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Design of metasurfaces for advanced optical elements
Březina, Tomáš ; Kvapil, Michal (referee) ; Hrtoň, Martin (advisor)
Metasurfaces represent an intriguing class of materials with a wide range of promising applications, one of them being advanced planar optical elements for industrial production and imaging. The main goal of this thesis is to design such an optical element, namely a beam-shaper consisting of dielectric anostructures in HCTA (high constrast transmitarray) arrangement. The first part of this work introduces a simplified theoretical model of the optical response of building blocks that facilitates understanding of the basic functional mechanism behind the phase metasurfaces. To quantify the optical response of dielectric building blocks with enough precision, numerical FDTD simulations were employed. As a result, a database compatible with lithographic fabrication procedures was created. To find the phase distribution ensuring the desired beam-shaping function, two approaches were investigated and implemented: the semi-analytical method of geometric transformation and the iterative Gerchberg-Saxton algorithm. The final output of this work is then the distribution of building blocks within the metasurface that imprints into the impinging beam the previously calculated phase profile.
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A Brief Design of Optical Resonators
Hubík, Daniel ; Nešpor, Dušan (referee) ; Kadlec, Radim (advisor)
This bachelor thesis is focused on analysis of split-ring resonators in THz region. Simulations were made by finite elements method and by finite-difference time-domain method. At first we created a resonating structure that works in GHz region. Then we were observing a dependence of movement of resonant frequency on the size of resonator. In the final chapter we assigned frequency dependent values of permitivity to such structure. As the result we simulated working resonator at frequency 500THz. All simulations have been made in program HFSS ANSYS and Lumerical FDTD Solutions.
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Design of metasurfaces for advanced optical elements
Březina, Tomáš ; Kvapil, Michal (referee) ; Hrtoň, Martin (advisor)
Metasurfaces represent an intriguing class of materials with a wide range of promising applications, one of them being advanced planar optical elements for industrial production and imaging. The main goal of this thesis is to design such an optical element, namely a beam-shaper consisting of dielectric anostructures in HCTA (high constrast transmitarray) arrangement. The first part of this work introduces a simplified theoretical model of the optical response of building blocks that facilitates understanding of the basic functional mechanism behind the phase metasurfaces. To quantify the optical response of dielectric building blocks with enough precision, numerical FDTD simulations were employed. As a result, a database compatible with lithographic fabrication procedures was created. To find the phase distribution ensuring the desired beam-shaping function, two approaches were investigated and implemented: the semi-analytical method of geometric transformation and the iterative Gerchberg-Saxton algorithm. The final output of this work is then the distribution of building blocks within the metasurface that imprints into the impinging beam the previously calculated phase profile.
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A Brief Design of Optical Resonators
Hubík, Daniel ; Nešpor, Dušan (referee) ; Kadlec, Radim (advisor)
This bachelor thesis is focused on analysis of split-ring resonators in THz region. Simulations were made by finite elements method and by finite-difference time-domain method. At first we created a resonating structure that works in GHz region. Then we were observing a dependence of movement of resonant frequency on the size of resonator. In the final chapter we assigned frequency dependent values of permitivity to such structure. As the result we simulated working resonator at frequency 500THz. All simulations have been made in program HFSS ANSYS and Lumerical FDTD Solutions.
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