鐵電光子晶體的光學性質

Abstract

在本文中，我們將研究以鐵電光子晶體為基礎的一些光學性質。我們數值研究有缺陷的介電光子晶體在含有鐵電缺陷的太赫茲(THz)濾波器性質。我們研究兩個光子晶體結構於我們的研究中。首先，我們考慮一個濾波器的結構，空氣air/(BA)ND(BA)N/air，其中B為石英，A為空氣，D為鐵電材料鉭酸鉀KTaO3（KTO），和N為堆疊數。我們研究以轉移矩陣法（TMM）為基礎計算出的透射響應的濾波性質。鉭酸鉀KTaO3（KTO）的介電常數是一個強大的溫度函數在太赫茲(THz)頻率，我們證明一個熱可調濾波器可以實現的，即信道頻率會隨著溫度的變化轉移。此外，鐵電缺陷的厚度在量測多通道濾波器時是一個重要參數。我們也證明出，增加厚度可明顯增加信道數。我們考慮的結構可因此被設計為可調式太赫茲(THz)和多通道濾波器的太赫茲(THz)光電子。第二，我們考慮多信道濾波器結構在一個有限的光子晶體設計中，air/(BA)ND(BA)N/air，其中A為氧化鎂MgO，B為鉭酸鉀KTaO3（KTO）。在此證明出信道數N的數量為N-1，特別的是信道頻率的溫度為可調式的。熱可調多通道濾波器技術使用在光子用途。最後，我們對於KTO/MgO在一個無限的光子晶體在光子能帶間隙（PBG）結構的變化進行研究。我們研究出光子能帶間隙（PBG）在溫度可調的影響。

In this thesis, we shall study some optical properties in ferroelectric-based photonic crystals (PCs). We numerically study the terahertz (THz) filtering properties for a defective dielectric photonic crystal containing a ferroelectric defect. There are two photonic crystal structures in our studies. First, we consider a filter structure, air/(BA)ND(BA)N/air, where B = quartz, A =air, D is a ferroelectric material of KTaO3 (KTO), and N is the stack number. We investigate the filtering properties based on the use of the transmittance response calculated by the transfer matrix method (TMM). With the permittivity of KTO being a strong function of the temperature at THz frequency, we show that a thermally tunable filter can be achieved, i.e., the channel frequency will be shifted as the temperature varies. In addition, the thickness of ferroelectric defect also is an important parameter in the determination of the number of multiple channels of a filter. We show that an increase in the thickness can significantly increase the number of channels. The considered structure can thus be designed as a THz tunable and multichannel filter which is of potential use in THz photonics. Second, we consider a design of multichannel filter structure for a finite PC, air/(AB)N/air, in which A is a dielectric of MgO and B is KTO. It is shown that the number of channels is just equal to N-1 and particularly the channel frequencies are temperature-tunable. The thermally tunable multichannel filter is of technical use in photonic applications. Finally, the temperature dependence of photonic band gap (PBG) structure for an infinite PC of KTO/MgO will be investigated. We will investigate how the PBG is affected by the temperature.