Broadband spectral splitting of light using wavefront shaping

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2018
Başay, Yalın
Splitting of light to different frequencies is an important tool for several photonic research and applications. One of those applications is increasing the absorption of light via spectral splitting in solar energy systems. Nowadays, this splitting process is realized by fixed diffraction gratings. However, these structures can't adapt to the environmental changes and their efficiencies differ from season to season. A structure that can adapt to environmental changes would certainly increase the efficiency of solar energy systems. When the dimensions of a medium are comparable to wavelength of light, diffraction plays a major role in wave propagation and it differs by wavelength. Thus, it is possible to obtain intended phase difference for each frequency by changing the thickness or refractive index of the medium. As a result, waves at a specific frequency can be controlled to constructively interfere at a desired point. Liquid crystal displays, which enable to control refractive indices of each pixels via modulating the amplitude of the applied electric field can be used to control diffraction. By this programmable control, the spatial phase of light can be changed between 0-2π and the phase pattern for spectral splitting can be determined. As a result, light can be spectrally split using an adaptive medium. In this thesis, we will use liquid crystal displays to determine a micro structure that can achieve spectral splitting at different angles of incident light. In accordance with this purpose, spectral splitting of light will be customized to a region or a building. In addition, we will also investigate the effectiveness of the spectral splitting and the splitting ratio. Our spectral splitting patterns promise an increase in solar cell efficiency given that the effectiveness will be customized to the location where the solar cell will be positioned.
Citation Formats
Y. Başay, “Broadband spectral splitting of light using wavefront shaping,” M.S. - Master of Science, Middle East Technical University, 2018.