共轭聚合物聚苯胺三阶非线性的研究进展

有机非线性光学材料因其优良的性能而引起广泛关注,共轭聚合物聚苯胺(PANI)的研究引起了人们的极大兴趣,文章综述了近年来聚苯胺及其衍生物三阶光学非线性的研究进展。     

共轭有机高聚物PPQ薄膜非线性吸收的Z-扫描测量

用 Z-扫描方法在 532 nm波长测量了共轭高聚物 PPQ( polyphenylquinoxalines)薄膜的三阶光学非线性参数 ,发现其较强的非线性 (双光子 )吸收系数β≈ 0 .59cm/ MW。同时得到 Kerr系数n2 ≈ 9.5× 10 -10 esu,与用其他方法的测量结果较好地吻合。     

Role of Dimensionality on the Two‐Photon Absorption Response of Conjugated Molecules: The Case of Octupolar Compounds

A comparative study of the two‐photon absorption (TPA) properties of octupolar compounds and their dipolar one‐dimensional counterparts is presented on the basis of correlated quantum‐chemical calculations. The roles of dimensionality and symmetry are first discussed on the basis of a simple exciton picture where the ground‐state and excited‐state wavefunctions of three‐arm octupolar systems are built from a linear combination of the corresponding single‐arm wavefunctions. This model predicts a factor of 3 increase in the TPA cross section in the limiting case of three independent charge‐transfer pathways. When taking into account the full chemical structures of representative octupolar molecules, the results of the calculations indicate that a much larger enhancement associated with an increase in dimensionality and delocalization can be achieved when the core of the chromophore allows significant electronic coupling among the individual arms. These theoretical predictions are in agreement with the experimental determination of the TPA cross sections for crystal violet and the related compound, brilliant green, and suggest new strategies for the design of conjugated materials with large TPA cross sections.     

大带宽集成光学电场传感器的频率响应特性分析

采用马赫-曾德尔光波导干涉仪与锥形天线阵列,研制了基于铌酸锂（LiNbO3）结构、可用于电力电场测量的大带宽电场传感器,并通过实验对传感器性能进行了测试。结果表明,该传感器在10kHz～18GHz的大带宽范围内,频响特性波动小于±10dB,最小可测电场强度达到0.4V/m,可测量场强达103V/m的纳秒脉冲电场。     

双包层非线性单轴光纤传播常数的计算

基于严格的矢量波理论,用摄动法导出了计算双包层非线性单轴光纤导模或泄漏模传播常数的公式。     

外电场作用下InP电子结构与光学性质的计算

磷化铟(InP)已成为光电器件和微电子器件不可或缺的重要半导体材料。采用基于密度泛函理论框架下的第一性原理平面波赝势方法,计算了不同外电场作用下InP超胞的电子结构和光学性质。计算结果表明:未加电场时InP的能隙值为0.876eV,随着z轴方向的外电场增大,该值逐渐减小,当电场强度达到1.0×10⁸V/cm时,InP的禁带宽度几乎为0。InP导带区域的总态密度随着外电场增大逐渐向费米面偏移,态密度跨度变小,而价带与导带的情况恰恰相反。外电场对介电函数虚部的影响主要体现在低能量区域(0~7eV),而在较高能量区域内可忽略不计。外电场对InP吸收系数的影响主要集中在近红外波段。     

Advanced Ellipsometric Characterization of Conjugated Polymer Films

Conjugated polymers are attracting worldwide attention due to their potential for use as the active layer in advanced electronic, optoelectronic, and energy harvesting applications, and their cost‐effective and low thermal budget processing traits. As the technologies based on these materials develop, new and more sensitive characterization techniques are needed. Recent progress on the use of spectroscopic ellipsometry as a highly sensitive and non‐invasive method to obtain fundamental information about conjugated polymer films is reviewed. After a brief introduction to the practical details of the technique, the use of ellipsometry to determine optical parameters that provide insight into film morphology is described, including physical phase and molecular orientation, and resulting electronic structure. The characterization of layered systems and the use of in‐situ ellipsometry as a means to gain understanding of the kinetics that occur during film deposition and post‐deposition thermal and solvent vapor treatment is also discussed.     

Linear and Nonlinear Optical Properties of Ag Nanowire Polarizing Glass

An R₂O–B₂O₃–SiO₂ (R = Li, Na, K) polarizing glass containing Ag nanorods is prepared by thermal elongation–reduction technology. The transverse and longitudinal plasmon absorption peaks of the embedded Ag nanorods are near 460 and 720 nm, respectively. When the polarization of the laser is parallel to the long axis of the Ag nanorods, the nonlinear absorption coefficient β = 0.82 cm GW^–1 and the nonlinear refractive index n₂ = –1.5 × 10^–4 cm² GW^–1. When the polarization of light is perpendicular to the long axis of the Ag nanorods β = 0.12 cm GW^–1 and n₂ = –7.2 × 10^–5 cm² GW^–1 and the appropriate one‐ and two‐photon figures of merit (FOM), W = 1.6 and T = 0.16, respectively, are obtained, which satisfies the demand, W > 1 and T < 1, for applications in all optical switching, where W is a one‐photon FOM, and T is a two‐photon FOM.     

