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Enhancement of Sensitivity by Initial phase matching in SU(1,1) Interferometers

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Communications in Theoretical Physics 2019年第1期71卷 37-42页

作者：肖骁梁宏宾李国龙王晓光 Zhejiang Institute of Modern Physics Department of Physics Zhejiang University

We derive a general phase-matching condition(PMC) for enhancement of sensitivity in SU(1,1) interferometers. Under this condition, the quantum Fisher information(QFI) of two-mode SU(1,1) interferometry becomes maximal with respect to the relative phase of two modes, for the case of an arbitrary state in one input port and an even(odd) state in the other port, and the phase sensitivity is enhanced. We also find that optimal parameters can let the QFI in some areas achieve the Heisenberg limit for both pure and mixed initial states. As examples, we consider several input states: coherent and even coherent states, squeezed vacuum and even coherent states, squeezed thermal and even coherent states. Furthermore, in the realistic scenario of the photon loss channel, we investigate the effect of photon losses on QFI with numerical studies. We find the PMC remains unchanged and is not affected by the transmission coefficients for the above input states. Our results suggest that the PMC can exist in various kinds of interferometers and the phase-matching is robust to even strong photon losses.

关键词： quantum Fisher information SU(1,1) parameter estimation phase-matching condition

phase-matching and Parametric Conversion for the Mid-Infrared in As<sub>2</sub>S<sub>3</sub>Waveguides

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Optics and Photonics Journal 2012年第4期2卷 260-264页

作者： Qi Chen Xin Wang Christi Madsen Department of Electrical & Computer Engineering Texas A&M University College Station Texas USA

We illustrate two As2S3 waveguide designs for four-wave mixing, which can generate 3.03 μm mid-infrared light from a 1.55 μm near-infrared signal source and a 2.05 μm pump source. Through simulations, we verify that four-wave mixing phase-matching efficiencies up to 100% can be achieved using dispersion engineering to maintain the dispersion at 2.05 μm near to zero. The best conversion efficiency is –10 dB. When the waveguide length is 1 cm, the parametric conversion bandwidth is 1525 nm. We also evaluated the shift of 100% phase-matching efficiency wavelengths based upon fabrication tolerances.

关键词： As2S3 Mid-Infrared phase-matching Four-Wave Mixing

Evaluating refractive index and birefringence of nonlinear optical crystals:Classical methods and new developments

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Chinese Journal of Structural Chemistry 2023年第1期42卷 46-63页

作者： Qi Shi Lingyun Dong Ying Wang College of Chemistry and Materials Science Hebei UniversityBaoding071002China College of Biochemistry and Environmental Engineering Baoding UniversityBaoding071002China

Nonlinear optical(NLO)materials play an increasingly important role in laser technology.Birefringence is one of the most important parameters for NLO materials to realize angle phase-matching conditions.In comparison with other desirable optical properties,the availability of birefringence and refractive index dispersion is especially problematic owing to the strict requirements for single crystals.In this review,we described how to obtain the refractive index and birefringence of NLO materials from crystals sub-millimeters to centimeters in size.Espe-cially,recently developed methods including the minimum deflection angle method,auto-collimation method,prism coupling method,oil immersion technique,interference color method,and theoretical calculation(DFT)for rapid assessment of birefringence are summarized,the contents of which are mainly focused on the principles and typical applications,together with the advantages and drawbacks.In addition,representative examples of bire-fringent measurements were presented.The purpose of this work is to provide a useful perspective on the characterization of birefringence for NLO materials.It is hoped that this review can give a clear description of the birefringence measurements and accelerate the discovery of new NLO crystals.

关键词： Nonlinear optical crystals Refractive index Birefringence DFT calculation phase-matching

Tailoring OAM spectrum of high-order harmonic generation driven by two mixed Laguerre–Gaussian beams with nonzero radial nodes

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Chinese Physics B 2023年第12期32卷 80-89页

作者：汪倍羽韩嘉鑫金成 Institute for Advanced Materials and Guangdong Provincial Key Laboratory of Quantum Engineering and Quantum Materials South China Academy of Advanced OptoelectronicsSouth China Normal UniversityGuangzhou 510006China Laboratory of Solid State Microstructures and Innovation Center of Advanced Microstructures Nanjing UniversityNanjing 210093China

