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题名	二维纳米材料制备及超快饱和吸收性能研究
作者	冯艳艳
学位类别	博士
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	王俊
关键词	饱和吸收 石墨烯 二维纳米材料 Z扫描 薄膜
其他题名	The Preparation and Ultrafast Saturable Absorption Investigation of Two-Dimensional Nanomaterials
中文摘要	石墨烯的发现带领很多科研人员进入了二维纳米科技的研究领域，让人们对纳米世界的认知增加了一个“维度”。在石墨烯持续引起注意力的同时，受石墨烯的启发，一系列类石墨烯层状晶体结构特征的化合物，也越来越多的引起了人们的注意并且开始了研究，它们的单层内由强的共价键构成而层间相互作用为弱的范德华力。这类材料像石墨烯那样较容易地制备成二维的单原子/分子层。与体材料相比，二维单层材料由于量子限制效应和层间微扰的缺失，表现出优异的机械、物理、光子学和电子学性质，因而在场效应管、发光LED、光电探测器等领域有着非常广阔的应用前景。将这些二维纳米材料成功器件化并确定其超快非线性光学性质对于未来光子学应用具有重要的意义。本论文中，我们高效制备石墨烯及部分类石墨烯二维纳米材料器件并研究其超快饱和吸收性能，为其在纳米光子器件方面的应用奠定基础。具体包括以下几个部分： 1. Graphene/PVA复合薄膜宽带宽时域饱和吸收性质的研究。 我们将液相剥离的石墨烯分散液与聚乙烯醇（PVA）经过溶液共混法复合成膜。用开孔Z扫描技术研究样品在光纤激光器340 fs，波长1300 nm和515 nm激光以及Nd:YAG 激光器6 ns，波长1064 nm激光下的饱和吸收响应。研究表明，所有波长中相同激发条件下，低透过率的复合薄膜相对于高透过率复合薄膜有着更好的饱和吸收响应；相对于飞秒脉冲，纳秒脉冲激发下薄膜有着更大的饱和吸收系数和品质因子FOM以及更低的Is；在飞秒脉冲下薄膜在近红外的饱和吸收响应比可见光的要强。 2. 不同形态基质对石墨烯近红外域吸收性能的影响。 用开孔Z扫描技术研究有效石墨烯透过率一致的三种形式石墨烯样品在340 fs，波长1300 nm激光下的饱和吸收响应，三种样品分别是液相剥离技术制备的NMP石墨烯分散液，溶液共混法制备的graphene/PVA复合薄膜和真空抽滤再沉积技术制备的纯石墨烯膜。同样的条件下，三种样品中graphene/PVA复合薄膜有着最强的饱和吸收响应和最低的饱和磁化强度Is。由于石墨烯抽滤膜有着很高的线性吸收系数及折射率，因此它的饱和吸收系数和品质因子FOM最大。通过慢饱和吸收模型拟合，得出NMP石墨烯分散液，graphene/PVA复合薄膜和石墨烯抽滤膜的激发态和基态吸收截面均约为~10-17 cm2，它们的比值分别为0.61，0.57和0.71。这些结果对于石墨烯基的饱和吸收器的设计和应用提供很大的参考价值。 3. 二维纳米材料制备、表征和非线性光学性能研究。 扩展上述石墨烯薄膜的制备工艺，分别制备MoSe2，WSe2，MoS2，WS2，BN和石墨烯的胆酸钠分散液、PVA复合薄膜以及抽滤膜样品。其中用液相剥离法制备分散液、溶液共混法制备PVA复合薄膜、真空抽滤再沉积技术制备二维纳米材料的抽滤膜。对各个样品进行TEM、AFM、吸收光谱和拉曼光谱表征，分析其结构特征。用Z扫描技术研究样品中固体薄膜的非线性光学特性，graphene/PVA复合薄膜以及石墨烯和MoS2抽滤膜均表现为饱和吸收特性。此外，成功将MoS2抽滤膜作为饱和吸收体材料应用于Tm:LLF激光实现了被动调Q锁模。
英文摘要	The discovery of graphene leads many researchers in nanoscience field which make people’s perception add a dimension. Gradually, a lot of materials whose structures are similar as graphite, the atoms/molecules within the layer are held by strong covalent forces while interaction between the layers is weak van der Waals force, have attracted considerable attention and can be produced to graphene liked 2D mono-atom/molecule layer. Due to the lack of quantum confinements and interlayer disturbances, 2D material has great mechanical properties photonics and electronics property, therefore have broad application prospects in field-effect transistor (FET), light emitting diode (LED), photodetector, etc. It is significant for photonics applications in the future to explore devices and investigate the nonlinear optical properties (NLO) of these materials. In this report, we prepared 2D material devices, further studied their ultrafast saturable absorption properties, which lay a solid foundation for its application of nanophotonic devices. The contents of this thesis are shown as follows: 1. Saturable absorption behavior of graphene polymer composite films over a broad spectral and time domain. Free-standing graphene-polyvinyl alcohol (PVA) composite films were fabricated by using solution cast method in combination of liquid phase exfoliation. Saturable absorption (SA) responses were observed by using an open-aperture Z-scan technique for 340 fs pulses at 1030 nm and 515 nm from a mode-locked fiber laser, and 6 ns pulses at 1064 nm and 532 nm from a Q-switched Nd:YAG laser. The graphene films possess larger SA coefficient and figure of merit (FOM), and lower saturation intensity Is, for ns pulses than that for fs pulses at the similar near infrared (NIR) wavelength. 2. Host matrix effect on the near infrared saturation performance of graphene absorbers. A comparative research on the near infrared performance of three kinds of widely used graphene saturable absorbers, namely, graphene polymer composite films, neat graphene films and graphene dispersions, was performed by using Z-scan technique with 340 fs pulses at 1030 nm. The polymer films and graphene films were fabricated through solution cast method and vacuum filtration technique based on the liquid-phase exfoliated graphene dispersions, respectively. The polymer films reveal the best SA response and the lowest saturation intensity Is, in comparison with the neat films and dispersions. The graphene films show the largest SA coefficient and figure of merit due to its highest linear absorption coefficient and refractive index. By employing slow SA modeling, the excited state and ground state absorption cross sections were estimated to be ~10-17 cm2, and the ratio were 0.61, 0.57 and 0.71 for the dispersions, polymer films and neat films, respectively. 3. Preparation, characterization and ultrafast NLO research of two-dimensional crystalline material. Dispersions, polymer compsite films and neat films of MoSe2，WSe2，MoS2，WS2，BN and graphene were prepared in this work. The polymer films and neat films were fabricated through solution cast method and vacuum filtration technique based on the liquid-phase exfoliated dispersions, respectively. All the samples were verified by TEM, AFM, UV-Vis and Raman characterization. The research on the NLO of the films was performed by using Z-scan technique. The graphene/PVA film, graphene neat film and MoS2 neat film exhibited SA response. A passively Q-switched mode-locked Tm:LLF laser with a MoS2 saturable absorber was demonstrated successfully.
语种	中文
内容类型	学位论文
源URL	[http://ir.siom.ac.cn/handle/181231/15936]
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	冯艳艳. 二维纳米材料制备及超快饱和吸收性能研究[D]. 中国科学院上海光学精密机械研究所. 2015.

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