C60溶液的无规界面光限幅实验

研究了具有无规界面的Ｃ６０甲苯溶液的光限幅效应，实验结果表明，光限幅起源于激发态吸收和无规界面散射，限幅箝位值低于Ｃ６０溶液的激发态吸收限幅箝位值。     

对称型长共轭芴类衍生物的溶致变色效应及光限幅性能研究

通过Heck反应得到3个含有不同末端基团的对称型长共轭芴类衍生物(M1-M3),化合物结构通过NMR、IR和元素分析表征。测试了3个化合物THF溶液的紫外吸收光谱、荧光光谱和荧光量子产率,同时研究了它们在不同极性溶剂中的溶致变色效应。通过Z-扫描技术,得到3个化合物在不同入射激光能量下对应的非线性吸收系数β和双光子吸收截面σ。并对它们的皮秒光限幅性能进行了研究,结果发现M2和M3具有较好的光限幅性能。通过限幅机制分析,M2和M3的光限幅性能主要来源于双光子吸收机理。     

金属团簇化合物W2Ag4S8(dppf)2激发态非线性光学性质

用Z扫描方法测量了金属团簇化合物W2Ag4S8(dppf)2的非线性光学响应,发现团簇W2Ag4S8(dppf)2具有显著的反饱和吸收和自聚焦等非线性光学性质.应用激发态理论分析了团簇W2Ag4S8(dppf)2的非线性吸收和非线性折射,结果与实验数据一致.通过数值模拟获得激发态和基态吸收截面比值Ka及非线性折射度比值Kr,阐述了Ka和Kr的物理意义.确定了团簇W2Ag4S8(dppf)2的三阶极化率x(3).团簇化合物W2Ag4S8(dppf)2对脉宽为纳秒的激发脉冲限幅效果比较好.     

长共轭基团取代功能聚丙烯酸酯的制备及光限幅性能研究

设计合成了{4/-[N,N-二(丙烯酸乙酯基)胺基],4-(吡啶-4-乙烯基))偶氮苯(PAC),通过和甲基丙烯酸甲酯共聚,制备出溶解性能较好的聚丙烯酸酯功能高分子,利用FTIR、NMR、UV等对化合物的结构进行了表征.光限幅实验发现,合成的聚合物对脉宽8ns,波长532nm的激光呈现限幅作用,对聚合物的光限幅机理进行探讨,显示主要为反饱和吸收机理.     

尿烷取代聚二炔反饱和吸收光限幅特性的研究

聚合炔（ＰＤＡｓ）材料有较大的非线性光学效应，在全光设备中有较大的在应用本文分别研究了尿烷取聚二乙炔的增强吸收和粗糙界面的光限幅特性，并分析了共限幅机理，发现粗糙界面光限幅比增强吸收光限幅有更好的光限幅特征。     

聚合物光限幅材料的研究

随着现代激光技术和武器的快速发展,急需激光防护材料(光限幅材料)和设备来防护人眼和光学传感设备免受激光的破坏.由于高分子光限幅材料具有大的非线性光学性能、快速的光学响应、高的损伤阈值和好的加工性能引起人们的广泛兴趣. 在这篇论文中,从分子结构以及分子结构对光限幅性能和光限幅机制的影响,对高分子光限幅材料进行了详细的综述,并提出高分子光限幅材料未来的发展方向.     

五氮齿金属配合物溶液对皮秒激光的光限幅

报导了五种五氮龄金属配合物对３５ｐｓ激光光限幅的实验结果,限幅机制属于激发态的反饱和吸收。在实验所用较高激光能量时,没有观察到样品被损坏的现象。配合物「（ＡＰＰＣ－ＣＯＯＨ）Ｃｄ」Ｃｌ（Ⅰ）和「ＡＰＰＣ－ＮＰ）Ｃｄ」Ｃｌ（Ⅱ）的光限幅阈值分别为４４．１ｍＪ／ｃｍ＾２和１４６ｍＪ／ｃｍ＾２,配合物Ⅰ最代非线性透过率达９％。吸电子基团能增强该类配合物对皮秒激光的限幅效果,而重原子效应则起相反的作用。     