Synthesis,Characterization, and Nonlinear Optical Study of Metalloporphyrins

meso‐Tetrakis{4‐[2‐(trimethylsilyl)ethynyl]phenyl}porphyrin [TPP(4‐CCTMS)_H2] and its complexes with Zn^II, Ni^II, Ga^III, In^III, and Sn^IV were synthesized and characterized. Their nonlinear optical transmission characteristics were determined using a 532 nm, 5 ns pulsed laser at a repetition rate of 20 Hz. Stronger nonlinear absorption was obtained with the zinc derivative, Zn^II‐meso‐tetrakis{4‐[2‐(trimethylsilyl)ethynyl]phenyl}porphyrin (TPP(4‐CCTMS)_Zn), than with the standard analogues, Zn^II‐meso‐tetraphenylporphyrin (TPP_Zn), and Zn^II‐meso‐tetratolyl‐porphyrin (TTP_Zn), indicating that the excited‐state absorption can be influenced via fine molecular modification on the para‐position of the meso‐phenyl rings, without changing the ground‐state absorption. The nonlinear optical response can be further enhanced via insertion of closed‐shell metal ions. In particular, In^IIICl‐meso‐tetrakis{4‐[2‐(trimethylsilyl)ethynyl]phenyl}porphyrin (TPP(4‐CCTMS)_InCl), exhibited a larger change in transmission with increasing energy than C₆₀ and a comparable change to the state‐of‐the‐art phthalocyanine dye, chloro(tetra(tert‐butyl)phthalocyanato)indium(III) (Pc(t‐Bu)_InCl).     

New Organic Nonlinear Optical Polyene Crystals and Their Unusual Phase Transitions

A series of new nonlinear optical chromophores based on configurationally locked polyenes (CLPs) with chiral pyrrolidine donors are synthesized. All CLP derivatives exhibit high thermal stability with decomposition temperatures T_d at least > 270 °C. Acentric single crystals of enantiopure D ‐ and L ‐prolinol‐based chromophores with a monoclinic space group P2₁ exhibit a macroscopic second‐order nonlinearity that is twice as large than that of analogous dimethylamino‐based crystal. This is attributed to a strong hydrogen‐bonded polar polymer‐like chain built by these molecules, which is aligned along the polar crystallographic b‐axis. Five α‐phase CLP crystals with different donors grown from solution exhibit a reversible or irreversible thermally induced structural phase transition to a β‐phase. These phase transitions are unusual, changing the crystal symmetry from higher to lower at increasing temperatures, for example, from centrosymmetric to non‐centrosymmetric, enhancing their macroscopic second‐order nonlinear optical properties.     

InAs/InP Self‐Assembled Quantum Dots: Wavelength Tuning and Optical Nonlinearities

Quantum dots (QDs, i.e., semiconductor nanocrystals) can be formed by spontaneous self‐assembly during epitaxial growth of lattice‐mismatched semiconductor systems. InAs QDs embedded in GaInAsP on InP are introduced, which can be continuously wavelength‐tuned over the 1.55 μm region by inserting ultrathin GaAs or GaP interlayers below them. We subsequently introduce a state‐filling optical nonlinearity, which only requires two electron–hole pairs per QD. We employ this nonlinearity for all‐optical switching using a Mach–Zehnder interferometric switch. We find a switching energy as low as 6 fJ.     

The Singlet–Triplet Exchange Energy in Conjugated Polymers

Electron–electron interactions in organic semiconductors split the lowest singlet and triplet states by the exchange energy, ΔE_ST. Measurement of singlet and triplet emission spectra in a large number of conjugated polymers yield an almost constant ΔE_ST value close to 0.7 eV. This is in contrast to the situation in molecules, where the exchange energy is found to depend on molecular size and to vary over a wide range. Quantum‐chemical calculations are performed to address the origin of the constant exchange energy in phenylene‐based conjugated polymers. The electron–hole separation in the lowest singlet and triplet excited states is found to be independent of the π‐conjugated backbone, and saturates for chains longer than a few repeating units, resulting in a constant exchange energy. In shorter conjugated oligomers, confinement of the excitations destabilizes the singlet with respect to the triplet through exchange interactions and leads to a larger and size‐dependent singlet–triplet energy separation.     

