| Summary: | 碩士 === 國立交通大學 === 光電系統研究所 === 104 === The photonic bandgap (PBG) nature of a cholesteric liquid crystal (CLC) is determined by the pitch length and the average refractive index of the CLC. In this study we employed a thermosensitive chiral dopant (TCD), characterized by its thermo-induced change in helical twisting power in terms of the handedness as well as the strength, to shift the central reflection band in the spectrum. We demonstrated the local deformation of the CLC helical structure achieved by the dielectric heating effect. We can apply voltage at various frequencies to control the reflection of incident light so to yield many colors such as red, green, and blue. Moreover, a thermally tunable photonic device was further demonstrated using a one-dimensional asymmetric photonic crystal (PC) infiltrated with the thermosensitive CLC as a defect layer. By means of a temperature controller to shift the PBG of the CLC, the transmission peaks can be tuned in the spectrum dominated by the asymmetric PC structure.
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