文中基于量子阻抗洛伦兹振子（Quantum Impedance Lorentz Oscillator, QILO）模型，研究了含芴二茂铁衍生物的单、双、及三光子吸收特性。首先，理论推导并给出了用有效量子数、电子电量及质量和玻尔半径等微观量表示的该振子四、五阶非线性效应参量的计算参考公式。在此基础上，利用QILO模型，通过拟合取代基为R=NO₂的含芴二茂铁衍生物分子线性吸收光谱，得到了其在400 nm峰值附近的电子跃迁前后的有效量子数，并进一步推算了该分子的双、三光子吸收截面。数值计算结果显示：该化合物分子在793 nm波长附近的双光子吸收截面为 $0.49\times {10}^{-20}\;{\mathrm{c}\mathrm{m}}^{4} \cdot {\mathrm{G}\mathrm{W}}^{-1}$，在1 260 nm和1 314 nm附近的三光子吸收截面分别为 $2.01 \times {10}^{-25}\;{\mathrm{c}\mathrm{m}}^{6}\cdot{\mathrm{G}\mathrm{W}}^{-2}$、 $1.00\times {10}^{-25}\;{\mathrm{c}\mathrm{m}}^{6} \cdot {\mathrm{G}\mathrm{W}}^{-2}$，与实验结果均吻合较好。文中结果说明：QILO模型可以较好地描述以NO₂作为取代基的含芴二茂铁衍生物的单、双、及三光子的吸收特性。根据QILO模型的“依据介质的线性吸收光谱可以估算其多光子吸收截面”的特点，该模型或许能为寻找具有大的双、三光子吸收截面的材料提供一种可供参考的理论分析方法，降低研究多光子过程的综合实验成本。

多光子成像具有零背景下可见光信号输出的优势，但传统多光子探针激发域值高、光稳定性差的问题使其在生物应用中受到限制。基于稀土上转换的无机纳米粒子可在相对较低的激发光功率密度下实现稳定的上转换发光，因而成为一种重要的多光子探针。随着成像技术的进步，对上转换纳米粒子的研究正在从聚集体形式向单颗粒水平发展。单颗粒研究上转换发光不仅有利于排除环境因素的干扰，并且呈现出一系列与聚集体研究不尽一致的理论成果。由于单颗粒研究平台更加接近于探针生物成像的工作环境，因此在这一水平下对上转换纳米粒子进行材料优化与物理机制分析更贴近实际应用。本文从多光子发光机制与材料出发，重点围绕着单颗粒水平下上转换纳米粒子近年来的研究成果与应用进展进行了综述，最后对其未来的研究方向进行了展望。

Medical femtosecond laser devices are used in dermatology for non-linear high-resolution imaging to obtain non-invasive and label-free optical skin biopsies (multiphoton tomography) as well as in ophthalmology for refractive corneal surgery and cataract surgery. Applications of commercial certified multiphoton tomographs include early detection of skin cancer within minutes by two-photon autofluorescence imaging of coenzymes and melanin and second harmonic imaging of collagen as well as by testing the efficacy of pharmaceutical and cosmetical products. Goals are (i) to reduce the number of physically taken human skin biopsies in hospitals and research institutions, (ii) to optimize personalized medicine, and (iii) to reduce animal studies in pharmacy. Current diagnostic tools in dermatology include surface microscopy with a dermatoscope and ultrasound but have poor resolution. Optical coherence tomography and confocal reflectance microscopy have better resolution but provide limited information based on changes of the intratissue refractive index. Multiphoton tomography provides the best resolution of all clinical imaging methods and offer functional imaging such as optical metabolic imaging based on autofluorescence lifetime imaging. Goals of femtosecond laser eye treatment are (i) the replacement of mechanical microkeratomes for corneal flap generation, (ii) the replacement of the UV nanosecond excimer laser for stroma removal, and (iii) to replace, in part, the scalpel in the surgery of cataracts and other eye diseases. So far, millions of eye treatments have been conducted around the world. The major disadvantage of current certified medical femtosecond laser devices is the high price compared with the standard mechanical and optical medical devices.

Multiphoton microscopy is the enabling tool for biomedical research, but the aberrations of biological tissues have limited its imaging performance. Adaptive optics (AO) has been developed to partially overcome aberration to restore imaging performance. For indirect AO, algorithm is the key to its successful implementation. Here, based on the fact that indirect AO has an analogy to the black-box optimization problem, we successfully apply the covariance matrix adaptation evolution strategy (CMA-ES) used in the latter, to indirect AO in multiphoton microscopy (MPM). Compared with the traditional genetic algorithm (GA), our algorithm has a greater improvement in convergence speed and convergence accuracy, which provides the possibility of realizing real-time dynamic aberration correction for deep in vivo biological tissues.

用计算量子场论方法研究了非线性啁啾频率对势阱中正负电子对产生的增强效应。研究了由静态势阱和动态势阱组成的组合势阱中产生的正负电子对的密度、产额和能谱等性质随着啁啾参数的变化，分析了组合势阱的频谱和瞬时束缚态。发现非线性啁啾效应对低频区域比较敏感，与固定频率情况相比可以使粒子数增加2～3倍。与组合势阱相比，非线性啁啾效应对单个振荡势阱更敏感。在低频下单个振荡的势阱中正负电子对产额可提高多个数量级。这是因为在低频下单个振荡的势阱中，主要通过量子隧穿过程产生的正负电子对数目非常低。非线性啁啾效应增加了高频场成分，提高了多光子过程和动力学辅助机制。由于高频抑制作用，所以非线性啁啾效应对高频区域粒子的增量不大，甚至会抑制正负电子对的产生。