具徑向雙折射液晶殼層光纖之溫度效應

Abstract

液晶是由高度各向異性分子所組成，本文中是將液晶當作光纖波導的外殼層，可使液晶殼層光纖具徑向雙折射特性，因而構成光纖式元件。蝕刻過之光纖所製成之液晶殼層光纖元件，能使液晶接近光纖的消逝場(evanescent field)，改變外在環境變因－溫度，結果改變了液晶的折射率。 本文所探討的輸出光學圖樣是由TE01和HE11兩個模態間干涉的結果，也因此和兩個模態間的相位延遲有關。當外在環境變因－溫度－改變時，液晶折射率改變，兩個模態在光纖式元件中傳播常數改變，但改變量不相等，造成兩個模態間相位延遲發生變化。因此光學圖樣也隨著出現消長情形。

In this thesis, nematic liqued crystals are considered as a cladding layer for a cylindrical fiber waveguide that is optically radially anisotropic. Otherwise, the refractive indies of nematic liquid crystal influency by varing enironmental temperature. We investigate the outpur pattern which is the interference of the two spatial modes, namely, TE01 and HE11, and is dependent of the phase retardation between TE01 and HE11. By controling the ambient temperature and consequently altering the refractive indices of nematic liquid crystals, propagation constants of the two modes are varied, causing the change of the phase retardation between TE01 and HE11. The tidal effect of the output patterns can therefore be observed