發(fā)布時間：2018-05-04 18:46

  本文選題：飛秒激光 + 近場光學(xué)��； 參考：《長春理工大學(xué)》2017年碩士論文

【摘要】：利用納米結(jié)構(gòu)對飛秒激光能量進(jìn)行局域而獲得近場的增強,進(jìn)行納米尺度下光與物質(zhì)相互作用過程的控制,可以實現(xiàn)超衍射空間尺度的納米加工。本文以飛秒激光近場超衍射納米孔加工及周期納米條紋結(jié)構(gòu)制備為應(yīng)用背景,利用有限時域差分法(FDTD),對基于納米結(jié)構(gòu)輔助粒子近場增強(粒子與基底接觸處的電場增強)及其散射場周期條紋分布進(jìn)行了數(shù)值模擬,并對其增強機理及波紋形成物理過程進(jìn)行了分析。在利用納米結(jié)構(gòu)輔助實現(xiàn)超衍射納米加工的近場增強研究方面,通過對近場納米加工用典型輔助粒子(Au、Si和TiO_2)經(jīng)激光輻照后近場分布特性的分析,提出了應(yīng)用高折射率TiO_2介電粒子陣列作為輔助手段誘導(dǎo)激光近場增強的新方案,利用FDTD數(shù)值計算方法對其進(jìn)行了模擬研究。結(jié)果發(fā)現(xiàn),TiO_2粒子將激光能量局域到粒子周圍約100nm空間范圍內(nèi),其空間尺度可以突破衍射極限。而Ti O_2陣列相比于單一粒子,其近場增強幅度下降小于30%,但相對于入射激光而言,仍具有140倍的增強,這非常有利于飛秒激光超衍射加工。同時,理論結(jié)果也表明,幾乎在所有金屬及介電材料表面都可以實現(xiàn)良好的近場增強效果,并且具有隨著基底折射率增加近場逐漸增強的影響規(guī)律。這些現(xiàn)象的產(chǎn)生歸因于TiO_2粒子磁四極振蕩吸收的激光前向場增強效應(yīng)以及粒子與基底近場相互作用過程的結(jié)果。我們獲得的以上結(jié)果對飛秒激光超衍射近場納米加工的應(yīng)用有著重要的意義。應(yīng)對目前飛秒激光直接輻照基底表面形成的周期條紋制備的圖案單調(diào)以及結(jié)構(gòu)清晰度難以保證的不足,開展了材料表面納米結(jié)構(gòu)散射場的周期分布研究。利用球形、正六面體、長方體等典型納米結(jié)構(gòu)計算了其散射場的周期分布,發(fā)現(xiàn)納米結(jié)構(gòu)的形狀、材料及空間分布(納米結(jié)構(gòu)數(shù)量在兩個以上時)對其基底表面散射場分布及強度均有顯著影響,并可以通過改變納米結(jié)構(gòu)參數(shù)進(jìn)行條紋分布的優(yōu)化和控制。這一研究結(jié)果,為超衍射極限空間尺度納米周期條紋結(jié)構(gòu)的制備與優(yōu)化打下了基礎(chǔ)。
[Abstract]:The near field enhancement of femtosecond laser energy is obtained by using nanostructures, and the process of interaction between light and matter at nanometer scale can be controlled, which can realize superdiffraction nanomechanism on spatial scale. In this paper, femtosecond laser near-field superdiffraction nano-hole fabrication and periodic nano-stripe structure preparation are used as the application background. Based on the near field enhancement (electric field enhancement at the contact between particle and substrate) and the periodic fringe distribution of scattering field, the FDTD method is used to numerically simulate the near field enhancement of particles based on nanostructure. The mechanism of enhancement and the physical process of ripple formation are also analyzed. In the near field enhancement study of superdiffraction nanoprocessing by using nanostructure, the near field distribution characteristics of typical auxiliary particles such as Au-Si and TiO-2) after laser irradiation are analyzed. A new scheme of laser near field enhancement induced by high refractive index TiO_2 dielectric particle array is proposed and simulated by FDTD numerical method. The results show that the laser energy is localized to the 100nm space around the particle, and the diffraction limit can be broken by the space scale of TiO-2 particles. Compared with a single particle, the near field enhancement of TiO2 array is less than 30%, but it is still 140 times higher than that of incident laser, which is very favorable to femtosecond laser superdiffraction processing. At the same time, the theoretical results also show that almost all metal and dielectric materials surface can achieve good near field enhancement effect, and with the increase of substrate refractive index, the near field increases gradually. These phenomena are attributed to the laser forward-field enhancement effect of the magnetic quadrupole absorption of TiO_2 particles and the near field interaction between the particles and the substrate. The above results are of great significance to the application of femtosecond laser superdiffraction near field nanocrystalline processing. The periodic distribution of scattering field of nanoscale structures on the surface of materials was studied in order to overcome the monotonous pattern of periodic fringes formed by femtosecond laser irradiation on the substrate surface and the difficulty in ensuring the clarity of the structure. The periodic distribution of scattering field was calculated by using spherical, hexahedron, cuboid and other typical nanostructures, and the shape of nanostructures was found. The material and spatial distribution (when the number of nanostructures is more than two) has a significant effect on the distribution and intensity of scattering field on the substrate surface, and the fringe distribution can be optimized and controlled by changing the parameters of the nanostructure. The results lay a foundation for the preparation and optimization of nanoscale periodic fringes in super-diffractive limit space.
【學(xué)位授予單位】：長春理工大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：TN249;TB383.1

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本文編號：1844202