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1.
Huang Ji-ping 《Frontiers of Physics in China》2007,2(1):17-30
We review the recent theoretical investigation on enhanced second-harmonic generation (SHG) in soft nonlinear optical materials
based on ferrofluids, graded metallic films, and graded metal-dielectric films of anisotropic particles. The SHG of soft ferrofluid-based
nonlinear optical materials possess magnetic-field controllabilities, i.e., magnetic-field-controllable anisotropy, red-shift
and enhancement, which are caused to appear by the shift of a resonant plasmon frequency due to the formation of the chains
of the coated nanoparticles. Both graded metallic films and graded metal-dielectric films of anisotropic particles can serve
as a novel optical material for producing a broad structure in both the linear and SHG response and an enhancement in the
SHG signal, due to the local field effects.
相似文献
2.
Aktsipetrov OA Misuryaev TV Murzina TV Blinov LM Fridkin VM Palto SP 《Optics letters》2000,25(6):411-413
Optical second-harmonic generation (SHG) is used as a noninvasive probe of two-dimensional (2D) ferroelectricity in Langmuir-Blodgett (LB) films of the copolymer vinylidene fluoride with trifluoroethylene. The surface 2D ferroelectric-paraelectric phase transition in the topmost layer of the LB films and a thickness-independent (almost 2D) transition in the bulk of these films are observed in temperature studies of SHG. 相似文献
3.
We review recent theoretical progress in understanding physical processes of composite effects on enhanced third-order nonlinear optical responses of various kinds of the recently-proposed nonlinear optical materials, namely, colloidal nanocrystals with inhomogeneous metallodielectric particles or a graded-index host, metallic films with inhomogeneous microstructures adjusted by ion doping or temperature gradient, composites with compositional gradation or graded particles, and magneto-controlled ferrofluid-based nonlinear optical materials. 相似文献
4.
5.
I.A. KolmychekT.V. Murzina 《Journal of magnetism and magnetic materials》2011,323(23):2973-2976
Magnetization-induced effects in the symmetry properties of optical second harmonic generation (SHG) are studied in thin cobalt films. We demonstrate that the application of an external magnetic field leads to the appearance of a strong SHG azimuthal anisotropy from the isotropic Au/Co structure. Symmetry analysis of the SHG dependencies, supported by the SHG interferometry measurements, indicates that the effective magnetic and crystallographic second-order susceptibilities are both of the same order of magnitude. 相似文献
6.
W. Cheikh-Rouhou L.C. Sampaio B. Bartenlian P. Beauvillain A. Brun J. Ferré P. Georges J.-P. Jamet V. Mathet A. Stupakewicz 《Applied physics. B, Lasers and optics》2002,74(7-8):665-670
The optical and magneto-optical second harmonic reflectivity response of Au/Co/Au/Cu multilayers grown on vicinal Si (111)
substrates has been studied. These azimuthal optical non-linear experiments check the uniaxial character of the crystallinity
of the Au buffer layer and the magnetic behavior of the ultrathin Co films in the metallic multilayer. They clearly show the
strong dependence of the growth parameters and the misorientation of the vicinal surface on the SHG reflectivity signals.
This uniaxial behavior is also correlated to linear MOKE experiments on the magnetic anisotropy with an easy magnetization
axis parallel to the step edges.
Received: 16 October 2001 / Published online: 29 May 2002 相似文献
7.
Dielectric chiral metasurfaces can generate harmonic waves with high efficiency and strong circular dichroism (CD), when they are supported by metallic substrates. Numerical results show that the second-harmonic generation (SHG) efficiency of about 10−3% for a peak pump intensity of about 5 GW cm−2 can be achieved in the blue-UV, and the SHG CD reaches up to about 1.8, from a metasurface of Z-shaped lithium niobate nanoantenna array supported by gold substrate. Highly efficient and strong circular dichroic nonlinear responses are attributed to the plasmon-assisted local field enhancement in the dielectric chiral nanoantennae adjacent to the metallic substrate. 相似文献
8.
利用1.064μm基频超短脉冲激光,使用光学二次谐波方法研究了超高真空中蒸镀在多晶银表面上的C60薄膜紫外光照射下的光聚合现象,发现聚合以后的C60二阶非线性响应增强,同时观察到光聚合的饱和效应,C60光聚合二阶非线性的提高可以用电四极了磁偶极子对二次谐波贡献的增强来解释。 相似文献
9.
利用非线性传递矩阵方法研究了Voigt位型下电介质/反铁磁/电介质 结构二次谐波生成的非倒易性. 研究发现外加静磁场反向和电介质层排序翻转均对二次谐波输出产生影响, 出现了二次谐波生成的非倒易性. 二次谐波生成非倒易性频率区域在反铁磁共振区, 此区间正处于THz频段. 随着入射角度的增加, 非倒易性的效果越来越明显. 研究二次谐波生成的非倒易性, 可为反铁磁器件的设计加工提供理论支持. 相似文献
10.
11.
K. Pedersen T.B. Kristensen T.G. Pedersen P. Morgen Z. Li S.V. Hoffmann 《Applied physics. B, Lasers and optics》2002,74(7-8):677-682
Thin noble metal films (Ag, Au and Cu) on Si (111) have been investigated by optical second-harmonic generation (SHG) in combination
with synchrotron radiation photoemission spectroscopy. The valence band spectra of Ag films show a quantization of the sp-band
in the 4-eV energy range from the Fermi level down to the onset of the d-bands. For Cu and Au the corresponding energy range
is much narrower and quantization effects are less visible. Quantization effects in SHG are observed as oscillations in the
signal as a function of film thickness. The oscillations are strongest for Ag and less pronounced for Cu, in agreement with
valence band photoemission spectra. In the case of Au, a reacted layer floating on top of the Au film masks the observation
of quantum well levels by photoemission. However, SHG shows a well-developed quantization of levels in the Au film below the
reacted layer. For Ag films, the relation between film thickness and photon energy of the SHG resonances indicates different
types of resonances, some of which involve both quantum well and substrate states.
