slab under normal illumination. Then, six experimental measurements are available to retrieve three constitutive parameters. Furthermore, by including the reflection coefficient of the backed metal sample an over determined system of equations is obtained, which leads to increase the accuracy of the material characterization.

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“…The SE of the EMI shield can be expressed as A = 1 − R − T where in the above equations the SE provides details on the desired deactivation mechanisms whereas the coefficients give detailed information about the fractions of EM radiations lost via reflection as well as absorption. 93–96…”

Section: Basic Mechanism Of Emi Shieldingmentioning

confidence: 99%