Title page for etd-0718114-224909


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URN etd-0718114-224909
Author Pei-chieh Chou
Author's Email Address No Public.
Statistics This thesis had been viewed 5354 times. Download 21 times.
Department Electro-Optical Engineering
Year 2013
Semester 2
Degree Master
Type of Document
Language zh-TW.Big5 Chinese
Title Photo-Switchable Polarizing Beam Splitter based on Dye-Doped Liquid Crystals
Date of Defense 2014-07-15
Page Count 129
Keyword
  • liquid crystal
  • photo-switchable
  • total internal reflection
  • polarizing beam splitter
  • azo-dye
  • Abstract Polarizing beam splitters (PBSs) split the orthogonal s and p polarizations of the incident light. They are of considerable importance in many optical systems including liquid crystal displays (LCDs), optical communications and optical storage devices. In this study, we aimed to design an active PBS by sandwiching a dye-doped liquid crystal thin layer (ne = 1.7126; no = 1.5287) between two high-index prisms (nprism = 1.778). The working principle of PBS is as follows: As a ray of light propagates from an optically denser medium to a rarer one at an angle larger than a particular critical angle, it is entirely reflected. Such phenomenon is called “total internal reflection”. The birefringence nature of the liquid crystal leads to different critical angles for s-wave and p-wave respectively. Thereby, at a certain angle, the incident light will be divided into two rays with different linear polarizations. In conjunction with an azobenzene dye, the orientational order of the liquid crystal can be optically controlled and so can the effective indices. Under violet irradiation (λ = 404 nm), the azo-dye 1205 experiences an isothermal transition from trans- to cis-state resulting in a phase transition from the nematic to isotropic state; whereas the back-isomerization process can be exerted by green irradiation (λ = 532 nm). Such switching is reversible and bistable. Hence, a photo-switchable and energy-conserving PBS was demonstrated. Moreover, this device can be locally addressed by a spatially modulated pump, which simplifies and enriches the design for further applications.
    Advisory Committee
  • Andy Ying-Guey, Fuh - chair
  • Wei Lee - co-chair
  • Kuang-Yao Lo - co-chair
  • Chi-Yen Huang - co-chair
  • Tsung-Hsien Lin - advisor
  • Files
  • etd-0718114-224909.pdf
  • Indicate in-campus at 5 year and off-campus access at 5 year.
    Date of Submission 2014-08-19

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