聚-10,12-二十五碳双炔酸Langmuir-Schaefer膜的非线性光学性质

通过飞秒脉冲激光单光束Z 扫描方法研究了聚 10,12 二十五碳双炔酸Langmuir Schaefer膜在非共振吸收区的三阶非线性光学特性。钛蓝宝石激光器的输出脉宽为60～70fs、波长为800nm,在入射光平均功率为145mW时测得其三阶非线性极化率为5.33×10-9esu。这一结果较该类材料的有掺杂的薄膜明显增强,与微晶和单晶达到同样的量级,对此进行了分析和讨论。     

四磺化酞菁氧钒自组装膜的三阶非线性光学性能研究

为提高金属酞菁膜的三阶非线性光学性质,采用静电自组装技术制备出了包含阴离子四磺化酞菁氧钒(VOTsPc)和阳离子聚乙烯亚胺(PEI)交替层的复合薄膜.通过紫外-可见光谱仪表征了VOTsPc/PEI交替多层组装体的组装过程,结果表明组装过程为有规律的连续吸收过程.利用原子力显微镜技术研究了VOTsPc/PEI薄膜的表面形貌,结果表明膜表面是光滑的、均匀的;膜表面紧密堆积了纳米级颗粒,平均粒径为75 nm,平均表面粗糙度为4.406 nm.使用调Q倍频ns/ps Nd∶YAG脉冲激光系统,在输出激光波长为532 nm,脉冲宽度为4 ns条件下,通过Z-扫描测试研究了组装膜的三阶非线性光学性质.通过对实验数据的模拟和计算,30-双层VOTsPc/PEI膜的非线性极化率n2和非线性吸收系数β值分别为4.87×10-6esu和1.2×10-5m/W,三阶非线性极化率χ(3)值为1.57×10-6esu.VOTsPc/PEI膜显示出较强的非线性反饱和吸收性能,具有广阔的应用前景.     

氯铟酞菁光稳定性及光限幅循环特征研究

借助氯铟酞菁(InPcCl)溶液在激光轰击及日照过程中UV-Vis吸收光谱的改变以研究其光稳定性,并采用开孔Z-扫描技术对其光限幅效应及其循环特性进行跟踪研究。结果表明,InPcCl具有良好的光限幅循环特征和在激光轰击下的稳定性,相反,其在日光照射下的稳定性很差。提出了导致这种差异的原因。     

Concentration dependent nonlinear refraction in chloroaluminum phthalocyanine/ethanol solution

Nonlinear refractive properties of chloroaluminum phthalocyanine (CAP) in ethanol solution are studied using the Z-scan technique with picosecond (ps) and nanosecond (ns) laser pulses at a wavelength of 532 nm. A transition from self-focusing to self-defocusing in CAP solution excited by 10 ns pulses is observed during the decrease of its concentration. This transition is due to co-existing excited-state refraction and transient thermal lensing effects. The experimental results are described very well using the rate-equation model and the theory of transient thermal refraction in liquids. The refractive cross sections of the excited-state are also obtained.     

Enhanced Ultrafast Broadband Reverse Saturable Absorption in Twistacenes with Enlarged π-Conjugated Central Bridge

Optical nonlinearities of two all-carbon twistacenes, DPyA and DPyN, with the different π-conjugated central bridges were investigated. The nonlinear absorption properties of these compounds were measured using the femtosecond Z-scan with wavelengths between 650 and 900 nm. It has been found that the nonlinear absorption originated from two-photon absorption (TPA) and TPA-induced excited state absorption (ESA), wherein DPyA demonstrates higher performance than DPyN. The TPA cross section of DPyA (4300 GM) is nearly 4.3 times larger than that of DPyN at 650 nm. Moreover, the different central structures modulate the intensity of ESA at 532 nm, and DPyA exhibits an excellent ESA at 532 nm with multi-pulse excitation. Meanwhile, the result of data fitting and quantum chemistry calculation shows that the enhancement of nonlinear absorption in DPyA is due to the extended π- conjugated bridge and improved delocalization of π-electrons. These all-carbon twistacenes could yield potential applications in optical power limiting (OPL) technology.     

水溶性CdTe:Mn量子点的双光子吸收

采用激发波长800 nm、脉宽50 fs、重复频率1 kHz的Ti:sapphire放大飞秒激光器作为激发光源,利用开孔Z扫描技术研究了不同粒径的CdTe:Mn量子点的非线性吸收性质。理论计算结果表明,同一生长时间CdTe:Mn量子点的双光子吸收系数是CdTe量子点的1.1倍,其双光子吸收系数随量子点尺寸的减小而增大,这是由于CdTe:Mn量子点非线性吸收属于反饱和吸收,掺杂了Mn元素,减小了表面缺陷浓度,表明掺杂量子点具有很好的双光子吸收现象。     

Bis(4,4′-dimethyl-2,2′-bipyridine)ruthenium(II) Complexes Containing 2-Arylimidazo-phenanthroline: Syntheses, Characterization and Third-order Nonlinear Optical Properties

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Synthesis,structure and nonlinear optical properties of three dimensional compounds

The combination of metal ions with H₃tbba has resulted in the formation of two three dimensional coordination compounds {[Zn(H₂tbba)₂(H₂O)] · 2(OC₃H₆)} _n (1) and {[Mn(H₂tbba)₂(H₂O)] · 2(OC₃H₆)} _n (2) (H₂tbba = 2-thiobarbituric acid anion). Compounds 1 and 2 are isostructural with metal ions bridged by four hydroxyl oxygens from four different H₂tbba ligands to form a 3D network. H₂tbba exhibits bidentate coordination with both hydroxyl oxygens participating in coordination, a new coordination mode. Nonlinear absorption and refraction of 1 and 2 in DMF are studied by using Z-scan measurement technique at 532 nm. 1 and 2 possess nonlinear optical absorption and self-focusing.     

Cu7.2S4量子点玻璃的制备及三阶非线性光学性质

利用溶胶-凝胶法结合气氛控制合成了含Cu7.2S4量子点的玻璃. 通过热重-差热分析仪对干凝胶样品的热分解机制进行了分析, 并利用X射线粉末衍射仪、 X射线光电子能谱、 透射电子显微镜、 X射线能量色散谱)、 高分辨透射电子显微镜及选区电子衍射对 Cu7.2S4量子点在玻璃中的微结构进行了表征, 利用飞秒Z扫描技术研究了材料在800 nm的三阶非线性光学性质. 结果表明, 尺寸在9~21 nm之间的Cu7.2S4纳米晶已经在玻璃中形成, 该玻璃展示出了优异的三阶非线性光学性能, 其三阶非线性光学折射率(γ)、 三阶非线性吸收系数(β)和三阶非线性极化率[X(3)]分别为1.11×10-15 m2/W, 8.91×10-9 m/W和9.56×10-18 m2/V2.     

可溶性多壁碳纳米管光限幅机理研究

根据光限幅与Z扫描实验研究了可溶性多壁碳纳米管的光限幅机理.通过现象分析、数据处理以及类比研究,证实材料的光限幅特征符合非线性吸收效应.对厚样品的独特现象进行了解释,讨论了其他机理的影响.根据Z扫描公式,计算了实验材料的三阶非线性系数.通过分析证实了非线性吸收在可溶性多壁碳纳米管的光限幅中发挥着主要作用.对厚介质的特殊现象进行的分析和计算表明,对于较厚介质和激光连续加热的情况下,其他机理的影响并不能完全否定,其特殊现象可能与微气泡的气穴作用有关.