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1.
Review on second-harmonic generation of ultrasonic guided waves in solid media (I):Theoretical analyses
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Considering the high sensitivity of the nonlinear ultrasonic measurement technique and great advantages of the guided wave testing method, the use of nonlinear ultrasonic guided waves provides a promising means for evaluating and characterizing the hidden and/or inaccessible damage/degradation in solid media. Increasing attention on the development of the testing method based on nonlinear ultrasonic guided waves is largely attributed to the theoretical advances of nonlinear guided waves propagation in solid media. One of the typical acoustic nonlinear responses is the generation of second harmonics that can be used to effectively evaluate damage/degradation in materials/structures. In this paper, the theoretical progress of second-harmonic generation (SHG) of ultrasonic guided wave propagation in solid media is reviewed. The advances and developments of theoretical investigations on the effect of SHG of ultrasonic guided wave propagation in different structures are addressed. Some obscure understandings and the ideas in dispute are also discussed. 相似文献
2.
We theoretically simulate second-harmonic generation (SHG) in collagen under linearly polarized focused laser beam. With this model, the effects of numerical aperture (NA) and refractive index dispersion on SHG emission have been investigated. Dispersion properties of collagen are significant under incident wavelength in the visible range. Our results show that the efficient SHG is obtained by controlling the NA, and the higher NA is a necessity when the dispersion effect is considered. Our theoretical simulation results provide useful clues for experimental study of microscopic SHG emission in collagen excited by focused beam. 相似文献
3.
L. Marrucci D. Paparo G. Cerrone C. de Lisio E. Santamato S. Solimeno S. Ardizzone P. Quagliotto 《Optics and Lasers in Engineering》2002,37(5)
Optical second-harmonic generation from surfaces has recently proven to be a very effective and versatile probe for surface studies. It allows, among other things, direct probing of molecular adsorption on a solid substrate from a liquid. In this paper we review the most important features of this new technique. We discuss the possibility of applying it to the study of adsorption of ionic surfactants at solid–liquid interfaces, commonly used in a great number of scientific and technological fields including industrial applications. Moreover, we describe the preliminary results of an experiment currently in progress. 相似文献
4.
二维Janus WSSe作为一种新型过渡金属硫族化合物(TMDs)材料由于其独特的面外非对称结构及众多新颖的物理特性,在自旋电子器件中具有巨大的应用潜力.本文基于密度泛函理论的第一性原理平面波赝势方法,通过构建四种掺杂模型W9-xMgxS9Se9(x=0、1、2、3),分别计算了不同浓度Mg掺杂单层WSSe的电子结构和光学性质.结果表明:掺杂使得WSSe由直接带隙半导体变为间接带隙半导体,并且随着掺杂浓度的增加,带隙逐渐减小,费米能级穿过价带,使得掺杂体系变成P型半导体,当x=3时,掺杂体系呈现金属性.此外,掺杂体系的静态介电常数随着掺杂浓度的增加而变大,极化程度显著增强,介电函数虚部和光吸收峰都发生了红移,说明掺杂有利于可见光的吸收.并且,静态折射率随着掺杂浓度的增加而呈现上升趋势,同时消光系数的峰值也与Mg原子的掺杂浓度呈现正相关. 相似文献
5.
Ryusuke Horiuchi Koichi Saiki Koji Adachi Kazuyoku Tei Shigeru Yamaguchi 《Optical Review》2008,15(3):136-139
A high-peak-power and high-repetition-rate fiber laser architecture is successfully demonstrated using a single-stage fiber
amplifier. Nonlinear optical effects in a fiber amplifier degrade the monochromaticity of amplified laser pulses. In general,
it is difficult for a non-monochromatic laser pulse to realize high-order harmonic generation with bulk nonlinear optical
crystals. To overcome this problem, a single-stage amplifier architecture and a gain fiber with a high cladding absorption
coefficient are employed. Furthermore, single-stage amplification enables the use of a multi-longitudinal mode electro-optically
(EO) Q-switched micro seed laser. This architecture can generate a peak power of 100 kW at 50 kHz and an average power of
10 W. A second-harmonic conversion efficiency of 51% is obtained using this architecture and a LiB3O5 (LBO) crystal. 相似文献
6.
