用飞秒Ti：sapphire激光测定对称型化合物的双光子吸收和上转换荧光

用800nm波长的飞秒Ti:sapphire激光测定了2个对称型噁二唑衍生物2,5-二[4-(2-N,N-二苯氨基苯乙烯基)苯基]-1,3,4-噁二唑(PASPO)与2,5-二[4-{2-N,N-二(4-溴代苯)氨基苯乙烯基]苯基}-1,3,4-噁二唑(BrPASPO)的双光子吸收和双光子激发荧光光谱,其飞秒双光子吸收截面为20.6和9.91GM,双光子泵浦上转换荧光最大波长分别在535和545nm.测定了紫外吸收、荧光光谱,研究了化合物在不同溶剂中的溶致变色效应.化合物PASPO和Br-PASPO在二氯甲烷溶液中的吸收峰分别位于412和403nm,荧光发射峰分别位于511和495nm,荧光量子产率分别为0.73和0.70.     

立方硅氧烷多枝分子合成与双光子吸收性能研究

以自制立方硅氧烷(OPS)为"核",合成4种立方硅氧烷多枝分子实现了有机/无机分子杂化.在800nm Ti蓝宝石激光器泵浦下开孔z扫描技术测得多枝分子sample 3、4具有明显的双光子吸收,吸收系数分别为1.4×10-11和2.0×10-11 cm/W;CCD光谱仪记录到两样品的上转换荧光峰位在600nm左右.经过立方硅氧烷杂化的多枝分子热分解温度最高可达377℃.     

一种三取代结构双光子吸收材料的合成

合成了一种新型三取代结构的双光子吸收材料1,3,5-三[4-[2-(3-吡啶)乙烯基]苯基]苯(4),通过元素分析、电喷雾质谱、1HNMR和红外对其进行表征。测试了紫外吸收光谱、单光子荧光光谱和双光子荧光光谱,并测出其双光子吸收截面为7.63×10-48cm4.s.photon-1。利用合成的1,3,5-三[4-[2-(3-吡啶)乙烯基]苯基]苯作引发剂,以甲基丙烯酸甲酯齐聚物作单体(CN120C80),200fs,76MHz、Ti∶sapphire飞秒激光器作光源,进行了三维周期微结构的制作。所合成化合物是潜在应用前景的双光子吸收材料。     

Er3+单掺与Er3+/Yb3+共掺Y2SiO5的上转换发光

报道了一种新的上转换发光材料X2型Y2SiO5:Er, Yb并研究了Yb3 浓度和泵浦功率对样品的上转换发光特性的影响:(1)随着Yb3 浓度的增加,绿、红光发射均呈先增强后减弱的变化,但相对于绿光发射,红光发射受Yb3 浓度的影响更剧烈,并且当12%(摩尔分数)Yb3 时,可以得到很纯的红光发射;(2)上转换发光强度与泵浦功率的关系表明,双光子吸收贡献样品的上转换发射.此外,讨论了可能的上转换机制.认为随着Yb3 浓度增加,Er3 的激发态吸收、Yb3 到Er3 的能量传递和Er3 的交叉弛豫对上转换发光的作用依次逐渐加强.     

一种基于光敏半导体的多功能交叉沙漏型超表面

提出一种基于光敏半导体的多功能超表面,该超表面具有双峰吸收、宽频和双频极化转换3种模式.在没有泵浦光照射时,超表面工作在双峰吸收模式,在2.25 THz和2.75 THz两个峰处的吸收率分别为95.1%和94.4%;当超表面处于1 550 nm泵浦光照射条件下,可工作在宽频极化转换模式,在1.32 THz～2.15 THz频段的极化转换率达到90%以上,相对带宽为47.8%;当超表面处于800 nm泵浦光照射条件下,超表面工作于双频极化转换模式,在1.09 THz～1.23 THz和2.12 THz～2.23 THz两个频段的极化转换率均超过90%.此外,通过分析磁场和表面电流分布,解释了不同工作模式的物理机制.本文所提出的超表面有望应用于未来的多功能太赫兹设备.     

