光子晶體是由二或三種以上不同折射率材料週期排列而成的一種結構，在此結構中，某些頻段的電磁波將無法傳遞，這些頻段即為所謂的光子能隙。光子能隙的頻率範圍會受某些條件的改變而影響，例如入射光角度、不同的材料(折射率)或者週期結構的排列方式等。本文中將以幾種不同的數學形式來改變光子晶體結構的排列方式，並觀察其結果的光子能隙增益情形，藉由比較各種方式獲得對光子能隙調變的經驗。

The photonic crystals (PCs) are structures that periodically arranged by two or more different dielectric material. There are bnadgaps in its frequency band, and bandgaps will be changed when we change the structure (such as material, arrangement) or incident angle. In this thesis, we discuss some methods for bandgap modulation in 1-D PCs by change the structure. Above, we have described in Chapter 1.
In here, the basic structure we used is (AB)nA, when AB denote the unit cell, each representing two different material, n is the number of period. In Chapters 3, 4 and 5, we use “power-law” and “linear” and “disorder” three methods to modulate the structure, and we chose the best one by observe their effect. Then we change the material to match the best method, and observe it again in Chapter 6. Finally, in Chapter 7, we make a conclusions.

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