THESIS
2022
1 online resource (xiii, 51 pages) : illustrations (some color)
Abstract
In recent years, metasurfaces have attracted a lot of interest in miniaturizing existing
optical components either through achieving a smaller size or through integrating different
functionalities into a single layer of metamaterial atoms. These are mainly due to the current
nano-fabrication capability in putting many nanostructures together in storing a huge amount
of information about the wavefront to be created from the metasurfaces. One prominent
application is hologram displays in very fine resolution. Moreover, different multiplexing
techniques have been explored, e.g., through wavelength, to increase the information capacity
of metasurface holograms. One of which is to perform polarization multiplexing. Currently,
polarization-multiplexed metasurfaces with 3 independent holograms...[
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In recent years, metasurfaces have attracted a lot of interest in miniaturizing existing
optical components either through achieving a smaller size or through integrating different
functionalities into a single layer of metamaterial atoms. These are mainly due to the current
nano-fabrication capability in putting many nanostructures together in storing a huge amount
of information about the wavefront to be created from the metasurfaces. One prominent
application is hologram displays in very fine resolution. Moreover, different multiplexing
techniques have been explored, e.g., through wavelength, to increase the information capacity
of metasurface holograms. One of which is to perform polarization multiplexing. Currently,
polarization-multiplexed metasurfaces with 3 independent holograms have been demonstrated.
To further store more information on the metasurface, it will be desired to have 4 independent
holograms to fully exploit all the 4 matrix elements of Jones matrix or even more degrees of
freedom. In this thesis, I investigate the possibility to incorporate 4 independent holograms
using the full capacity of a Jones matrix. I investigated the symmetries of metamaterial
structures in providing such Jones matrices. I proposed a metasurface design that only uses 2
tunable degrees of freedom in geometry to produce 4 independent holograms. By developing
a modified GS algorithm that applies the phase constraints coming from the designs of metasurfaces directly, one can obtain the required overall metasurface design in obtaining 4
holograms. By using such algorithm, I simulated 2 sets of hologram images, each set of 4
corresponding to the 4 combinations of input and output polarization channels of the Jones
matrix. While I have proved the feasibility of 4 independent holograms with clear features,
the transmission efficiency can be further improved. My findings revealed the possibility of
utilizing all unique polarization channels of a single metasurface. By combining existing
holographic techniques, we may be able to improve the information capacity of metasurface
holograms through more input and output channels such as orbital angular momenta.
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