Nonlinear Dispersion of Magnetostatic Surface Waves on Ferromagnetic Films

The wave equation of nonlinear magnetostatic surface waves (MSSW) on ferromagnetic films is derived and its solution is found. The nonlinear dispersion relation of MSSW in discussed. Our Result shows that the wave power has a little effect to the frequency shift of MSSW with lower frequency, but has a considerably larger effect to that with higher frequency within the band.     

Nonlinear Optical Response of nc-Si-SiO2 Films Studied with Femtosecond Four-Wave Mixing Technique

Nonlinear optical properties of silicon nanocrystals （nc-Si） embedded in SiO2 films are investigated using timeresolved four-wave mixing technique with a femtosecond laser. The off-resonant third-order nonlinear susceptibility X^（3） is observed to be 1.3×10^-10 esu at 800nm. The relaxation time of the film is fast as short as 50fs. The off-resonant nonlinearity is predominantly electronic in origin and enhanced due to quantum confinement.     

Heavy Ion Irradiated Ferromagnetic Films: The Cases of Cobalt and Iron

Polycrystalline, e-gun deposited Co, Fe and Co/Fe films, tens of nanometers thick, have been irradiated with Ne, Kr, Xe and/or Fe ions to fluences of up to 5 × 10¹⁶ ions/cm². Changes in the magnetic texture induced by the implanted ions have been measured by means of hyperfine methods, such as Magnetic Orientation Mössbauer Spectroscopy (Fe), and by Magneto-Optical Kerr Effect and Vibrating Sample Magnetometry. In Co and CoFe an hcp → fcc phase transition has been observed under the influence of Xe-ion implantation. For 10¹⁶ Xe-ions/cm², ion beam mixing in the Co/Fe system produces a soft magnetic material with uniaxial anisotropy. The effects have been correlated with changes in the microstructure as determined via X-ray diffraction. The influences of internal and external strain fields, an external magnetic field and pre-magnetization have been studied. A comprehensive understanding of the various effects and underlying physical reasons for the modifications appears to emerge from these investigations.     

Linear and Nonlinear Optical Characterization of PolyDCHD-HS Films

Waveguiding films of the highly soluble polycarbazolydiacetylene polyDCHD-HS were prepared by spin coating and characterized at different wavelengths: 5 dB/cm propagation losses were observed at 1321 nm.Measurements of the third order nonliearity at 1064nm with the surface plasmon resonance method gave the valueχ(3)= i4.4×10-17+3.5×10-18 m2/V2.     

Linear and Nonlinear Optical Characterization of PolyDCHD-HS Films

Waveguiding films of the highly soluble polycarbazolydiacetylene polyDCHD-HS were prepared by spin coating and characterized at different wavelengths: 5 dB/cm propagation losses were observed at 1321 nm.Measurements of the third order nonliearity at 1064nm with the surface plasmon resonance method gave the valueχ(3)= i4.4×10-17+3.5×10-18 m2/V2.     

Nonlinear Optical Response of a Fibonacci Multilayer

By studying numerically the light transmitting through a finite nonlinear Fibonacci multilayer, we find the gap-soliton-like phenomenon. The Fibonacci multilayer contains a Kerrtype nonlinearity in one component. When the frequency of incident light is in a stop gap, increasing the incident light intensity will make the system switch from a lower transmission state to a higher transmission state. Transmissivity for some frequencies can reach unit, which shows that they correspond to transparent states. Distribution of the field intensity in the Fibonacci structure has a particular gap-soliton-like shape, which has the multi-carrier wave.     

稀土夹心双酞菁铽LB膜非线性光学特性

利用π-A等温曲线和-二次谐波产生方法研究了稀土夹心双酞菁铽(TbPcPc*)分子在Langmuir膜及Langmuir Blodgett(LB)膜中分子的排列状态及其非线性光学特性,并对非线性产生机制进行了简单的讨论.实验结果表明,TbPcPc*分子在亚相表面可形成稳定的Langmuir膜,凡以edge-on构型面对面倾斜排列.其X型LB膜具有较好的二次谐波信号,二次谐波信号的最大值在基频光入射角为55°的地方.其._二阶非线性极化率γ(2)和分子超极化率β分别为1.64×10'-8esu和6.21×10-30esu.通过测量样品二次谐波信号的偏振特性,并与理论分析相比较,其二阶仆线性起源于电四极子和电偶极子机制.     