2-炔丙基-4-[4-N,N-二乙基苯偶氮基]苯甲酸酯的合成、表征及光限幅性能

使用二环己基碳酰亚胺(DCC)和N,N-二甲基吡啶(DMAP)催化合成了非线性生色化合物2-炔丙基-4-[4-N,N-二乙基苯偶氮基]苯甲酸酯(PBAB)。与酸催化等法进行比较,DCC／DMAP催化法具有反应条件温和、产率高的优点。用紫外、红外、核磁和元素分析对化合物结构进行表征。测定了其光限幅性能,在低入射激光光强时,透射光强度随入射光强度增加而增加：当入射光强度达151．4GW／cm^2透射光强开始偏离线性,呈现非线性光限幅效应。对其限幅机制进行了分析,结果显示产物对1064nm波长激光的限幅机制主要是双光子吸收机制。     

非线性吸收激光光限幅材料研究进展

介绍了基于非线性吸收原理的新型光限幅材料及其研究进展。主要是反饱和吸收机制和双光子吸收机制的材料。     

掺Nd3+的镉硅酸盐玻璃的非线性光学特性

用高温熔融工艺制备了四种不同Nd3+掺杂浓度的镉铝硅酸盐玻璃样品,以纳秒Nd:YAG调Q激光器为光源,采用z-扫描技术研究了它们的非线性光学特性。结果表明,随着Nd3+浓度的增加,样品的非线性折射系数和非线性吸收系数也增加;光限幅测量表明,当入射功率密度大于118mW/mm2时,样品的透射功率密度与入射功率密度不再呈线性增加关系,而是随着入射功率密度的增加,透过率逐渐降低,透射功率密度增加缓慢,随着Nd3+浓度的增加,其光限幅效应显著增强。分析表明其光限幅效应是由反饱和吸收过程所致。     

Study of the nonlinear optical properties and behavior in phenoxy-phthalocyanines liquid at nanosecond laser pulses

The nonlinear optical properties of 2,9,16,23-phenoxy-phthalocyanine (Pc1) and 2,9,16,23-phenoxy-phthalocyanine-zinc (Pc2) in solution were investigated under excitation with nanosecond laser pulses at 532 nm. Based on five-level model, the nonlinear absorption in nanosecond regime was theoretically analyzed. The A-OS and OL behavior of Pc1 and Pc2 were further investigated with the pump–probe technique and transmission measurement technique. The results show that the A-OS response time is determined by the lifetime of the first triplet excited state of molecule, and Pc1 and Pc2 exhibit strong optical limiting effect at nanosecond laser pulses. These studies make the samples a promising possibility for device realization.     

Tunable emission and excited state absorption induced optical limiting in Tb2(MoO4)3: Sm3+/Eu3+ nanophosphors

Photoluminescence properties and optical limiting behavior of pure and Sm³⁺/Eu³⁺ doped Tb₂(MoO₄)₃ nanophosphors are investigated. The prepared nanophosphors exhibit excellent emission when excited by UV light. Color-tunable emissions in Tb_2−xSm_x(MoO₄)₃ and Tb_2−xEu_x(MoO₄)₃ are realized by employing different excitation wavelengths or by controlling the doping concentration of Sm³⁺ and Eu³⁺. Luminescence quantum yield and CIE chromatic coordinates of the prepared phosphors were also presented. Optical limiting properties of the samples are investigated by open aperture Z-scan technique using 5 ns laser pulses at 532 nm. Numerical fitting of the measured Z-scan data to the relevant nonlinear transmission equations reveals that the nonlinear absorption is arising from strong excited state absorption, along with weak absorption saturation and it is found that the optical nonlinearity of Tb₂(MoO₄)₃ increases with Sm³⁺/Eu³⁺doping. Parameters such as saturation fluence, excited state absorption cross section and ground state absorption cross section of the samples have been determined numerically, from which the figure of merit for nonlinear absorption is calculated. The excited state absorption cross-section of the samples is found to be one order of magnitude higher than that of the ground state absorption cross-section, indicating strong reverse saturable absorption. These results indicate that Sm³⁺/Eu³⁺ doped Tb₂(MoO₄)₃ nanophosphors are efficient media for UV/n-UV pumped LEDs, and are also potential candidates for designing efficient optical limiting devices for the protection of human eyes and sensitive optical detectors from harmful laser radiation.     

