結合Ge2Sb2Te5相變化材料與準波導模態之窄頻波長可調式熱輻射發射

Abstract

本論文旨在設計與實現一種具連續波長可調特性的窄頻熱輻射發射器，結合非對稱光柵結構與相變化材料鍺銻碲合金（Ge₂Sb₂Te₅, GST），針對中紅外波段之斜向出射特性進行分析。根據破壞結構對稱性所引起布里淵區摺疊（Brillouin zone folding）之原理，模擬中設計出能在目標波長處產生高Q值且具備角度色散特性的準波導模態（Quasi-guided mode, QGM）共振的非對稱GST光柵結構。透過數值模擬分析不同偏振態（TE與TM）下的能帶分佈，並藉由調整光柵線寬、間距與GST厚度等參數，成功模擬出三種不同狀態之熱輻射調控結果，分別對應於aGST狀態下的TM偏振QGM共振出射、aGST狀態下的TE偏振QGM共振出射以及36%cGST狀態下的TE偏振QGM共振出射，展現約2 μm之連續可調光譜範圍並維持高Q值特性。在實驗部分，採用雷射直寫技術完成光柵樣品製作，惟受限於實際製程設備，部分結構參數需進行修正後，再利用修正後的模擬結果與實驗比對，透過改變偏振方向及控制GST相變化，仍可實現約1.5 μm之連續光譜可調範圍。綜合而言，本研究所提出之非對稱光柵結合相變化材料複合結構能以偏振方向、出射角度與材料相變等多重參數調控共振位置，達成大範圍連續可調的窄頻熱輻射響應，兼具高Q值與製程簡化之優勢，對未來可調式中紅外熱輻射與高靈敏分子感測元件之發展具有重要參考價值。

This thesis presents the design and implementation of a narrowband thermal emitter with continuously tunable wavelength characteristics in the mid-infrared region, specifically analyzing its oblique emission properties. By integrating an asymmetric grating structure with the phase-change material Ge₂Sb₂Te₅ (GST), the design utilizes Brillouin zone folding induced by symmetry breaking to generate high-Q Quasi-Guided Mode (QGM) resonances. Numerical simulations were performed to analyze band distributions under both TE and TM polarizations. By systematically optimizing parameters such as grating linewidth, period, and GST thickness, the study successfully demonstrated three distinct thermal radiation modulation regimes: TM-polarized QGM (aGST), TE-polarized QGM (aGST), and TE-polarized QGM (36% cGST). These configurations exhibit a continuously tunable spectral range of approximately 2 μm while maintaining high Q-factors. Experimentally, samples were fabricated using Direct Laser Writing technology, with structural parameters adjusted to account for manufacturing equipment constraints. By correlating the experimental results with revised simulations, a continuous tuning range of approximately 1.5 μm was achieved through the manipulation of polarization direction and GST phase transition. In summary, this research highlights that the proposed asymmetric composite structure allows for versatile resonance control via polarization, emission angle, and phase changes. This method offers a scalable solution for wide-range tunable thermal emission with high Q-factors, providing significant value for the development of future mid-infrared sensing devices.