On the basis of the vector diffraction theory and Green's function method, this paper investigates the effects of refractive index mismatch on second-harmonic generation (SHG) microscopy. The polarization distribution and SHG intensity are calculated as functions of the sample radius and probe depth. The numerical results show that refractive index mismatch can result in peak intensity degradation, increase secondary lobes and extension of second- harmonic polarization distribution. Because of the attenuation of polarization intensity, the detected SHG intensity significantly decreases with increasing probe depth, which can limit the imaging depth of SHG microscopy inside thick samples. Forward SHG intensity decays slowly than backward SHG, due to the combination of extension second-harmonic polarization distribution and strong dependency of forward SHG on sample radius.[第一段] 相似文献
7.
Xian-Dong Li 《中国物理 B》2022,31(11):110304-110304
The Janus monolayer transition metal dichalcogenides (TMDs) $MXY$ ($M={\rm Mo}$, W, $etc$. and $X, Y={\rm S}$, Se, $etc$.) have been successfully synthesized in recent years. The Rashba spin splitting in these compounds arises due to the breaking of out-of-plane mirror symmetry. Here we study the pairing symmetry of superconducting Janus monolayer TMDs within the weak-coupling framework near critical temperature $T_{\rm c}$, of which the Fermi surface (FS) sheets centered around both $ărGamma$ and $K (K')$ points. We find that the strong Rashba splitting produces two kinds of topological superconducting states which differ from that in its parent compounds. More specifically, at relatively high chemical potentials, we obtain a time-reversal invariant $s + f + p$-wave mixed superconducting state, which is fully gapped and topologically nontrivial, $i.e.$, a $\mathbb{Z}_2$ topological state. On the other hand, a time-reversal symmetry breaking $d + p + f$-wave superconducting state appears at lower chemical potentials. This state possess a large Chern number $|C|=6$ at appropriate pairing strength, demonstrating its nontrivial band topology. Our results suggest the Janus monolayer TMDs to be a promising candidate for the intrinsic helical and chiral topological superconductors. 相似文献
8.
Robert Fischer Solomon M. Saltiel Dragomir N. Neshev Wieslaw Krolikowski Yuri S. Kivshar 《Central European Journal of Physics》2008,6(3):569-574
We investigate the transverse second-harmonic generation in as grown strontium barium niobate (SBN) crystals with a random
structure of anti-parallel ferroelectric domains. We consider both, single and counter-propagating pulse geometries. We investigate
polarization properties of the second harmonic signal and discuss applications of this process for short pulses characterization.
Presented at 9-th International Workshop on Nonlinear Optics Applications, NOA 2007, May 17–20, 2007, Świnoujście, Poland 相似文献
9.
Wen-Jin Yin Xiao-Long Zeng Bo Wen Qing-Xia Ge Ying Xu Gilberto Teobaldi Li-Min Liu 《Frontiers of Physics》2021,16(3):33501
Heterostructure is an effective approach in modulating the physical and chemical behavior of materials. Here, the first-principles calculations were carried out to explore the structural, electronic, and carrier mobility properties of Janus MoSSe/GaN heterostructures. This heterostructure exhibits a superior high carrier mobility of 281.28 cm2·V−1·s−1 for electron carrier and 3951.2 cm2·V−1·s−1 for hole carrier. Particularly, the magnitude of the carrier mobility can be further tuned by Janus structure and stacking modes of the heterostructure. It is revealed that the equivalent mass and elastic moduli strongly affect the carrier mobility of the heterostructure, while the deformation potential contributes to the different carrier mobility for electron and hole of the heterostructure. These results suggest that the Janus MoSSe/GaN heterostructures have many potential applications for the unique carrier mobility. 相似文献
10.
Analytical expressions are obtained for the power of the second harmonic in nonlinear crystals having a regular domain structure
with allowance for thermal blooming for a Gaussian beam of basic radiation in the quasi-stationary plane-wave approximation.
Calculations were carried out in both the approximation of an assigned field of basic radiation and a substantially nonlinear
regime of exhaustion of basic radiation.
Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 67, No. 2, pp,. 257–260, March–April, 2000. 相似文献
11.
