QQ客服 官方微博 反馈留言

题名	光学非线性薄膜中瞬态开孔动态形成过程的实验观测
作者	张兴昊
学位类别	硕士
答辩日期	2015
授予单位	中国科学院上海光学精密机械研究所
导师	魏劲松
关键词	光学非线性，瞬态开孔，超分辨光斑，薄膜，Z扫描
其他题名	Direct observation of the dynamic formation process of transient aperture in nonlinear thin films
中文摘要	本文主要研究了几种常见相变材料的瞬态非线性以及超分辨光斑的形成，对影响材料非线性的因素进行了系统的研究和对比，获得了瞬态开孔动力学形成过程的图像。 介绍了实验中薄膜样品制备的方法，主要是磁控溅射法，若要制备晶态样品，则还需进行退火。然后介绍了薄膜厚度测量及非线性测量的方法。 利用Z扫描装置，我们对几种典型的饱和吸收材料Sb、Ge2Sb2Te5、Sb2Te3、AgInSbTe和反饱和吸收材料InSb的非线性吸收进行了测量，并研究了激发光功率对非线性吸收系数的影响。 为了观测半导体薄膜的瞬态光学非线性响应，我们搭建了一套瞬态透反射信号测量装置，装置中包含一个泵浦光光源（波长为405nm）和一个探测光光源(波长为658nm)，探测光照射在样品上之后分为透射和反射两部分，装置可以同时监测时间尺度为纳秒量级的透射信号、反射信号以及泵浦光信号。利用该装置进行瞬态光孔径以及超分辨形成动力学过程的观测。另外，在样品后方放置高NA的物镜以及ICCD，实现透过样品的瞬态光斑的远场观测。 利用该装置首先对非线性饱和吸收薄膜的光学开孔效应进行测试分析，实验发现，当泵浦光脉冲照射在样品上时，光孔径开始打开，透射率逐渐变大（反射率下降）。当泵浦光脉冲结束的时刻，光孔径完全打开，透射率达到最大值。随后，光孔径缓慢关闭。随后研究了泵浦光功率、泵浦光脉宽等因素对瞬态非线性的影响，发现在一定范围内，泵浦光功率越大、泵浦光脉宽越宽，瞬态非线性效应越明显。但是超出这个范围之后样品会产生不可逆的破坏。然后对于非线性反饱和吸收薄膜进行了光致可逆暗化效应的动力学测试分析，发现在泵浦光作用下，与非线性饱和吸收薄膜相反，InSb薄膜的反射率上升和透射率下降，表现出瞬态可逆的光致暗化效应。 对瞬态透射光斑进行了直接成像观测，发现透过饱和吸收薄膜的超分辨光斑尺寸最小可以达到初始光斑的75%左右，表明这类薄膜有明显的超分辨效应。，而由于光致瞬态暗化效应，透过反饱和吸收薄膜的光斑与入射光斑相比尺寸变大，与理论模拟的结果相符合。
英文摘要	This dissertation mainly studies the transient nonlinearity and the formation of super-resolution light spot in several common phase-change materials, and makes a systematic study and comparison of factors influencing material nonlinearity, dynamic evolution of the optical pinhole channel is detected and imaged, and the transient super-resolution spot is directly captured experimentally. Preparation method of film samples in the experiment, specifically magnetron sputtering method, is introduced. To prepare crystalline samples, annealing is needed. Method of thin film thickness and nonlinearity measurement are then introduced. The nonlinearity of several typical saturable absorption materials (Sb, Ge2Sb2Te5, Sb2Te3, AgInSbTe) and reverse saturable absorption materials (InSb) is measured and the influence of excitation laser power on the nonlinear absorption coefficient is studied. To observe transient optical nonlinear response of semiconductor films, we build a testing setup, which consists of a pump light (405nm) and a probe light (658nm). This setup can monitor transmission, reflection and pump light signals at the same time. Transient optical aperture and super-resolution spot are observed using this setup. The transient nonlinearity of NSA (nonlinear saturation absorption) thin films is studied, and the experimental results show that when pump laser radiates on the sample, aperture starts to open, and the transmittance gets larger while the reflection gets smaller. At the end of the pump pulse, the aperture fully opens, transmittance reaches the maximum. Subsequently, the aperture slowly closes. Then the influence of the power and width of pump pulse on transient nonlinear effects is studied, the results show that within a certain range, transient nonlinear effects will be more evident if pump power is larger or the pump pulse-width is wider. But beyond that range, the sample will be irreversibly damaged. Then films with (NRSA) nonlinear reverse saturation absorption are studied and shows photo-induced darkening effect. The transient transmission beam spot is directly observed using ICCD, and the results show that super-resolution spot sizes through nonlinear saturation absorption film can reduce to 75% of the initial spot, while the size of the spot through nonlinear reverse saturation absorption film becomes larger.
语种	中文
内容类型	学位论文
源URL	[http://ir.siom.ac.cn/handle/181231/16951]
专题	上海光学精密机械研究所_学位论文
推荐引用方式 GB/T 7714	张兴昊. 光学非线性薄膜中瞬态开孔动态形成过程的实验观测[D]. 中国科学院上海光学精密机械研究所. 2015.

个性服务

查看访问统计

相关权益政策

暂无数据

收藏/分享

除非特别说明，本系统中所有内容都受版权保护，并保留所有权利。