| Summary: | 碩士 === 國立臺灣大學 === 光電工程學研究所 === 95 === With the evolution of technology, traditional CRT has been substituted for TFT-LCD gradually. In the development of LCD, problem of efficiency is always important. The main reason of the reduction of efficiency for LCD is the loss of color filter and backlight module, and we focus on the loss caused by the backlight module in this thesis. Conventionally, DBEF of 3M is used to solve the problem but it is patented. To avoid patent violation, many devices are proposed to take replace of DBEF. According to bibliography, a device with sub-wavelength grating was proposed to achieve polarization splitting and polarization conversion. In such device, design of sub-wavelength becomes very important to achieve satisfying efficiency of polarization splitting.
A suit of commercial software “GSolverTM” is used to design a sub-wavelength grating with high efficiency of polarization splitting. Just as shown in our simulation, there exists the situation of what we called resonance for transmission efficiency of p-ray in blue-light region and that will affect the performance in visible-light spectrum. We provide several solutions to enhance the transmission efficiency of p-ray in blue-light region and try to explain the reason of these solutions. By optimizing geometrical parameters and material of sub-wavelength, we can obtain the sub-wavelength grating well performed in the visible-light region.
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