利用一維光子晶體對低吸收材料的介電性質、厚度之特性檢測與探討

Abstract

在本論文中，我們利用一維光子晶體結構的性質，應用二種不同的結構設計，藉由量測穿透率值並利用傳輸矩陣法(TMM)計算出最佳化的吸收係數值，改善了在自由空間下對於低吸收材料之吸收係數的檢測結果。同時我們也應用了可調式光子晶體模組的特性，利用穿透頻率的調動結果□成了量測材料在不同頻率下吸收係數值的變化。除了理論的模擬計算外，我們也以微波實驗來驗証我們的結果。 另外我們也提出了應用等效折射率的觀點，對於非導磁性材料經由量測反射係數值，得出介電常數與厚度組成的非線性聯立方程組，最後再利用布洛依登法求解得出待測材料的介電常數、吸收係數與厚度值。

By using the properties of 1-D photonic crystal, we designed two different structures in this thesis. By measuring the transmittance with these structures, we obtained the optimized absorption coefficient by Transfer Matrix Method. Consequently, we improved the accuracy of absorption coefficient measurement for low-loss materials in free-space. At the same time, we applied the tunable modules of photonic crystal to obtain the absorption coefficient in different frequencies with the shift of transmission frequencies. Besides the theoretical simulation, we also verified our result by microwave experiments. In addition, we took the aspect of effective refractive index to nonmagnetic materials. At the end, the Broyden’s Method has been used to solve the nonlinear consociation equations with unknown parameters of dielectric constant and thickness. So that, we can know the dielectric constant, absorption coefficient, and the thickness of the material under test.