Some Optical Properties in Ferroelectric-based Photonic Crystals

• Main Authors: Lu, Cai-Chen, 盧采辰
• Other Authors: Wu, Chien-Jang
• Format: Others
• Language: zh-TW
• Published: 2016
• Online Access: http://ndltd.ncl.edu.tw/handle/47815477933809209658

碩士 === 國立臺灣師範大學 === 光電科技研究所 === 104 === 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.