Abstract
在這20年間金屬被覆式偏振器的理論與製作都局限一於一個條件 -使 兩個獨立的模態的傳輸常數的實部必需相同, 在此我們利用模擬的方式在 緩衝層的厚度不是很厚時, 發現此相位相符的條件不是很必要的. 而且在 某一緩衝層控制金屬的厚度可以使得消光比的值為無窮大, 也就是TM模態 的值為零. 此乃因為在偏振器的兩TM模態破壞性干涉而致. 在此篇論文分 別討論了厚金屬及薄金屬的偏振器例子, 不但找出使得消光值為無窮遠的 緩衝金屬的厚度, 並且探討了空氣層對偏振器的影響. The performance of optical metal-clad waveguide polarizers is analyzed in this study with a view to optimizing the extinction ratio. A condition forwhich power of the TM mode is completely attenuated is for the frist time identified here. In general, such a condition corresponding to an infinitelyhigh extinction ratio can be met for a wide range of buffer layer thicknesses by selection of metal film thicknesses and polarizer lengths. When a very thick ( i.e., semi-infinitely thick ) metal film is used, the aforementioned condition can be met with a properly chosen buffer layer thickness and polarizer length. The effect of dielectric-cover-layer thickness on the polarizer performance is also included in the discussion here. From an example of thin- metal-clad wave guide polarizer, we show that an infinitely high extinction ratio canbe realized for a wide range of cover layer thicknesses by selection of metalfilm thickness and polarizer length. The numerical results show that all the polarizers designed here for realization of infinitely high extinction ratioshave either quite low or reasonably acceptable attenuations for the TE mode.