含杂芴与噁二唑分子的p-n结与分子双光子吸收性能关系的研究

研究了若干个含杂芴与噁二唑分子的线性和非线性光谱性能.分别在飞秒钛宝石激光器泵浦下,通过开孔Z-scan技术和双光子荧光法研究了分子的双光子吸收性能;结合理论计算考察分子基态与激发态分子内电荷转移、分子p-n结对双光子吸收的影响.     

强双光子吸收化合物NT-G1和NO-G1合成与性能研究

选择氮杂芴(咔唑)为π中心,分别以三苯胺和二唑取代基为“枝”,合成了两个强双光子吸收的氮杂芴衍生物2,8 双(4 三苯胺乙烯基) N 乙基氮杂芴(简称NT G1)和2,8 双(2 (4’乙氧基) 5 (4’苯乙烯) 1,3,4 二唑) N 基氮杂芴(简称NO G1),进行了核磁共振谱和质谱等表征。飞秒钛宝石激光器泵浦下,NT G1 和NO G1 溶液发出强双光子上转换荧光,且后者的双光子荧光发射截面是前者的7倍;双光子荧光法计算出NT G1 和NO G1 双光子吸收截面分别为215GM和454GM。分子构型优化表明,NT G1分子中心“氮杂芴”所在平面与两端苯环呈螺旋桨式排布;而NO G1 分子共轭长度增大,且中心的“氮杂芴”与两端延伸的“枝”呈平面构型;从结构上看,NO G1分子属“D A πA D”型,具有明显的pn 结模式,这些都使NO G1 分子具有更好的分子内电荷转移能力,因而有较高的双光子吸收截面。     

Er~(3+)/Yb~(3+)共掺SrF_2纳米晶的溶剂热合成及发光性能研究

采用溶剂热方法制备得到了Er3+和Yb3+共掺杂的SrF2纳米晶,并对其上转换发光性能进行了研究.X-射线衍射结果表明所制备的产物为纯的SrF2.随着溶剂热温度的升高,该纳米晶衍射峰的强度逐渐增强,且与SrF2的标准衍射峰相比,所有衍射峰均向高角度偏移.TEM的结果表明,溶剂热处理后,SrF2颗粒的分散性得到明显改善,且晶粒大小随着溶剂热温度的升高而增大.在980nm激光泵浦下Er3+和Yb3+共掺杂SrF2纳米晶仅能观察到弱的上转换发光,而在500℃和600℃热处理2h后,其上转换发光强度明显增强.上转换发光强度与泵浦功率的关系表明绿光和红光均为双光子吸收过程.     

一种共轭有机杂环分子的双光子吸收与电化学性质

实验研究了一种新的共轭杂环化合物9-乙基-3-{5-(4-叔丁基苯基)-[1,3,4]-噁二唑-2-苯乙烯基}-咔唑(VBPOEC)的双光子吸收性质和电化学性质.双光子吸收截面采用非线性透过率法测定,双光子最大吸收波长位于800nm,吸收截面为1350GM.采用紫外光谱的边带吸收法得到带隙为2.77eV,用循环伏安法对其电化学性质进行了初步研究,氧化电位为1.059V,其HOMO能级为-5.80eV,其LUMO轨道能级为-3.03eV.研究了光学、电化学性质与分子电子结构的关系.     

Ho3+掺杂浓度对氟化镓铟玻璃上转换发光性质的影响

本文制备了掺不同浓度Ho^3＋氟化镓铟玻璃为基质的上转换发光材料20GaF3-15InF3-20CdF2-15ZnF2-（20-x）PbF2-10SnF2-xHoF3（x=0.1,0.3,0.5,1.0,1.5,2.0）,通过对样品的吸收、发射光谱和发光衰减过程的研究,认为在643nm激发下,^5G5→^5I8（422nm）、^5F3→^5I8（480nm）和^5S2→^5I8（520nm）三个发光为双光子上转换发光.在726nm激发下,^5F3→^5I8（483nm）和^5F4（^5S2）→^5I8（540nm）为上转换发光,其中483nm属于双光子过程,540nm是雪崩上转换.     