咔唑-苯并噻唑类衍生物薄膜的线性及非线性光学性质

以咔唑为电子供体,苯并噻唑为电子受体,合成了两种新型咔唑-苯并噻唑衍生物3-(2-苯并噻唑-2-基乙烯基)-N-乙基咔唑和3,6-二(2-苯并噻唑-2-基乙烯基)-N-乙基咔唑,通过核磁共振和分光光度计对其结构进行表征.利用刮刀法制备质量分数为4％的衍生物/聚酰亚胺的复合薄膜.采用透射光谱法和单光束Z-扫描技术分别测试了衍生物的线性和三阶非线性光学特性.Z扫描实验结果表明3-(2-苯并噻唑-2-基乙烯基)-N-乙基咔唑薄膜的非线性吸收系数和非线性折射系数分别为β1=-2.118 9×10-10 cm/W、r1=2.285 2×10-14 cm2/W,具有反饱和吸收特性和自聚焦效应;同时3,6-二(2-苯并噻唑-2-基乙烯基)-N-乙基咔唑薄膜的非线性吸收系数与非线性折射系数分别为β2=-1.275 6×10-9 cm/W、r2=-7.039 9×10-14 cm2/W,具有反饱和吸收特性和自散焦效应.     

Magnetization of Coupled Ultrathin Ferromagnetic Films

The magnetization of coupled ferromagnetic films is calculated by Green's function method. The coupling can either be ferromagnetic or antiferromagnetic. For the latter case, a concept of pseudo-spin is suggested to make calculation possible. A pseudo-spin is actually an anti-spin with its properties being analogue to other known anti-particles such as a hole. The decreasing of Curie point as the coupling strength decays is computed. It is noted that with the same strength, antiferromagnetic coupling has higher Curie point than ferromagnetic coupling.     

Z-扫描参量对薄膜材料三阶非线性光学特性的影响

采用数值计算方法对薄膜材料的Z-扫描参量进行研究.对不同激光脉宽下Z-扫描的三阶非线性折射系数和吸收系数进行分析,结果显示不同等级的脉宽激光器对计算结果的数量级影响很大.对不同小孔光阑半径的Z-扫描闭孔曲线进行仿真,结果显示光阑小孔越小,获得特征曲线的峰谷值越明显.对不同光阑离透镜焦点的距离值进行Z-扫描闭孔曲线仿真,结果显示距离为1/2透镜焦距值时闭孔Z-扫描曲线能得到相对较大的峰谷差值.数值分析结果与相关文献报道的实验结果基本一致.     

Magnetization of Coupled Ultrathin Ferromagnetic Films

The magnetization of coupled ferromagnetic films is calculated by Green‘s function method. The coupling can either be ferromagnetic or antiferromagnetic. For the latter case, a concept of pseudo-spin is suggested to make calculation possible. A pseudo-spin is actually an anti-spin with its properties being analogue to other known anti particles such as a hole. The decreasing of Curie point as the coupling strength decays is computed. It is noted that with the same strength, antiferromagnetic coupling has higher Curie point than ferromagnetic coupling.     

Z-扫描参量对薄膜材料三阶非线性光学特性的影响

采用数值计算方法对薄膜材料的Z-扫描参量进行研究.对不同激光脉宽下Z-扫描的三阶非线性折射系数和吸收系数进行分析,结果显示不同等级的脉宽激光器对计算结果的数量级影响很大.对不同小孔光阑半径的Z-扫描闭孔曲线进行仿真,结果显示光阑小孔越小,获得特征曲线的峰谷值越明显.对不同光阑离透镜焦点的距离值进行Z-扫描闭孔曲线仿真,...     

The Nonlinear Optical Response of Hashin-Shtrikman Geometric Composite Materials

The nonlinear optical response of composite materials consisting of metal grains with insulator shells at finite frequency is investigated. It is found that the surface plasmon peak is stronger and the position of surface plasmon peak is "red-shifted" with the shell being thinner. We also found that the nonlinear optical response is related to the shape of the particles and the dielectric property of the shells.     