The extreme ultraviolet(XUV)light beam carrying orbital angular momentum(OAM)can be produced via high-order harmonic generation(HHG)due to the interaction of an intense vortex infrared laser and a gas medium.Here we show that the OAM spectrum of vortex HHG can be readily tailored by varying the radial node(from 0 to 2)in the driving laser consisting of two mixed Laguerre-Gaussian(LG)beams.We find that due to the change in spatial profile of HHG,the distribution range of the OAM spectrum can be broadened and its shape can be modified by increasing the radial node.We also show that the OAM mode range becomes much wider and its distribution shape becomes more symmetric when the harmonic order is increased from the plateau to the cutoff when the driving laser has the nonzero radial nodes.Through the map of coherence length and the evolution of harmonic field in the medium,we reveal that the favorable off-axis phase-matching conditions are greatly modified due to the change of intensity and phase distributions of driving laser with the radial node.We anticipate this work to stimulate some interests in generating the XUV vortex beam with tunable OAM spectrum through the gaseous HHG process achieved by manipulating the mode properties of the driving laser beam.

关键词： orbital angular momentum(OAM)spectrum high-order harmonic generation Laguerre–Gaussian beam radial nodes phase-matching

Atomically phase-matched second-harmonic generation in a 2D crystal

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Light(Science & Applications) 2016年第1期5卷 542-547页

作者： Mervin Zhao Ziliang Ye Ryuji Suzuki Yu Ye Hanyu Zhu Jun Xiao Yuan Wang Yoshihiro Iwasa Xiang Zhang Department of Mechanical Engineering NSF Nanoscale Science and Engineering CenterUniversity of CaliforniaBerkeleyCA 94720USA Materials Sciences Division Lawrence Berkeley National LaboratoryBerkeleyCA 94720USA Quantum-phase Electronics Center(QPEC)and Department of Applied Physics The University of TokyoTokyo 113-8656Japan RIKEN Center for Emergent Matter Science(CEMS) Wako 351-0198Japan Department of Physics King Abdulaziz UniversityJeddah 21589Saudi Arabia

Second-harmonic generation(SHG)has found extensive applications from hand-held laser pointers to spectroscopic and microscopic techniques.Recently,some cleavable van der Waals(vdW)crystals have shown SHG arising from a single atomic layer,where the SH light elucidated important information such as the grain boundaries and electronic structure in these ultra-thin materials.However,despite the inversion asymmetry of the single layer,the typical crystal stacking restores inversion symmetry for even numbers of layers leading to an oscillatory SH response,drastically reducing the applicability of vdW crystals such as molybdenum disulfide(MoS_(2)).Here,we probe the SHG generated from the noncentrosymmetric 3R crystal phase of MoS_(2).We experimentally observed quadratic dependence of second-harmonic intensity on layer number as a result of atomically phase-matched nonlinear dipoles in layers of the 3R crystal that constructively interfere.By studying the layer evolution of the A and B excitonic transitions in 3R-MoS_(2) using SHG spectroscopy,we also found distinct electronic structure differences arising from the crystal structure and the dramatic effect of symmetry and layer stacking on the nonlinear properties of these atomic crystals.The constructive nature of the SHG in this 2D crystal provides a platform to reliably develop atomically flat and controllably thin nonlinear media.

关键词： atomically thin phase-matching second-harmonic generation 3R-MoS_(2)

Intersubband absorption with difference-frequency generation in GaAs asymmetric quantum wells

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Chinese Physics B 2012年第8期21卷 252-257页

作者：曹小龙李忠洋姚建铨王与烨朱能念钟凯徐德刚 College of Precision Instrument and Opto-electronics Engineering Institute of Laser and Opto-electronicsTianjin University Key Laboratory of Opto-electronics Information Technology(Tianjin University) Ministry of Education Institute of Electric Power North China University of Water Resources and Electric Power

An asymmetric quantum well （AQW） is designed to emit terahertz （THz） waves by using difference frequency generation （DFG） with the structure of GaAs/Al0.2Ga0.8As/Al0.5Ga0.sAs. The characteristics of absorption coefficients are analysed under the parabolic and non-parabolic energy-band conditions in detail. We find that the absorption coefficients vary with the two pump optical intensities, and they reach the maxima when the pump wavelengths are given as λp1 = 9.70 μm and λp2 = 10.64 μm, respectively. Compared with non-parabolic conditions, the total absorption coefficient under parabolic conditions shows a blue shift, which is due to the increase in the energy difference between the ground and excited states. By adjusting the two pump optical intensities, the wave vector phase-matching condition inside the AQW is satisfied.

