本研究計畫使用PQ-PMMA高分子感光材料擴散特性搭配雙光束干涉曝光法製作第二階的反射式體積布拉格光柵並且改變曝光強度與時間找最佳的曝光參數，以得到較高的第二階光柵繞射效率。因此本論文首先寫下PQ-PMMA光化學反應速率式，模擬PQ與光產物於曝光時，濃度空間上的分佈情形，並且利用分子濃度計算出空間中折射率變化分佈，並以傅氏級數分析得到PQ及光產物週期性空間分佈之第一階與第二階傅氏振幅，最後使用耦合波理論求得其光柵之繞射效率。實驗上，使用第一階光柵的繞射效率最大值之曝光時間作為評估第二階光柵的繞射效率之重要參數。此方法將得到不同的曝光強度下最佳的第二階光柵之繞射效率。;In this research, a concept of the manufacturing of 2nd order homemade phenanthrenequinone (PQ)-doped PMMA polymer (PQ-PMMA) volume Bragg gratings (VBGs) were proposed that relies on the diffusion characteristics of PQ. Then the rate-equations were written down and used to evaluate the best exposure parameters for diffraction efficiency of 2nd order grating. The simulation can be used to estimate the distributions of PQ and PQ-PMMA which can further determine the distribution of refractive index of PQ-PMMA. Finally, using the Fourier series and coupled-mode equation, the diffraction efficiency of 1st order and 2nd grating can be estimated. Experimentally, the growth curve of diffraction efficiency of 1st order grating was monitored and interrupt exposure at the maximum diffraction efficiency of 1st order grating. Empirically, the maximum diffraction of 1st order grating can be used to evaluate for diffraction efficiency of 2nd order grating. Based on above empirical norm, the best exposure parameters for diffraction efficiency of 2nd order grating can be obtained under different exposed time.
