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nonlinear optics with structured light

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Opto-Electronic Advances 2022年第6期5卷 1-19页

作者： Wagner Tavares Buono Andrew Forbes School of Physics University of the WitwatersrandPrivate Bag 3Johannesburg 2050South Africa.

The interest in tailoring light in all its degrees of freedom is steadily gaining traction,driven by the tremendous developments in the toolkit for the creation,control and detection of what is now called structured light.Because the complexity of these optical fields is generally understood in terms of interference,the tools have historically been linear optical elements that create the desired superpositions.For this reason,despite the long and impressive history of nonlinear optics,only recently has the spatial structure of light in nonlinear processes come to the fore.In this review we provide a concise theoretical framework for understanding nonlinear optics in the context of structured light,offering an overview and perspective on the progress made,and the challenges that remain.

关键词： wave mixing parametric conversion high harmonic generation structured light photonic crystals holography nonlinear optics second harmonic generation metasurfaces

Theoretical Studies on the Electronic Structure of Nano-graphenes for Applications in nonlinear optics

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Chemical Research in Chinese Universities 2022年第2期38卷 579-587页

作者： CHEN Kaichun ZHENG Xuelian YANG Cuicui TIAN Wei Quan LI Weiqi YANG Ling Chongqing Key Laboratory of Theoretical and Computational Chemistry College of Chemistry and Chemical EngineeringChongqing UniversityHuxi CampusChongqing 401331P.R.China School of Physics Harbin Institute of TechnologyHarbin 150001P.R.China Collaborative Innovation Center of Extreme optics Shanxi UniversityTaiyuan 030006P.R.China MIIT Key Laboratory of Critical Materials Technology for New Energy Conversion and Storage Institute of Theoretical and Simulational ChemistrySchool of Chemistry and Chemical EngineeringHarbin Institute of TechnologyHarbin 150001P.R.China

In this work,azulene is introduced into nano-graphene with coronene center to enhance the second-order nonlinear optical(NLO)properties.The sum-over-states(SOS)model based calculations demonstrate that dipolar contributions are larger than octupolar contributions to the static first hyperpolarizability(〈β0〉)in most nano-graphenes except those with high symmetry(e.g.,a C2v nano-graphene has octupolar contributionsΦJ=3 up to 59.0%of the〈β0〉).Nano-graphenes containing two parallel orientating azulenes(i.e.,Out-P and Out-Ps)have large dipole moments,while their ground state is triplet.Introducing B/N/BN atoms into the positions with a high spin density transfers the ground state of Out-P and Out-Ps to closed-shell singlet,and the Out-Ps-2N has a large〈β0〉of 1621.67×10−30 esu.Further addition of an electron donor(NH2)at the pentagon end enhances the〈β0〉to 1906.22×10−30 esu.The two-dimensional second-order NLO spectra predicted by using the SOS model find strong sum frequency generations and difference frequency generations,especially in the near-infrared and visible regions.The strategies to stabilize the electronic structure and improve the NLO properties of azulene-defect carbon nanomaterials are proposed,and those strategies to engineer nano-graphenes to be semiconducting while maintaining theπ-framework are exten-dable to other similar systems.

关键词： nonlinear optics Azulene-defect nano-graphene Two-dimensional second-order nonlinear optical spectrum Sum frequency generation Difference frequency generation

nonlinear optics in all-dielectric nanoantennas and metasurfaces:a review

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Advanced Photonics 2019年第2期1卷 20-33页

作者： Basudeb Sain Cedrik Meier Thomas Zentgraf University of Paderborn Department of PhysicsPaderbornGermany

Free from phase-matching constraints,plasmonic metasurfaces have contributed significantly to the control of optical nonlinearity and enhancement of nonlinear generation efficiency by engineering subwavelength meta-atoms.However,high dissipative losses and inevitable thermal heating limit their applicability in nonlinear nanophotonics.All-dielectric metasurfaces,supporting both electric and magnetic Mie-type resonances in their nanostructures,have appeared as a promising alternative to nonlinear plasmonics.High-index dielectric nanostructures,allowing additional magnetic resonances,can induce magnetic nonlinear effects,which,along with electric nonlinearities,increase the nonlinear conversion efficiency.In addition,low dissipative losses and high damage thresholds provide an extra degree of freedom for operating at high pump intensities,resulting in a considerable enhancement of the nonlinear processes.We discuss the current state of the art in the intensely developing area of all-dielectric nonlinear nanostructures and metasurfaces,including the role of Mie modes,Fano resonances,and anapole moments for harmonic generation,wave mixing,and ultrafast optical switching.Furthermore,we review the recent progress in the nonlinear phase and wavefront control using all-dielectric metasurfaces.We discuss techniques to realize alldielectric metasurfaces for multifunctional applications and generation of second-order nonlinear processes from complementary metal–oxide–semiconductor-compatible materials.

