ZnO之薄膜的第三階非線性折射率

The Third Order Nonlinear Refractive Index of ZnO Film by RZ-scan

由於氧化鋅薄膜的寬能隙與高束縛能，近年來，它已經是一個應用性極大的半導體材料。同時，由於氧化鋅薄膜的透光性，所以其光學特性的研究與應用也日益重要。我們利用RF-magnetron的方式，在氧化鋁基板上濺鍍氧化鋅薄膜，利用反射式掃瞄法（RZ-scan），研究此樣品之第三階非線性折射率（n2）。由此量測系統得到之樣品的移動位置與相對應的反射光強度之曲線圖中，顯示氧化鋅薄膜的第三階非線性折射率為負值。並由量測到之反射光強度與入射光強度等數值，計算求得其n2為6.16X10-4。此外，由實驗中，還發現在低入射光強度的範圍內，第三階非線性折射率的數值與入射光強度成正比關係。The third order nonlinear refractive index n2 has been experimentally observed in ZnO film. which were deposited on the substrates of sapphire, Al2O3 (0001). We determined the third order nonlinear refractive index n2 by using the reflection Z-scan (RZ-scan) technique, in which the reflectance R relative to the location of sample and intensity of incident beam I0 were measured. As nonlinear refractive index exists, the reflectance at the vicinity of X=1 significantly dropped because of the effect of self-defocusing. In this work, we evaluate the values n2 of ZnO thin film 6.16x10-4 . Furthermore, we also found that the value of n2 is linearly dependent on the intensity of incident beam with lower power.