光子晶體是一個具有不錯的物理性質，對於電磁波中特定的波長能限制或禁止其繼續傳導的效果。對於特定之波長，光子晶體的製作，主要是選擇使用的晶片及光子晶體的排列。依週期排列的維度又可分為一維、二維及三維的光子晶體，布拉格反射鏡就是一種最常見的一維光子晶體。光子晶體除了能禁止特定波長的電磁波進行傳播外，當在結構中加入點缺陷便可以形成共振腔，而加入了線缺陷則可以做為波導使用。目前有許多光子晶體的應用，如低耗損的介電材質反射鏡、光子晶體微諧振腔、極窄頻濾波器及與光子晶體整合的高效率雷射等。一旦這些元件的開發技術成熟，將有助於實現由光子晶體與其他主動、被動元件構成的高效率積體光路系統。
由於半導體製程及奈米技術之整合，使光通訊應用之領域越來越廣。將光子晶體在鈮酸鋰晶片上製作光子晶體是一個突破。鈮酸鋰為使用在光通訊極佳的材料，常應用在波導元件。結合光子晶體及鈮酸鋰固有之物理調變機致，可使光通訊的應用多元化，成為一個具有調變或選定特定波長的微光電元件。

For electromagnetic, there are some perfect physical properties in the photonic crystal. It can let the particular wavelength forbid propagated to anywhere. The important thing with photonic crystal is arranging the air hole or dielectric column for the period and chooses the material to fabricate it. This excellent property has made photonic crystals useful for communication applications such like narrow-band filters, frequency-selective mirrors, and high-Q cavities. There are more and more evidences that the integration of these photonic crystals, passive and active components will be helpful to realize complex optical circuits.
Due to fabrication of semiconductor and nano-scale technology, we could extent the field of optical communications especially develop a photonic crystal device. Fabricating the photonic crystal on lithium niobate wafer is a novel idea in waveguide applications. To tune the parameter of photonic crystal, there will be more applications for optical communications and can be a excellent micro optoelectric deivce.

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