Graphene and its derivatives for laser protection

The development of functional materials for laser protection is an extremely important research field for the safety and security of users. To achieve simultaneous protection against both pulsed and continuous wave (cw) or quasi-cw lasers, significant research effort has been invested into state-of-the-art broadband optical limiting (OL) materials and processes in an attempt to achieve some measure of protection from such laser beams in the past decades. As the first truly two-dimensional material, graphene is being considered as an ideal material for modern photonic, optoelectronic and electronic devices because of its fantastic physical properties. Graphene shows ultrafast carrier relaxation dynamics and ultra-broadband resonate nonlinear optical (NLO) response due to their extended π-conjugate system and the linear dispersion relation holding for their electronic band structure. Almost all types of graphene-based materials described in this review exhibit strong broadband OL response. The dominant limiting mechanism of graphene is nonlinear scattering, which is very effective in liquid suspensions rather than in solid state hosts. In contrast to the pure graphene, the solubilized graphene and its derivatives optically limits through nonlinear absorption mechanism, nonlinear scattering as well as the photoinduced electron transfer and/or energy transfer between graphene and organic/polymeric species. This review describes systematically the OL mechanisms and the recent achievements on the graphene-based functional materials (i.e., graphene nanostructures, graphene composites, and covalently modified graphene) for OL applications. The future major ongoing areas of effort have also been suggested.     

Molecular Engineering of Peripherally And Axially Modified Phthalocyanines for Optical Limiting and Nonlinear Optics

Phthalocyanines have remarkable chemical and thermal stability and offer tremendous architectural flexibility in their structure, facilitating the tailoring of physical, optoelectronic, and chemical parameters. In this paper, we summarize experimental measurements of nonlinear optical absorption in a comprehensive representative series of modified phthalocyanines substituted with various central metals and peripheral functional groups. Rate equations are used to analytically solve the static‐state conditions that simulate the excited‐state dynamics that result from the nonlinear excited‐state absorption, and this solution is fitted to the experimental data. General molecular engineering trends relating the optical limiting performance of these compounds to their structural characteristics are also explored and discussed.     

Effect of electron acceptor type on nonlinear optical absorption properties in the chiral polymers based on polybinaphthyls

Nonlinear optical absorption properties of two chiral polybinaphthyls with the same backbone but different electron acceptor hydroxyl and octoxy were studied in tetrahydrofuran solution. When excited by 100 fs 800 nm laser pulses, the up-converted fluorescence were observed and the intensities related to the different input irradiances were measured to confirm the two-photon excited fluorescence. The two-photon absorption coefficients were obtained as 4.82 cm GW⁻¹ and 12.36 cm GW⁻¹ with 100 fs pulses at 800 nm for two polymers, respectively. Under the excitation of 532 nm 38 ps pulse, it was found that the polymer with the side-chain of hydroxyl showed saturable absorption while the polymer with the side-chain of octoxy presented reverse saturable absorption. Their different nonlinear absorption behavior resulted from the fact that the ground-state absorption cross-section in the latter polymer was about 10 times larger than that of the former polymer while the excited-state absorption cross-section represented similar.     

Studies on the two-photon pumped upconverted fluorescence and superradiance of a new organic dye material in solutions

The linear and nonlinear optical properties of a new organic dye, trans-4-[p-(N-ethyl-N-ethylamino)-styryl]-N-methyl-pyridinium tris(thiocyanato) cadmates (II), are reported in this paper. When pumped with a picosecond laser at the wavelength range of 850-1200 nm, intense upconversion fluorescence can be obtained. The upconversion efficiencies at different pump energies were measured when pumped with a 1064-nm laser beam from a mode-locked Nd:YAG laser. The highest upconversion efficiencies were measured to be 5.8% and 7.6% in dimethyl formamide (DMF) and methanol. The lifetime of the dye in DMF was measured to be 75 ps. The strongest nonlinear absorption was at the wavelength of 940 nm, and the highest upconversion efficiency was at the wavelength of 1030 nm. The difference of the two wavelengths was caused by excited state absorption in the dye at wavelengths shorter than 1000 nm. The dye solution in DMF and methanol show a clear optical power limiting effect.     