Time-domain analysis of second-harmonic generation of primary Lamb wave propagation in an elastic plate
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Within the second-order perturbation approximation,this paper investigates the physical process of generation of the time-domain second harmonic by a primary Lamb wave waveform in an elastic plate.The present work is performed based on the preconditions that the phase velocity matching is satisfied and that the transfer of energy from the primary Lamb wave to the double frequency Lamb wave is not zero.It investigates the influences of the difference between the group velocities of the primary Lamb wave and the double frequency Lamb wave,the propagation distance and the duration of the primary Lamb wave waveform on the envelope shape of the time-domain second harmonic.It finds that the maximum magnitude of the envelope of the second-harmonic waveform can grow within some propagation distance even if the condition of group velocity matching is not satisfied.Our analyses also indicate that the maximum magnitude of the envelope of the second-harmonic waveform is kept constant beyond a specific propagation distance.Furthermore,it concludes that the integration amplitude of the time-domain second-harmonic waveform always grows with propagation distance within the second-order perturbation.The present research yields new physical insight not previously available into the effect of generation of the time-domain second harmonic by propagation of a primary Lamb wave waveform. 相似文献
12.
Nonlinear phase shift and transmission experienced by a beam at the fundamental frequency during electro-optic modulated quasi-phase-matched second-harmonic generation are studied. Numerical results indicate that the nonlinear phase shift of fundamental wave shows a difference of π, while fundamental transmission is controllable only by applying a DC electric field along z-axis. The above effect can be implemented on high-contrast optical switching devices such as Mach-Zehnder push-pull device. The relationships between the characteristic (peak and dip) electric fields and the initial pump intensity are also discussed. 相似文献
13.
Motivated by the synthesis of a Janus monolayer, the new PtSSe transition-metal dichalcogenide (TMD) have attracted remarkable attention due to their characteristic properties. In this work, we calculated the electronic structure, optical properties, and the thermal conductivity of the PtSSe monolayers, and performed a detailed comparison with other TMDs (monolayer PtS2 and PtSe2) using first-principles calculations. The calculated band gaps of the PtS2, PtSSe, and PtSe2 monolayers were 1.76, 1.38, and 1.21?eV, respectively, which are in good agreement with experimental data. At the same time, we observed a larger spin-orbit splitting in the electronic structure of PtSSe monolayers. The optical properties were also calculated and a significant red shift was observed from the PtS2 to PtSSe to PtSe2 monolayers. The lattice thermal conductivity of the PtSSe monolayer at room temperature (36.19?W/mK) is significantly lower than that of the PtS2 monolayer (54.25?W/mK) and higher than that of the PtSe2 monolayer (18.07?W/mK). Our results show that the PtSSe monolayer breaks structural symmetry and has the same ability to reduce the thermal conductivity as MoSSe and ZrSSe monolayers due to the shorter group velocity and the lower converged phonon scattering rate. These results may stimulate further studies on the electronic structure, optical properties, and thermal conductivity of the PtSSe monolayer in both experimental synthesis and theoretical efforts. 相似文献
14.
ABSTRACTWe present the first gauge-origin independent calculations of the circular intensity difference (CID) in electric-field-induced second-harmonic generation (EFISHG), including all contributions up to the electric-quadrupole–magnetic-dipole level. A recursive, open-ended response theory framework in combination with the use of London atomic orbitals allows us to ensure gauge-origin independent results. We apply this approach to study EFISHG-CID in a collection of chiral amino acids. We demonstrate that diffuse polarising basis functions are critical in order to obtain accurate CIDs, and that a basis set of at least aug-cc-pVTZ quality is needed in order to obtain results close to the basis-set limit. The use of London orbitals does not lead to significantly faster basis set convergence, although the improved basis set convergence allows the aug-cc-pVDZ basis set to be used with some confidence for larger molecules. 相似文献
15.
Chenlin Du Bing Teng Zhengping Wang Junhai Liu Xinguang Xu Guibao Xu Kun Fu Jiyang Wang Yaogang Liu Zongshu Shao 《Optics & Laser Technology》2002,34(4)
We have investigated the acousto-optically Q-switched intracavity second-harmonic generation of 1.06 μm in a 1.9-mm-long BiB3O6 crystal, cut for type-I phase-matching direction of (θ,)=(168.9°,90°), performed in a diode-end-pumped Nd:YVO4 laser. When the incident pump power was 4.3 W at 30 kHz of pulse repetition frequency, a maximum average green output power of 480 mW, the shortest pulse with FWHM width of 72 ns, the highest single pulse energy of 16 μJ and the maximum peak power of 222 W were obtained, giving the corresponding optical conversion efficiency of 11.2%. The effect of varying temperature in BIBO crystal on the average green output power was also investigated. 相似文献
16.
