線性電光效應（Pockels 效應）在雷射相關領域的發展及應用上有著舉足輕重的地位。例如雷射共振腔內的電光Q-SWITCH （Pockls Cell Switch）。而一套方便的計算電光係數的模擬方法能有助於線性電光效應材料的研究與相關技術發展。 現有的計算電光係數方法有陳創天教授等所提出，從計算 著手進而得到電光係數[14]，以及王鼎盛教授研究群所使用，直接計算 ，得出電光係數[15,16]。而本篇論文中我們嘗試從電光效應最基本的定義著手 ─ 藉由外加低頻電場所引發的折射率改變。我們使用Finite E-Field加電場的古典方式，並只做靜電場加以近似，以CASTEP進行電子結構以及光學計算，Materials Studio介面分析求出折射率，然後代入公式求得電光係數。 另外，為了克服Finite E-Field加電場方式會在連續性週期晶胞內造成電位能落差大的非物理區域問題，而發展的Zone-Grid cutting波函數切割工具，也是本篇論文中研究發展的項目之一。 The linear electro-optic (E-O) effect (or Pockels effect) is of great importance to the development of laser science and technology. For example, Pockels cells are always used in the electro-optic Q-switch of laser cavity. A convenient computational simulation method for E-O coefficient will be useful to the development of these materials.
There are methods that exist for calculating E-O coefficient, such as the one proposed by Prof. Chuang-Tian Chen''s group, they got the E-O electro-optic coefficient by calculating , another one was by Prof. D. S. Wang''s group, they calculated the E-O electro-optic coefficients directly through a formalism. In this research we tried to use the basic definition of the E-O effect, which is related to the change of refractive index caused by low frequency external electric field. We approximated the low frequency electric field by a static electric field by using the Finite E-Field method, and then calculate the electronic structure and optical properties by CASTEP. We then analysed the refractive index by Materials Studio, then substitution into the formula to get the E-O coefficient.
Furthermore, the Finite E-Field method using in a period crystal calculation will induce a non-physical area between two neighbor cells. In this research also, we develop a program called Zone-Grid cutting program to overcome this problem.