关键词： asymmetric quantum wells absorption coefficient THz-wave phase-matching

Polarisation-sensitive four-wave mixing and soliton self-frequency shift effect in the highly birefringent photonic crystal fibre

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Chinese Physics B 2010年第7期19卷 344-349页

作者：苑金辉桑新柱余重秀忻向军李曙光周桂耀侯蓝田 Key Laboratory of Information Photonics and Optical Communications Ministry of EducationInstitute of Optical Communication and OptoelectronicsBeijing University of Posts and Telecommunications Institute of Infrared Optical Fibers and Sensors College of Information Science and EngineeringYanshan University

By adjusting the polarisation state of the pump at 805 nm parallel to slow （x） and fast （y） axes of the highly birefringent photonic crystal fibre with zero dispersion wavelengths 790 nm and 750 nm, this paper demonstrates the efficient polarisation-sensitive four wave mixing involved in pump, anti-Stokes and Stokes signals and soliton self- frequency shift effects induced by the phase-matching between red-shifted solitons and blue-shifted dispersive waves. If the reduction of coupling efficiency to the circular pump laser mode or other circular fibres due to asymmetry of the core is neglected, more than 98% of the total input power is kept in a single linear polarisation. Controlled dispersion characteristic of the doublet of fundamental guided-modes results in achieving light field strongly confined in principal axes of photonic crystal fibre, and enhancing the corresponding nonlinear-optical process through the remarkable nonlinear birefringence.

关键词： highly birefringent photonic crystal fibre four wave mixing soliton self-frequency shift phase-matching

Coherent X-ray mirage: discovery and possible applications

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High Power Laser Science and Engineering 2014年第2期2卷 1-6页

作者： Tatiana Pikuz Anatoly Faenov Sergey Magnitskiy Nikolay Nagorskiy Momoko Tanaka Masahiko Ishino Masaharu Nishikino Yuji Fukuda Masaki Kando Yoshiaki Kato Tetsuya Kawachi Quantum Beam Science Directorate Japan Atomic Energy Agency Kizugawa Kyoto 619-0215 Japan Joint Institute for High Temperatures Russian Academy of Sciences Moscow 125412 Russia Institute for Academic Initiatives Osaka University International Laser Center of M.V. Lomonosov Moscow State University The Graduate School for the Creation of New Photonics Industries Hamamatsu Shizuoka 431-1202 Japan

In the far field of the intensity distribution of the beam delivered by a two-stage transient–collisional excitation X-ray laser(XRL), a non-expected interference pattern that is stable from shot to shot has been discovered. It is demonstrated that the interference is caused by the emergence of an imaginary source in the amplifying plasma, which is phase matched to the radiation of the generator. The observed phenomenon is called an X-ray coherent mirage. To explain the obtained results, a new theoretical approach is developed. The basic essential conditions for formation of the X-ray mirage are formulated, and possible applications are discussed. This paper details the experiments, including the formulation of the necessary and sufficient conditions for formation of the X-ray mirage, and possible applications are discussed.

关键词： coherent seeded beams mirage phase-matching X-ray lasers X-ray plasma optics

深紫外氟化硼酸盐双折射率和折射率色散的性能增益研究

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Science China Materials 2020年第8期63卷 1480-1488页

作者：杨志华阿布都卡地·吐地雷兵华潘世烈 CAS Key Laboratory of Functional Materials and Devices for Special Environments Xinjiang Technical Institute of Physics&ChemistryCASXinjiang Key Laboratory of Electronic Information Materials and DevicesUrumqi 830011China Center of Materials Science and Optoelectronics Engineering University of Chinese Academy of SciencesBeijing 100049China

作为紫外/深紫外非线性光学材料的潜在体系,氟化硼酸盐已引起了该领域的广泛关注.鉴于该类体系中双折射和折射率色散的影响因素尚未明确,我们设计了可能的氟化硼酸盐基团,分析了光学各向异性以探索其对双折射率的影响.通过响应电荷分布... 详细信息

作为紫外/深紫外非线性光学材料的潜在体系,氟化硼酸盐已引起了该领域的广泛关注.鉴于该类体系中双折射和折射率色散的影响因素尚未明确,我们设计了可能的氟化硼酸盐基团,分析了光学各向异性以探索其对双折射率的影响.通过响应电荷分布各向异性近似,我们进一步证明和筛选了有利于双折射率的微观基团,并系统地探讨了可有效调节双折射率的功能模块.基于发展的折射率色散分析方法,我们发现氟化硼酸盐基团的引入有利于降低该类体系在深紫外区的折射率色散,从而获得较短的相位匹配波长.该研究为功能驱动的材料设计提供了一条途径.

关键词： nonlinear optical crystal deep-ultraviolet borate birefringence phase-matching