Synthesis and Spectral and Structural Elucidation of Some Pyridinium Betaines of Squaric Acid: Potential Materials for Nonlinear Optical Applications

A series of substituted pyridinium betaines of squaric acid have been prepared by quaternization reaction of 3‐ and 4‐substituted pyridines with squaric acid. The products were characterized by means of elemental analysis, melting points, and their UV‐vis and IR spectra. The UV‐vis spectra of all investigated compounds in five different solvents were studied in detail. The UV‐vis spectral elucidation has given evidence of the clearly distinct negative solvatochromism of the pyridinium betaines of squaric acid, characteristic for compounds with a dipolar electronic ground state structure. The two absorption bands observed in the visible region show a charge‐transfer character, which determines their strong dependence on the polarity of the medium and the nature of the substituent. The investigation of the spectral behavior of pyridinium betaines of squaric acid has revealed their potential nonlinear optical and electro‐optical properties. Furthermore, these compounds exhibit remarkable thermal stability, required for such applications. The eventual technical application of these colored single crystals is discussed.     

Response of the Internal Electric Field in CdZnTe to Illumination at Multiple Optical Powers

Manipulation of CdZnTe (CZT) crystals using illumination is a useful tool for altering the internal electric field present under normal bias conditions. The interactions with carriers that are trapped at either terminal are visualized by the electric field distribution through polarization. In this report, we demonstrate an ability to selectively manipulate the internal electric field of CZT using multiple-wavelength light illumination at various optical powers. The internal electric field polarization can be controlled using changes in optical power. We also investigate the electric field distributions using multiple optical powers to examine the light response as a function of light penetration depth.     

光场与掺杂向列相液晶薄膜相互作用的若干问题

从激光与掺杂液晶薄膜相互作用的角度，介绍了掺杂液晶非线性光学的多个不同侧面，阐述了光场诱导液晶分子指向矢的重新取向问题、偶氮物掺杂液晶超大光学非线性问题、以及掺杂液晶光限幅的研究现状和进展。     

吡啶盐衍生物分子非线性光学性质的理论研究

采用从头算HF/6-31G(d)方法优化吡啶盐衍生物分子,在优化构型的基础上,采用耦合微扰Hartree-Fock(CPHF)方法研究体系的非线性光学性质。通过对体系的电荷分布、前线分子轨道以及吸收光谱等性质的分析,发现给体的给电子能力与跃迁偶极矩以及基态和激发态之间的偶极矩差成正比关系,由二能级公式得到给体的给电子能力与静态一阶超极化率成正比关系。采用单激发组态相互作用方法(CIS)方法研究体系的激发态情况,发现给体的给电子能力和分子平面性共同决定激发能的大小。     

群速度色散对非线性光纤环镜型OTDM解复用器影响的理论与数值分析

本文就群速度色散对非线性光纤环镜型ＯＴＤＭ解复用器的影响进行了理论与数值分析．首先给出了描述群速度色散与非线性效应之间相互作用的耦合非线性薛定谔方程组,然后用分步傅立叶方法对该方程组进行了数值求解．经分析指出,要达到一定的开关性能,孤子阶数、色散的正负、脉冲宽度及控制和信号脉冲之间的走离时间应满足一定的条件．     

Thermal and Transmission Properties of UV Nonlinear Optical Material—ZnCd（SCN）4 Crystal

Zinc cadmium thiocyanate(ZCTC),ZnCd(SCN)4, has been discovered as a UV second-order nonlinear optical coorination crystal.Its thermal and transmission properties are reported.The thermal decomposition is characterized by using the X-ray powder diffraction (XRPD) and infared (IR) spectroscopy at roon temperature.The absorptions of intrinsic ions and ZCTC in a solution state are discussed as well as transmission properties of the ZCTC crystal.An effective method of reducing the surface reflection loss of ZCTC crystal is introduced.     

π共轭聚吡咯衍生物非线性响应时间的测量

合成一种新型π共轭聚吡咯衍生物———聚吡咯 { 2 ,5 二 [(对硝基 )苯甲烯 ]} (PPNB) ,制备了该高分子的N 甲基 2 吡咯烷酮 (NMP)溶液和聚乙烯醇 (PVA)复合薄膜。用 5 32nm ,8ns脉冲激光作抽运光源 ,氦氖激光 (6 32 8nm ,CW)为探测光源 ,测量了该高分子的非线性光学响应过程 ,测得PPNB/NMP溶液和PPNB/PVA薄膜的激光诱导折射率的建立时间分别为 4μs和 5 μs,恢复时间分别为 30ms和 5ms。引起这种非线性效应的机制可能主要是热光非线性效应。