尚光网 本站首页 本所首页 联系我们
chi20191128上海光机所张龙557642Laser technology becomes faster and stronger, so the nonlinear optical properties of materials under ultra-fast laser have great potential applications. At present, most of the research work focuses on the experiment of nonlinear optical response of materials. Defects exist in every nano material. Effect of Defect on Nonlinear optical properties of Nanoscale materials was barely studied. We want to testing the nonlinear optical properties of materials, studying the generation mechanism of the nonlinear optical response of materials, finally, designing the photoelectronic structure of materials. This work has great challenge. So far, we made several kinds of nanomaterials, and studied the ultrafast nonlinear optical properties of these materials. The third order nonlinear absorption was measured by an ultrafast nonlinear measurement system with femtosecond laser as the light source. The principle of nonlinear optical response of materials was analyzed by electron paramagnetic resonance measurements, pump-probe and other test systems. The main contents are as follows: 1. We have studied the nonlinear absorption properties of bismuth oxychlorides (BiOCl) single-crystalline nanosheets with {001} and {010} facets under the excitation of 340 fs pulses at 515 nm through a typical Z-scan setup. We found that all the BiOCl nanosheets exhibit a reverse saturable absorption and the effective nonlinear absorption coefficient of BiOCl with {010} facet is found to be ca 1.5 times of that of {001} one. According to the results of photoluminescence and electron paramagnetic resonance, excited-state absorption is found to prevail over two photon adsorption during nonlinear optical process, and the facet-correlated performance of BiOCl nanosheets is attributed to the localization of excited carriers correlated with defect density and size of atomic slab. This work successfully adjusted the nonlinear absorption coefficient of material by changing the ratio of exposed crystal, and proposed a new way for the control of the nonlinear optical properties of layered materials. The defects have a positive effect on the nonlinear optical properties and promote the RSA in BiOCl. 2. We studied the nonlinear optical properties of Mo nano-films with 340 fs laser with the wavelength of 515 nm and 1030 nm through a typical I-scan setup. We found that Mo nano-film exhibit a strong reverse saturable absorption (RSA) in both 1030 nm and 515 nm. The effective nonlinear optical coefficient is on the order of 10^3 to 10^4 cm/GM in both 1030 nm and 515 nm, much larger than typical semiconductors. It is worth noting that different from semiconductors the Mo nano-films exhibit outstanding RSA performance in both 515 nm and 1030 nm, which can give a solution to the problem of narrow protective wavelengths in laser protection. The results reveal a non-precious metal with extraordinary nonlinear optical performance, which has a great potential in nonlinear optical devices. We have studied the nonlinear absorption properties of Mo nano-film with different thickness. The nonlinear optical coefficient becomes bigger with the increase of thickness. Thought of the electrical structure of Mo nano-film and the free-carrier absorption system, the RSA might come from free-carrier absorption. The nonlinear optical coefficient was correlated to on the thick of samples, arising from defects in crystallinity. The thickness-correlated performance of Mo nanofilm is attributed to the free carriers correlated with defect density in the materials. It turns out that the Mo nano-film has excellent nonlinear optical properties and great application potential in the field of laser protection. For Mo nanofilm, the sample with fewer lattice defects has better nonlinear absorption performance, and the defect has a negative effect on the nonlinear optical absorbance. 