Received: 16 October 2001 / Revised version: 14 March 2002 / Published online: 29 May 2002 相似文献
12.
We study the enhancement of the second-harmonic generation (SHG) coefficient in a random composite consisting of ellipsoidal particles with a core–shell structure in a linear dielectric host. The material making up the ellipsoidal core is assumed to be dielectric, but with a nonlinear susceptibility for SHG. The coating material is assumed to be metallic with a linear susceptibility. The effective SHG coefficient is derived and its expression is related to various local field factors. The numerical calculations of the effective SHG response per unit volume of nonlinear material can be greatly enhanced at certain frequencies. For coated ellipsoidal particles, the core–shell structure and the particle shape allow for tuning of the resonance through the choice of material parameters and/or the ratio of the core to shell volume fraction and the depolarization factor of the particles. 相似文献
13.
以1.06μm激光为基频光,测量了金、铜、铂、银膜的反射二次谐波随基频光偏振角的变化,在b=-1的条件下拟合求得了这几种样品面谐波电流的唯象参数“a”值。 相似文献
14.
The observation of optical second harmonic generation (SHG) from wetspun films of Na-DNA is reported. The SHG signal is stronger at a relative humidity of 92% (corresponding to the B conformation of Na-DNA) than at low humidity of -33% (corresponding to a disordered conformation of Na-DNA). The strength of the SHG signal is also dependent on the orientation of the incident laser beam polarization with respect to the DNA helical axes. 相似文献
15.
Nonlinear optical and electrostatic force microscopy for ferroelectric polarization imaging 总被引:1,自引:0,他引:1
E.D. Mishina N.E. Sherstyuk K.A. Vorotilov A.S. Sigov R. Barberi M.P. Moret F. Manders M.P. De Santo P.K. Larsen T. Rasing 《Applied physics. B, Lasers and optics》2002,74(7-8):783-788
Second-harmonic generation (SHG)-based nonlinear optical microscopy is used for spatially resolved imaging of the polarization
switching in lead zirconium titanate ferroelectric thin films. The local SHG hysteresis loops reveal a strong dependence on
film composition and structure. The SHG microscopy results are in good agreement with the efficiency of electrostatic force
microscopy writing and allow us to predict the microscopic dielectric memory efficiency, both in contact and contact-less
ways.
Received: 15 January 2001 / Revised version: 27 March 2002 / Published online: 6 June 2002 相似文献
16.
The second harmonic generation (SHG) of light diffusely scattered by cold-deposited silver films is negligible with respect to the specular intensities. Therefore, a cold-deposited silver film is well approximated by a homogeneous effective medium. The intensities of SHG at 1.06 μm and the optical absorption at 0.53 μm depend on both the square of the internal effective field at 0.53 μm and a change in the same way when annealing the film. This can be understood by the assumption that SHG is also mainly following the electric field within the metal phase and surface contributions to SHG interfere destructively. This is corroborated by the observation that the SHG intensity does not show the ‘chemical first layer effects’ seen by surface-enhanced Raman scattering (SERS). 相似文献
17.
18.
Second-harmonic generation (SHG) results for Ni and Co films on Cu (001) have been reinvestigated regarding the depth sensitivity
of this technique for thin films. We find that tangential components of the nonlinear susceptibility are much more sensitive
to real film properties than normal components, which are confined to surfaces and interfaces. In consequence, for SHG experiments
on ultra-thin metal films, polarization combinations should be favored that possess only tangential susceptibility components,
even though the yield is weaker. Additional phase measurements are necessary to obtain full information about the film.
Received: 20 January 2002 / Published online: 6 June 2002 相似文献
19.
采用紫外可见吸收和二次谐波产生技术研究了“推-拉”型偶氮苯分子Langmuir-Blodgett(LB)膜的光谱和二阶非线性光学特性.4-硝基-4′-氨基偶氮苯(NAA)分子能制成很好的LB多层膜,在稀溶液中以单体的反式异构体形式存在,在膜中主要以J-聚集体的形式存在,LB膜的紫外可见吸收谱的吸收峰较之溶液的发生了52 nm的红移.NAALB膜的二阶非线性极化率χ(2)为19.59×10-8 esu,一阶超极化率β值较大,约为1.974×10-29 esu.其光学二阶非线性起源于电偶极子机制. 相似文献
20.
氰基团修饰的苯腙类有机分子掺杂极化聚合膜光学非线性的研究 总被引:2,自引:2,他引:0
采用实时测量光学二次谐波产生(SHG)和吸收光谱的方法对苯腙类有机分子NDA及一种新合成的经氰基团修饰的有机分子CNDA掺杂PMMA极化聚合膜的非线性光学性质进行了研究。实验中发现两种掺杂极化聚合膜的最佳电晕极化温度均低于它们的玻转温度,CNDA/PM-MA极化掺杂聚合膜的χ(2)较NDA/PMMA极化聚合膜的大。结合极化前和极化后吸收峰强度的变化,得到CNDA分子的非线性极化率β约为146×10-30esu。在撤离极化场后,CNDA/PMMA的二次谐波强度的弛豫也比NDA/PMMA的慢 相似文献