Two-photon pumped upconversion and nonlinear optical properties of a new lasing dye: HMASPS

Abstract

Two-photon pumped frequency upconversion optical properties and two-photon absorption (TPA) induced nonlinear absorption of a new dye, trans-4-[p-(N-hydroxyethyl-N-methylamino)styryl]-N-methylpyridinium ptoluene sulfonate (abbreviated to HMASPS) have been experimentally investigated. This new dye exhibits strong superradiation properties when the pumping power is above its threshold. The superradiation upconversion efficiency from 900 to 1150 nm and the nonlinear absorption from 720 to 1100 nm have been measured. The largest effective molecular TPA cross-section was measured to be 44.3 × 10^?48 cm⁴·s·photon^?1at 920 nm. At 1064 nm, it was 2.77 × 10^?48 cm⁴·s·photon^?1, much smaller than that at 920 nm. The highest conversion efficiency is 7% at 990 nm, whereas 4.2% at 1064 nm.     

Studies on two-photon pumped frequency up-converted lasing properties of a new material HMASPS

Abstract

A new dye trans-4-[p-(N-hydroxyethyl-N-methylamino)styryl]-N-methylpyridinium p-toluene sulphonate (abbreviated as HMASPS) was synthesized, the two-photon absorption (TPA), TPA-induced frequency up-conversion emission, and two-photon pumped (TPP) frequency up-converted lasing properties of HMASPS were experimentally studied. This new dye has a moderate TPA cross-section of σ₂ = 6.0 × 10^?48 cm⁴ s photon^?1, but exhibits a high lasing efficiency. The net conversion efficiency from the absorbed 1064 nm pump pulse energy to the 630 nm up-converted lasing energy is 4% at a pump energy level of 4mJ.     

Optical properties of a new two-photon absorbing chromophore

A new dye, trans-4-[p-(pyrrolidinyl)styryl]-N-methylpyridinium iodide, has been synthesized, and the two-photon-absorption (TPA), TPA-induced frequency upconversion emission, and two-photon-pumped (TPP) frequency upconverted lasing properties of this new dye were experimentally studied. This new dye has a moderate TPA cross section of varsigma(2) = 5.7 x 10(-48) (cm(4) s(-1))/photon at 1064 nm but exhibits high lasing efficiency. The slope efficiency of the TPP cavity laser with this new dye as the laser medium is 1.6%.     

Two-photon Absorption and Nonlinear Optical Properties of A New Organic Dye DEASPI

A new organic dye trans-4- [p-(N,N-diethylamino) styryl]-N-methylpyridinium iodide (abbreviated' as DEASPI thereafter) with large two-photon absorption (TPA) cross section and excellent upconverted lasing properties was synthesized. The melting point and decompound point were measured to be 230 degreesC and 264.7 degreesC respectively. The molecular TPA cross section was measured to be sigma (2)=6.9x10(-48) cm(4).s/photon at 1064 nm by using an open aperture Z-scan system. The linear and nonlinear optical properties of this dye were systematically studied. The highest net upconversion efficiency from the absorbed pump energy to the output upconverted lasing energy is as high as 18.6% at the pump energy of 2.17 mJ from a mode-locked Nd:YAG ps laser. The nonlinear transmittance at the wavelengths from 720 to 1100 nm was measured. The dye solution also shows a clear optical power limiting effect.     

Upconversion fluorescence and optical power limiting effects based on the two- and three-photon absorption process of a new organic dye BPAS

A new organic dye, trans-4, 4'-bis(pyrrolidingl) stilbene (BPAS), with large two-photon absorption (TPA) and three-photon absorption (3PA) has been synthesized. The molecular TPA cross section sigma2' at 550-670 nm and the 3PA cross section sigma3' at 720-1000 nm have been measured. The biggest sigma2' and sigma3' was 5.77 x 10(-47) cm4s/photon and 27 x 10(-75) cm6 s2 at 600 and 980 nm, respectively. In the experiment process we found that the strongest TPA wavelength is not at two times of the strongest linear absorption wavelength, but there is some blue shift. The 3PA-induced optical power-limiting properties have also been illustrated at 980 nm.     