3. Nonlinear optical properties, in which optical parameters of nonlinear medium are affected by the intensity of inset laser, exist widely in modern photonic systems. However, the nonlinear optical properties are often difficult to control in a given material and dynamical control of optical nonlinearities still confined to research laboratories as a spectroscopic tool by now. Here, we report a theory of electrically control nonlinear optical absorption in tungsten trioxide thin film semiconductor. We find that the intensity of nonlinear optical absorption is tunable by over two orders of magnitude, the nonlinear optical coefficient nearly a factor of 50 times at room temperature through electrostatic doping in a field-effect transistor. Such tunability arises from the strong exciton charging effects in semiconductors. The nonlinear optical absorption is related to the dynamics of charging between bad-gap, which controlled by impressed voltage. Our study provides a new way towards electrically tunable nonlinear optical devices based on semiconductors.2020atalunwen22169385336Nanomaterial;Third-order Nonlinear Optical;Reverse Saturable Absorption;Free Carriers Absorption;Pump-ProbeModulation Research on Ultra-fast Nonlinear Optical Properties of Low-dimension Semiconductor低维半导体材料超快非线性光学性能调制研究随着现代激光技术向更快、更强的领域发展,在超快激光作用下发生非线性光学响应的材料具有巨大的潜在应用价值。纳米材料由于其在尺寸、性能、成本上的优势成为当今非线性光学材料的研究热点。缺陷是纳米材料结构中无法避免的存在,但是对于缺陷在材料非线性光学性能中的作用的研究较少。通过对材料非线性光学性质的测试,研究材料非线性光学响应的产生机理,探索结构缺陷在性能上的影响,进一步对材料的电子结构进行设计,研制出符合应用需求的非线性光学材料,这项工作具有巨大的应用价值和科学价值。对于现阶段本论文利用水热法、磁控溅射法等多种手段制备多种纳米材料,通过对材料的非线性光学性能的影响掌握其性能特点,进而对产生非线性光学响应的光电子运动情况进行研究,并对材料进行结构设计,以达到调控材料非线性光学性能的目的。实验主要采用以飞秒激光为光源的超快非线性测试系统进行非线性吸收的测试,利用电子顺磁共振,泵浦探测等测试系统对材料产生非线性光学响应的原理进行分析,深度研究了材料中光电子的活动情况,对调控材料非线性光学性能的手段进行了新的尝试。具体的研究内容如下: 1. 我们通过典型的Z扫描装置,研究了具有不同缺陷量的暴露晶面分别为{001}和{010}的氯氧化铋单晶纳米薄片在515 nm、340 fs脉冲下的非线性光学吸收特性。我们发现所有的氯氧化铋纳米薄片都表现出反饱和吸收现象,而且{010}晶面氯氧化铋的有效非线性吸收系数是{001}晶面氯氧化铋的1.5倍。进一步研究了材料的非线性光学原理,并通过双光子荧光实验和电子顺磁共振测量解释了氯氧化铋中缺陷影响的非线性光学性质。根据实验的结果,发现与双光子吸收相比,缺陷带来的激发态吸收对非线性吸收的影响更大,所以不同晶面结构的氯氧化铋的非线性光学性能会有区别。该项工作成功利用改变暴露晶面比例实现调节材料非线性吸收系数的目的,为层状材料非线性光学性能的调控提出了一种新的途径。另外在氯氧化铋半导体材料中,缺陷对其非线性光学性能带来了正面的影响,促进材料的反饱和吸收。 2. 通过典型的I扫描装置,研究了波长分别为515 nm和1030 nm的超快激光下钼纳米薄膜的非线性光学吸收特性。我们发现钼纳米薄膜在1030 nm和515 nm波长处均表现出强的反饱和吸收现象,非线性光学吸收系数在1030 nm和515 nm处均达到10^3~10^4 cm/GM量级,这一结果远远大于一些典型半导体的非线性吸收系数。与经典半导体材料不同,钼纳米薄膜在515 nm和1030 nm两种波长下均表现出优异的反饱和吸收性能,解决了激光防护中保护波长过窄的问题。我们还研究了不同厚度钼纳米薄膜的非线性吸收特性。随着厚度的增加,非线性吸收系数增大。考虑到钼纳米薄膜的电子结构和自由载流子吸收体系,钼纳米薄膜的非线性光学性能与材料中自由载流子寿命有关。结果表明,非贵金属钼纳米薄膜材料具有优异的非线性光学性能,在激光防护领域中具有巨大的应用潜力。对于金属钼纳米材料,晶格缺陷越少样品的非线性吸收性能更好,缺陷对非线性光学性能起到了抑制的作用。 3. 探索了缺陷对半导体纳米材料的非线性光学性能的动态调制。我们研究了电控三氧化钨纳米薄膜晶体管的非线性光学吸收理论,利用缺陷的动态调控——外加电场的手段,对三氧化钨晶体管的非线性性能进行调控。通过缺陷的动态调控手段,可使三氧化钨纳米薄膜晶体管的非线性光学系数变化达50倍,这种可调谐性来自半导体中强激子充电效应,样品的非线性光学吸收与外加电压控制的带隙间电动力学有关。我们的研究为基于半导体缺陷的电调谐非线性光学器件提供了一条新的途径。纳米材料;三阶非线性光学;反饱和吸收;自由载流子吸收;泵浦探测中国科学院上海光学精密机械研究所李卉材料学博士
中文题目: 低维半导体材料超快非线性光学性能调制研究
外文题目: Modulation Research on Ultra-fast Nonlinear Optical Properties of Low-dimension Semiconductor
作者: 李卉
导师姓名: 张龙
学位授予机构: 中国科学院上海光学精密机械研究所
答辩时间: 20191128
中文关键词:
纳米材料;三阶非线性光学;反饱和吸收;自由载流子吸收;泵浦探测
英文关键词:
Nanomaterial;Third-order Nonlinear Optical;Reverse Saturable Absorption;Free Carriers Absorption;Pump-Probe
中文摘要:
英文摘要:
文献类型:学位论文
学位级别: 博士
正文语种: chi
clickdetails
页面点击量: 40
文章下载量: 1
visitlog
友情链接:
  上海大恒公司
  南京先进激光技术院
  光学产品库

版权所有 © 2009 中国科学院上海光学精密机械研究所 沪ICP备05015387号-18
主办:中国科学院上海光学精密机械研究所 上海市嘉定区清河路390号(201800)