加上適當的外場時，液晶薄膜內的液晶分子導軸方向將會轉動並且改變液晶薄膜的有效折射率。對於液晶薄膜而言，電場效應比起磁場而言是相當顯著的，所以在應用上常選用電場為其外場。然而藉由在液晶中摻雜磁性粒子，液晶薄膜的磁效應將可以改善，因此除了電場之外磁場將成為影響液晶薄膜的有效折射率的參數之一。
在本篇論文中，我們探討了摻雜磁性粒子液晶薄膜的相位調變能力。電場及磁場對薄膜之相位調變的影響都將加以考慮。我們將先利用液晶薄膜的特性來檢測所準備之薄膜試件的品質，之後利用Khoo所提出的方法去量測在不同電場、磁場下液晶薄膜的相位差。經過我們實驗證明，在磁場的配合之下，磁性粒子的確降低起始電場閥值與調變相位差所需的電場，並且隨著磁性粒子的濃度增加其效果更加明顯。此外我們也發現隨著磁場的增加，可以觀察到磁場飽和的現象，並對此現象，提出合理的解釋。

When the properly external field is applied, the directors of the liquid crystal molecules will be rotated and the effective refractive index of the liquid crystal films will be changed. The electric field is often chosen to be the external field in the application, because the effects of electric filed on liquid-crystal are more significant than those of magnetic filed. However, the magneto-optical effects of the liquid crystal films can be improved by doping with the ferro-nanoparticles. In addition to electric field, magnetic field will become an parameter that is available to control the effective refractive index.
In this paper, the liquid-crystal films in phase modulated property will be presented. The effects of the electric and magnetic fields on the optical characteristics will both be considered. The optical method will be used to test the qualities of the films prepared and then the phase differences will be measured under variable electric and magnetic fields with Khoo’s method. In our experiments, we can show that ferro-nanoparticles can reduce the threshold voltage and the amount of electric field that modulated the phase. The effect is clearer, when the concentration of ferro-nanoparticles increase. Moreover, we can observe the saturation under the gradually increasing magnetic field. About this phenomenon, we provide a explanation in our study.

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