Limited efficiency of a silver selenogallate optical parametric oscillator caused by two-photon absorption

The nonresonant two-photon absorption (TPA) coefficient in silver selenogallate (AgGaSe(2)) crystals was measured for both ordinary and extraordinary polarizations in the 1300-1600-nm wavelength range. We found a cutoff wavelength for the TPA at between 1400 and 1500 nm, which corresponds to half of the bandgap energy of the AgGaSe(2) crystal. Below the cutoff wavelength we measured the TPA coefficient to be approximately 0.035 cm/MW for the extraordinary polarization and two to three times lower for the ordinary polarization. We compared the AgGaSe(2) samples from two manufacturers and observed a factor of 2 difference in the TPA coefficients. Because of the high TPA, the 1.32-mum pumped AgGaSe(2) optical parametric oscillator conversion efficiency was clipped at a low level.     

Synthesis and nonlinear optical properties of two new two-photon initiators: Triphenylamine derivatives

Two new two-photon polymerization initiators, 1-{(1E)-2-[4-(diphenylamino)phenyl]vinyl}-4-[4-N,N-di-methylamino]benzene (PVMB) and 1-[(1E)-2-(4-{[4-((1E)-2-{4-[4-N,N-di-methylamino]phenyl}vinyl)phenyl]phenylamino}phenyl)vinyl]-4-[4-N,N-di-methylamino]benzene (DPVMB) have been synthesized with solid phase Wittig reaction. The single-photon fluorescence, quantum yields, lifetimes, solvent effects of the initiators were studied in detail and both compounds exhibited solvent-sensitivity. Two compounds are good two-photon absorbing chromophores and operative two-photon photopolymerization initiators. Two-photon absorption (TPA) cross-sections from 730 nm to 870 nm at intervals of 10 nm have been measured with the two-photon-induced fluorescence method, and the maximal values of the TPA cross-sections of PVMB and DPVMB are 1.6 GM and 19.9 GM (1 GM = 1 × 10⁻⁵⁰ cm⁴ s photon⁻¹ molecule⁻¹) at 800 nm, respectively. A microstructure has been fabricated by using DPVMB as initiator.     

The theoretical investigation of the impact of two-photon absorption and free-carrier absorption on phase-sensitive amplification in silicon waveguides

We investigate the influence of two-photon absorption (TPA) and free-carrier absorption (FCA) on phase-sensitive amplification (PSA) process in a dispersion engineered silicon strip waveguide at the telecom wavelengths. The phase-dependent gain and phase-to-phase transfer functions as well as the phase regeneration capacity of PSA are numerically analysed. It is found that TPA and FCA will suppress the phase-sensitive extinction ratio (PER) and the efficiency of phase squeezing. Moreover, the phase regeneration capability of silicon waveguide-based PSA is investigated by comparing the regenerated signal waveforms at a different signal power with/without TPA and FCA. Our results have potential application in all-optical signal regeneration.     

The empirical correlation between size and two-photon absorption cross section of CdSe and CdTe quantum dots

The tuning of CdSe quantum dot (QDs) sizes, and consequently their corresponding two-photon absorption (TPA) cross section, has been systematically investigated. As the size (diameter) of the quantum dots increases, the TPA cross section is found to be empirically related via a power-law proportionality of 3.5+/-0.5 and 5.6+/-0.7 to the diameters of CdSe and CdTe QDs, respectively. The results are tentatively rationalized via a theoretical model of two-photon excitation properties in a system incorporating excitons and defects.     

Two-photon resonance-enhanced refractive-index change and self-focusing in a dye-solution-filled hollow fiber system

The general behavior of two-photon absorption-enhanced refractive-index change in a third-order nonlinear optical medium is briefly described. The nonlinear medium was the solution of a new dye, trans-4-[p-(N-hydroxyethyl-N-methylamino)styryl]-N-methyl pyridinium iodide (ASPI) in dimethyl sulfoxide as the solvent, that was poured into a 20-cm-long quartz hollow fiber of 100-mum internal diameter. This dye solution has a strong two-photon absorption and subsequent upconversion fluorescence emission when excited with 1064-nm laser radiation. When the input peak intensity reached 500-1500-MW/cm(2) levels, obvious changes in beam profiles of the output IR laser beam were observed due to a self-focusing or self-trapping process occurring inside the fiber system. As a result of this process, highly directional frequency-upconverted superradiant lasing output was obtained with a beam size ~5 times smaller than that of a linearly transmitted He-Ne probe laser beam. The demonstrated mechanism can be useful for fiber laser-amplifier and fiber-integrated optics devices.