Indium(III) and Gallium(III) phthalocyanines-based nanohybrid materials for optical limiting

Linear and nonlinear optical properties of a phthalocyanine (Pc)-based nanohybrid material PCIGS [Cu₂(tBu₄PcGa)(tBu₄PcIn)S₂TPP₂] are described. The overall aggregation of phthalocyanines in poly(methylmethacrylate) (PMMA) films was evident, which is indicated by the broadening of linear spectra in the Q-band region and the shift of wavelength. Upon excitation with nanosecond laser pulse at 355 nm, the transient absorption band appeared at about 500 nm is attributed to the triplet–triplet absorption of the Pcs. For PCIGS and its starting materials tBu₄PcGaCl and tBu₄PcInCl, all Z-scans exhibit a decrease in transmittance about the focus typical of an induced positive nonlinear absorption of incident light. The absorption mechanism is due to population of excited states through a multi-step nonlinear absorption. When these Pc compounds were embedded into a commercially available polymer PMMA, all the Pc/PMMA composites display much larger nonlinear absorption coefficient and lower saturable fluence for optical limiting when compared to the same Pc molecules in solution. However, in contrast to tBu₄PcGaCl and tBu₄PcInCl, PCIGS displayed decreased optical limiting response, possibly due to competing electron accepting processes in the In and Ga metals, and the highly ordered structure of the PCIGS complex itself.     

Optical nonlinearity and optical limiting of CdSeS/ZnS quantum dots

CdSeS/ZnS quantum dots (QDs) were synthesized through the chemical route. The optical limiting behavior of these QDs was observed. The quantum dots’ nonlinear absorption and nonlinear refraction were investigated by the Z-scan technique using a Nd:YAG laser second-harmonic radiation (λ = 532 nm, t = 35 ps). Based on the absorption and fluorescence spectra, it is reasonable for us to infer that the nonlinear absorption arises from free carrier absorption (FCA). These QDs have average absorption cross-section of 1.26 × 10^?16cm² and nonlinear refractive index in the order of 10^?8esu. The large nonlinear absorption perhaps allows them to be candidate material for the optical limiting devices.     

Carbon nanotube-based functional materials for optical limiting

Optical limiting is an important application of nonlinear optics, useful for the protection of human eyes, optical elements, and optical sensors from intense laser pulses. An optical limiter is such a device that strongly attenuates high intensity light and potentially damaging light such as focused laser beams, whilst allowing for the high transmission of ambient light. Optical limiting properties of carbon nanotube suspensions, solubilized carbon nanotubes, small molecules doped carbon nanotubes and polymer/carbon nanotube composites have been reviewed. The optical limiting responses of carbon nanotube suspensions are shown to be dominated by nonlinear scattering as a result of thermally induced solvent-bubble formation and sublimation of the nanotubes, while the solubilized carbon nanotubes optically limit through nonlinear absorption mechanism and exhibit significant solution-concentration-dependent optical limiting responses. In the former case the optical limiting results are independent of nanotube concentrations at the same linear transmittance as that of the solubilized systems. Many efforts have been invested into the research of polymer/carbon nanotube composites in an attempt to allow for the fabrication of films required for the use of nanotubes in a real optical limiting application. The higher carbon nanotube content samples block the incident light more effectively at higher incident energy densities or intensities. The optical limiting mechanism of these composite materials is quite complicated. Besides nonlinear scattering contribution to the optical limiting, there may also be other contributions e.g., nonlinear absorption, nonlinear refraction, electronic absorption and others to the optical limiting. Further improvements in the optical limiting efficiency of the composites and in the dispersion and alignment properties of carbon nanotubes in the polymer matrix could be realized by variation of both nanostructured guest and polymer host, and by ex situ alignment and other methods. It would be very desirable, from the practical application point of view, if one can design broadband optical limiting chromophores that would function in a multimechanistic fashion.