非线性光学材料倍频效应测试系统研究

开展了一种红外和可见波段非线性光学性能测试研究。该研究基于二阶非线性光学原理, 结合光电信号探测技术, 提出了一种采用红外OPO激光以及把倍频光及其他光效应产生的光通过谱仪分光并结合CCD阵列探测器加以区分探测的新检测方案。主要解决了测试使用1 064 nm光源时, 材料的倍频信号532 nm被样品吸收后而探测不到倍频信号的缺点, 以及准确测量了倍频信号强度, 排除了其他光学效应产生的噪声干扰。其特点是采用1 064和1 905 nm的双波长激光替代单一波长的激光源, 该方案能适用于可见和红外非线性材料光学性能的测试。研究工作包括测试系统组成, 工作原理和测试方法, 并给出了采用本方法测试KTP, KDP, AGS以及几种新的红外非线性材料的实验结果, 并且发现了几种有前途的非线性光学晶体材料。研究结果表明本方法具有稳定可靠、判别精度高、操作简单等优点, 可以有效地定性或半定量测试材料的可见-红外非线性光学性能, 为研究可见、红外乃至紫外二阶非线性光学材料提供重要的测试手段。     

光学非线性LB膜的时间稳定性与光致漂白效应的关系

用光学二次谐波产生（ＳＨＧ），拉曼散射和紫外－可见吸收光谱等方法研究了偶氮，苯腙及半花菁三种有机染料Ｚ型Ｌａｎｇｍｕｉｒ－Ｂｌｏｄｇｅｔｔ（ＬＢ）多层膜的时间稳定性问题，发现：随着放置时间的推延，其中ＬＢ膜的二次谐波产生信号强度下降，然后逐渐达到稳定；在高压汞灯光照射下，粉末样品中Ｎ＝Ｎ（偶氮），Ｃ＝Ｎ（苯腙），Ｃ＝Ｃ（半花菁）键伸缩振动所对应的拉曼峰强度以及这三类染样在ＬＢ膜样品中对所应的生色团     

氧化铟锡薄膜的二阶非线性光学特性研究

利用二次谐波产生技术研究了氧化铟薄膜的非线性光学特性.氧化甸锡薄膜中多晶晶粒的优先取向,使其产生了非常强的二次谐波信号,并且在一定的薄膜存度以上,随薄膜厚度的增加二次谐波信号显著增强.由于多晶晶粒的优先取向使得薄膜基板平面内存在着非常明显的非线性光学各向异性.     

Dynamic Spin Phenomena in Complex Structures Based on Ferromagnetic Metals and Semiconductors (Scientific Summary)

JETP Letters - A brief review of theoretical and experimental studies of spin phenomena in various hybrid structures based on magnetically ordered metals and semiconductors is presented. In...     

Cascaded Optical Buffer Based on Nonlinear Polarization Rotation in Semiconductor Optical Amplifiers

A cascaded buffer based on nonlinear polarization rotation in semiconductor optical amplifiers is proposed, which is suitable for fast reconfiguration of buffering time at picoseconds. With the proposed buffer, sixty different buffer times are demonstrated at 2.5Gb/s.     

非线性一维光子晶体光开关与光双稳

设计和制备了ZnS/ZnSe叠层共 2 0个周期的非线性一维光子晶体光开关与光双稳器件 理论模拟了波长 5 14 .5nm的氩离子激光 ,在阈值功率密度 1.0× 10 5W/cm2 下 ,完全移出光子禁带 ,实现了光开关 同一器件也可作为光学双稳器件 ,实验测出其阈值功率密度为 1.38× 10 5W/cm2 ,双稳开关时间为 10 0ps 理论与实验结果基本一致     

Dependence of Nonlinear Optical Response of Anatase TiO_2 on Shape and Excitation Intensity

Nonlinear optical(NLO) properties of anatase TiO_2 with nanostructures of nanoparticle(NP), nanowire(NW)and annealed nanowire(NWA) are studied by open-aperture and closed-aperture Z-scan techniques with a femtosecond pulsed laser at wavelengths of 532 nm and 780 nm simultaneously. At 532 nm,when increasing excitation intensity, NLO absorption of TiO_2 NPs transforms from saturable absorption to reverse-saturable absorption.However, NWs and NWAs exhibit the opposite change. At 780 nm,all samples show reverse-saturable absorption, but have different sensitivities to excitation intensity Due to the larger surface-to-volume ratio of NPs and less defects of NWAs by annealing, nonlinear optical absorption coefficients follow the order NPs≥NWs≥NWs.The results also show that these shape and annealing effects are dominant at low excitation intensity but do not exhibit at the high excitation intensity. The NLO refractive index of NPs shows a positive linear relationship with the excitation intensity whereas NW and NWAs exhibit a negative linear relationship.The results could provide some foundational guidance to applications of anatase TiO_2 in optoelectronic devices or other aspects.