中强场下稀土离子上转换发光超快控制的研究

发布时间：2018-01-01 05:08

本文关键词：中强场下稀土离子上转换发光超快控制的研究　出处：《华东师范大学》2017年硕士论文　论文类型：学位论文

【摘要】：稀土离子上转换发光被广泛地应用于激光光源、光纤通信、发光二极管、色彩显示和生物系统等领域,因此实时、动态、可逆地控制稀土离子上转换发光对于它们的应用是非常重要的。对于通过光物质相互作用控制多光子吸收过程来说,飞秒激光的相位和偏振调制已经被证明是一种非常简单而且行之有效的方法。在早期的研究中,上转换发光控制主要集中在较弱的飞秒激光场。在这里,我们进一步拓展了这一控制手段,从弱的飞秒激光场进一步拓展到中强的飞秒激光场。在较弱的飞秒激光场中,二阶微扰理论可以很好地解释非共振双光子吸收过程。但是,在中强飞秒场下可以产生更高阶非线性效应(例如,四光子吸收),为此我们建立了一个新的理论模型(也就是四阶微扰理论)来解释这一物理控制机制,这里上转换发光过程涉及了双光子吸收过程和四光子吸收过程。具体研究内容如下:(1)我们通过实验研究和理论分析验证了掺杂Dy3+离子的玻璃上转换发光可以用π相位扫描调制来人为地控制,同时上转换发光控制行为依赖飞秒激光强度。研究结果表明,上转换发光强度在弱的飞秒激光场中可以被有效地抑制,而在强的飞秒激光场中则被增强。理论分析结果显示,在整个激发过程中四光子吸收的相对权重随着飞秒激光强度的增强而增加,而共振双光子吸收和四光子吸收的干涉导致了不同的激光强度下上转换发光调制的改变。(2)飞秒激光场的偏振调制已被证明是控制稀土离子上转换发光的一个很好的方法。我们通过四阶微扰理论模型来研究在中强飞秒激光场的激发下Sm3+掺杂玻璃中的上转换发光的偏振控制行为。实验结果表明,Sm3+掺杂玻璃中的上转换发光的偏振控制效率将受飞秒激光强度的影响,且随激光强度的增加而减小。我们理论上提出四阶微扰理论来解释包括非共振双光子吸收和四光子吸收的实验观察结果,由于其不同的偏振控制程度,双光子和四光子吸收之间的相消干涉将导致偏振控制效率被抑制。
[Abstract]:Rare-earth ion up-conversion luminescence is widely used in laser light sources, optical fiber communications, light-emitting diodes, color display and biological systems, so real-time, dynamic. Reversible control of the upconversion luminescence of rare earth ions is very important for their applications. The phase and polarization modulation of femtosecond laser has been proved to be a very simple and effective method. In the early research upconversion luminescence control mainly focused on the weak femtosecond laser field. We further extend this control method from weak femtosecond laser field to medium strong femtosecond laser field in the weaker femtosecond laser field. The second-order perturbation theory can explain the non-resonant two-photon absorption process well, but the higher-order nonlinear effect (for example, four-photon absorption) can be produced in the medium-strong femtosecond field. Therefore, a new theoretical model (i.e. the fourth order perturbation theory) is established to explain the physical control mechanism. The up-conversion luminescence process involves two-photon absorption process and four-photon absorption process. We have verified that the up-conversion luminescence of glass doped with Dy3 ion can be artificially controlled by 蟺 -phase scanning modulation through experimental research and theoretical analysis. The up-conversion luminescence control behavior depends on the femtosecond laser intensity. The results show that the up-conversion luminescence intensity can be effectively suppressed in the weak femtosecond laser field. The theoretical analysis shows that the relative weight of four-photon absorption increases with the increase of femtosecond laser intensity during the whole excitation process. The interference of resonant two-photon absorption and four-photon absorption leads to the change of up-conversion luminescence modulation with different laser intensity. The polarization modulation of femtosecond laser field has been proved to be a good method to control the upconversion luminescence of rare earth ions. We study Sm3 under the excitation of medium-intensity femtosecond laser field by using the four-order perturbation theory model. Polarization-controlled behavior of up-conversion luminescence in doped glass. The polarization control efficiency of up-conversion luminescence in Sm3 doped glass will be affected by the femtosecond laser intensity. We propose a four-order perturbation theory to explain the experimental results including non-resonant two-photon absorption and four-photon absorption due to their different degree of polarization control. The interference between two-photon and four-photon absorption will result in the suppression of polarization control efficiency.
【学位授予单位】：华东师范大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：O482.31

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