| 1. |
- Eskandari, Hossein, et al.
(author)
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Design of Nonmagnetic All-mode Waveguide Coupler with Perfect Transmission Using Transformation Optics
- 2019
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In: 13th European Conference on Antennas and Propagation, EuCAP 2019. - : Institute of Electrical and Electronics Engineers (IEEE). - 9788890701887
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Conference paper (peer-reviewed)abstract
- Using the transformation optics method together with the basic properties of Maxwell equations, a compact nonmagnetic waveguide coupler is designed that can ideally couple all TMn modes. Two compression functions are proposed to provide a perfect smooth transition between the waveguides. This coupler can be used to guide and compress a vacuumfilled waveguide to a smaller waveguide with a predefined higher dielectric constant inside. The design method is validated by simulated examples using COMSOL Multiphysics.
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| 2. |
- Eskandari, Hossein, et al.
(author)
-
Elliptical generalized Maxwell fish-eye lens using conformal mapping
- 2019
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In: New Journal of Physics. - : Institute of Physics Publishing (IOPP). - 1367-2630. ; 21
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Journal article (peer-reviewed)abstract
- A circular graded index lens is conformally transformed to an elliptical shape using a closed-form transformation. The proposed transformation is then employed to compress a Maxwell fish-eye and its generalized version. Since the transformation is conformal, the electromagnetic properties of the device are perfectly preserved after the transformation with fully isotropic and dielectric-only materials. Ray-tracing and full-wave simulations are carried out for several cases to verify the functionality of the optically transformed lenses in geometrical optics and wave optics regimes.
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| 3. |
- Eskandari, Hossein, et al.
(author)
-
Extended two dimensional transformation optics for reflection suppression
- 2019
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In: The 10th International Conference on Metamaterials, Photonic Crystals and Plasmonics, META 2019. - : META Conference. ; , s. 1383-1384
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Conference paper (peer-reviewed)abstract
- Here, we demonstrate that by extending the common twodimensional (2D) transformation optics (TO) to the third dimension in an engineered fashion, it is possible to eliminate unwanted reflections from the device boundaries in cases where the compression or expansion of the space makes the ideal transmission of the power impossible in the common formulation. The feasibility of the proposed idea is demonstrated by an example simulated in COMSOL.
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| 4. |
- Eskandari, Hossein, et al.
(author)
-
Transformation optics for perfect two-dimensional non-magnetic all-mode waveguide couplers
- 2019
-
In: Optical Materials Express. - : OPTICAL SOC AMER. - 2159-3930 .- 2159-3930. ; 9:3, s. 1320-1332
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Journal article (peer-reviewed)abstract
- Here, we demonstrate that transformation optics can be used to produce 2-D non-magnetic waveguide couplers with no reflections. Our approach consists of using a scaling function for reflection suppression and introducing an auxiliary function in the transformation optics formulation to achieve a non-magnetic medium for coupling the TM polarization. To demonstrate the potential of this method, two non-magnetic waveguide couplers are designed. The first one satisfies the Brewster angle condition for any arbitrary incidence angle (TMn modes), extending the performance of couplers previously reported in the literature that only operate for TEM (TM0 mode), i.e. waves with normal incidence. Our method can be applied to match any given dielectric constant. Our results demonstrate that for a given mode (angle), we achieve a perfect match to a defined dielectric constant. The second design removes the dependence of the reflectionless condition to the incident angle at the boundary. Hence, this coupler works for all incident angles (TMn modes). It is used to compress all the modes into a region with a higher predefined refractive index.
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