本文關(guān)鍵詞：基于超材料的太赫茲吸收體及光開關(guān)的理論研究　出處：《中國科學(xué)院研究生院(西安光學(xué)精密機(jī)械研究所)》2015年碩士論文　論文類型：學(xué)位論文

  更多相關(guān)文章： 太赫茲 超材料功能器件 吸收體 光開關(guān)

【摘要】：超材料(Metamaterials)一般被定義為是一種由亞波長尺寸周期性結(jié)構(gòu)單元構(gòu)成,且具有天然媒質(zhì)所不具有的反常物理特性的新型人工材料�；谶@些獨(dú)特的電磁性質(zhì),該類材料在諸多領(lǐng)域均有廣闊的應(yīng)用前景。尤其是對工作于太赫茲波段的超材料結(jié)構(gòu)的研究工作,目前人們已經(jīng)設(shè)計和制造出了各式各樣的功能器件,包括有太赫茲濾波器、偏振器、調(diào)制器、吸收體和開關(guān)等。相比于傳統(tǒng)器件,它具有易集成和重量輕等優(yōu)點(diǎn)。本論文主要圍繞基于超材料的太赫茲吸收體和光開關(guān)的理論研究及設(shè)計而展開,論文的主要工作內(nèi)容如下:1.提出了一種垂直級聯(lián)的超寬帶太赫茲超材料吸收體。引入了一個由各金屬層磁場諧振耦合而激發(fā)的額外吸收峰,用來增寬吸收譜。疊加之后的吸收譜對2.6-5.7 THz的正入射太赫茲波保持吸收率90%,而且吸收譜的半高全寬(FWHM)約是中心頻率的95%。通過計算各共振頻率的入射太赫茲波功率損耗,分析了額外吸收峰的產(chǎn)生機(jī)理。2.通過仿真研究了太赫茲波入射角和偏振角對吸收譜的影響。結(jié)果表明,當(dāng)入射角不大于50o時,該吸收體仍能在2.5 THz左右的頻率寬度內(nèi)維持吸收率88%。同時,偏振角的改變對吸收譜幅值幾乎不影響。因此該吸收體對入射太赫茲波的偏振不敏感。3.設(shè)計了一個基于非對稱裂環(huán)共振器的太赫茲超材料開關(guān)。通過改變外加泵浦光強(qiáng)可實(shí)現(xiàn)開關(guān)在打開與閉合狀態(tài)之間進(jìn)行切換。從理論上具體研究了硅中載流子濃度與泵浦光強(qiáng)的關(guān)系,以及載流子的產(chǎn)生和衰減過程。4.為了分析光開關(guān)各共振的產(chǎn)生機(jī)理,計算了光開關(guān)在各共振頻率處的電場分布和表面電流分布,結(jié)果發(fā)現(xiàn)有一些共振是由LC共振和高階共振的共振耦合產(chǎn)生。進(jìn)一步,利用兩個簡易模型等效光開關(guān)的打開和閉合狀態(tài),分析了光開關(guān)在工作過程中的模式切換效應(yīng)。5.研究結(jié)果表明,在1.26-1.49 THz的開關(guān)窗口內(nèi),開關(guān)比大于10。改變介質(zhì)層的介電常數(shù)和厚度,可對開關(guān)窗口的位置和寬度進(jìn)行調(diào)節(jié)。調(diào)節(jié)范圍約為0.3 THz。此外,該太赫茲光開關(guān)的響應(yīng)時間可達(dá)到ps量級。
[Abstract]:Metamaterials) is generally defined as a subwavelength size periodic structural unit. New artificial materials with anomalous physical properties that natural media do not possess. Based on these unique electromagnetic properties. This kind of material has a wide application prospect in many fields, especially the research work on the structure of metamaterials working in terahertz band. At present, people have designed and manufactured various functional devices. Includes terahertz filters, polarizers, modulators, absorbers and switches. Compared with conventional devices. This thesis focuses on the theoretical research and design of terahertz absorbers and optical switches based on metamaterials. The main work of this paper is as follows: 1. A vertical cascade ultra-wideband terahertz supermaterial absorber is proposed, and an additional absorption peak excited by magnetic resonance coupling of metal layers is introduced. It is used to widen the absorption spectrum. The superimposed absorption spectra retain an absorptivity of 90% for the normal incident terahertz wave of 2.6-5.7 THz. Moreover, the absorption spectrum FWHM is about 95% of the central frequency. The power loss of the incident terahertz wave at each resonance frequency is calculated. The influence of incident angle and polarization angle of terahertz wave on absorption spectrum is studied by simulation. The results show that the incident angle is less than 50 o. The absorbent can maintain the absorptivity of 88g in the frequency width of about 2. 5 THz at the same time. Therefore, the absorber is insensitive to the polarization of incident terahertz wave. 3. A terahertz supermaterial switch based on asymmetric split ring resonator is designed. The switch switching between open and close states can be realized by adding pump light intensity. The relationship between carrier concentration and pump light intensity in silicon is studied in detail theoretically. In order to analyze the mechanism of optical switch resonance, the electric field distribution and surface current distribution of optical switch at each resonance frequency are calculated. It is found that some resonances are generated by the resonant coupling of LC resonance and high order resonance. Furthermore, two simple models are used to equivalent the open and closed states of optical switches. The mode switching effect of optical switch is analyzed. 5. The results show that the switch window is within 1.26-1.49 THz. The switching ratio is greater than 10. The position and width of the switch window can be adjusted by changing the dielectric constant and thickness of the dielectric layer. The adjustment range is about 0.3 THz. in addition. The response time of the terahertz optical switch can reach PS order.
【學(xué)位授予單位】：中國科學(xué)院研究生院(西安光學(xué)精密機(jī)械研究所)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2015
【分類號】：O441.4;TB39

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