Hideki Nakayama Okihiro Sugihara Hisashi Fujimura Ryoka Matsushima Naomichi Okamoto 《Optical Review》1995,2(4):236-238
Sol-gel processed poled silica films doped with novel nonlinear organic materials, thiazole azo dye (TA), are prepared in high concentration. Resonance enhanced second-order nonlinear optical coefficient of d33 = 154 pm/V is obtained from TA doped silica film (40 wt%) for the fundamental wavelength of 1064 nm. The value d33 is unvaried for at least 100 h under a high temperature condition (100°C) without any relaxation. Wavelength dependent second-order nonlinearity is also measured. 相似文献
17.
本文从经典电磁理论出发,分析了有机环形光纤中二次谐波产生(SHG)的转换效率,着重讨论利用环形光纤中模式的色散特性实现相位匹配等问题。报道了采用LB膜方法,制成半花菁环形光纤,由高灵敏度光检测计测出在强泵光(1.06μm,YAG激光)作用下该光纤中的二次谐波产生的实验结果。 相似文献
18.
P. Fischer 《Molecular physics》2013,111(14):1857-1868
Coherent second-order nonlinear optical processes are symmetry forbidden in centrosymmetric environments in the electric-dipole approximation. In liquids that contain chiral molecules, however, and which therefore lack mirror image symmetry, coherent sum-frequency generation is possible, whereas second-harmonic generation remains forbidden. Here we apply the theory of molecular quantum electrodynamics to the calculation of the matrix element, transition rate, and integrated signal intensity for sum-frequency and second-harmonic generation taking place in a chiral liquid in the presence and absence of a static electric field, to examine which coherent and incoherent processes exist in the electric-dipole approximation in liquids. Third- and fourth-order time-dependent perturbation theory is employed in combination with single-sided Feynman diagrams to evaluate two contributions arising from static field-free and field-induced processes. It is found that, in addition to the coherent term, an incoherent process exists for sum-frequency generation in liquids. Surprisingly, in the case of dc-field-induced second-harmonic generation, the incoherent contribution is found to always vanish for isotropic chiral liquids even though hyper-Rayleigh second-harmonic generation and electric-field-induced second-harmonic generation are both independently symmetry allowed in any liquid. 相似文献
19.
Characterization of inner layer thickness change of a composite circular tube using nonlinear circumferential guided wave:A feasibility study
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Ming-Liang Li 《中国物理 B》2021,30(8):84301-084301
The feasibility of using the nonlinear effect of primary circumferential guided wave (CGW) propagation for characterizing the change of inner layer thickness of a composite circular tube (CCT) has been investigated. An appropriate mode pair of the fundamental and double-frequency CGWs (DFCGWs) has been selected to enable the second harmonics of primary wave mode in the given CCT to accumulate along the circumferential direction. When changes in the inner layer thickness (described as the equivalent inner layer thickness) take place, the corresponding nonlinear CGW measurements are conducted. It is found that there is a direct correlation between change of equivalent inner layer thickness of the CCT and the relative acoustic nonlinearity parameter (Δβ) measured with CGWs propagating through one full circumference, and that the effect of second-harmonic generation (SHG) is very sensitive to change in the inner layer thickness. The experimental result obtained demonstrates the feasibility for quantitatively assessing the change of equivalent inner layer thickness in CCTs using the effect of SHG by primary CGW propagation. 相似文献
20.
F. R. Aussenegg A. Leitner H. Gold 《Applied Physics A: Materials Science & Processing》1995,60(2):97-101
In metal-island films consisting of nanometer particles on a transparent substrate irradiated light fields can be locally enhanced by electron-plasma resonances. Therefore, nonlinear optical processes should be enhanced dramatically. However, second-order nonlinear processes as second-harmonic generation occuring in the surface are strongly reduced by the centrosymmetric shape of the metal particles. It is found that this surface-specific contribution to second-harmonic generation is less enhanced, as is expected from the field enhancement. The bulk contribution, at smooth metal surfaces known to be much weaker than the contribution from the real surface, is strongly enhanced by the plasma resonances without symmetry restrictions and becomes comparably important.Paper presented at the 129th WE-Heraeus-Seminar on Surface Studies by Nonlinear Laser Spectroscopies, Kassel, Germany, May 30 to June 1, 1994. 相似文献