关键词： nonlinear optics dielectric metasurfaces Mie modes Fano resonances anapole modes harmonic generation

nonlinear optics of two-dimensional transition metal dichalcogenides

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InfoMat 2019年第3期1卷 317-337页

作者： Xinglin Wen Zibo Gong Dehui Li School of Optical and Electronic Information Huazhong University of Science and TechnologyWuhanChina Wuhan National Laboratory for Optoelectronics Huazhong University of Science and TechnologyWuhanChina

nonlinear optics(NLO)of transition metal dichalcogenides(TMDs)is promising for the on-chip photonic and optoelectronic applications.In this review,we will survey the current progress of NLO in TMDs.First,we will brief the basic theory of the NLO in TMDs.Second,several important nonlinear processes in TMDs such as harmonic generation,four-wave mixing,saturable absorption,and two-photon absorption will be presented and their potential applications are also discussed.Third,the main strategies to tune,modulate,and enhance the NLO in TMDs are reviewed,including the excitonic effect,symmetry modulation,optical cavity enhancement,valley selection,edge state,and material phase.Finally,we give an outlook regarding some important issues and directions of NLO in TMDs.

关键词： NLO modulation and enhancement nonlinear devices nonlinear optics transition metal dichalcogenides

Programming nonlinear propagation for efficient optical learning machines

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Advanced Photonics 2024年第1期6卷 73-83页

作者： Ilker Oguz Jih-Liang Hsieh Niyazi Ulas Dinc Ugur Tegin Mustafa Yildirim Carlo Gigli Christophe Moser Demetri Psaltis École Polytechnique Fédérale de Lausanne Institute of Electrical and Micro EngineeringEcublensSwitzerland Koc University Department of Electrical and Electronics EngineeringIstanbulTurkey

The ever-increasing demand for training and inferring with larger machine-learning models requires more efficient hardware solutions due to limitations such as power dissipation and scalability.optics is a promising contender for providing lower power computation,since light propagation through a nonabsorbing medium is a lossless operation.However,to carry out useful and efficient computations with light,generating and controlling nonlinearity optically is a necessity that is still elusive.Multimode fibers(MMFs)have been shown that they can provide nonlinear effects with microwatts of average power while maintaining parallelism and low loss.We propose an optical neural network architecture that performs nonlinear optical computation by controlling the propagation of ultrashort pulses in MMF by wavefront shaping.With a surrogate model,optimal sets of parameters are found to program this optical computer for different tasks with minimal utilization of an electronic computer.We show a remarkable decrease of 97%in the number of model parameters,which leads to an overall 99%digital operation reduction compared to an equivalently performing digital neural network.We further demonstrate that a fully optical implementation can also be performed with competitive accuracies.

关键词： neural networks nonlinear optics fiber optics surrogate optimization neuromorphic computing wavefront shaping

Ultrabroadband second-harmonic generation via spatiotemporal-coupled phase matching

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Chinese optics Letters 2024年第1期22卷 105-112页

作者：陶昱东朱文涛章艳芳马金贵王静袁鹏张浩朱鹤元钱列加 Key Laboratory for Laser Plasma Shanghai Jiao Tong UniversityShanghai 200240China Key Laboratory of Micro and Nano Photonic Structures Fudan UniversityShanghai 200433China Tsung-Dao Lee Institute Shanghai Jiao Tong UniversityShanghai 200240China

We propose a spatially chirped quasi-phase-matching(QPM)scheme that enables ultrabroadband second-harmonic-generation(SHG)by using a fan-out QPM grating to frequency-convert a spatially chirped fundamental wave.A“zerodispersion”4f system maps the spectral contents of ultrabroadband fundamental onto different spatial coordinates in the Fourier plane,where the fundamental is quasi-monochromatic locally in picosecond duration,fundamentally canceling high-order phase mismatch.A fan-out QPM grating characterized by a linear variation of the poling period along the transverse direction exactly supports the QPM of the spatially chirped beam.We theoretically demonstrate the SHG of an 810-nm,12.1-fs pulse into a 405-nm,10.2-fs pulse with a conversion efficiency of 77%.

关键词： nonlinear optics second-harmonic generation few-cycle pulse

Radiation build-up and dissipation in Raman random fiber laser

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Science China(Information Sciences) 2024年第1期67卷 254-260页

作者： Shengtao LIN Zinan WANG Jiaojiao ZHANG Pan WANG Han WU Yifei QI Key Laboratory of Optical Fiber Sensing and Communications University of Electronic Science and Technology of China College of Electronics and Information Engineering Sichuan University

Raman random fiber laser(RRFL) is a complex physical system that arises from the distributed Raman amplification and the intrinsic stochasticity of fiber scattering.The analysis of the underlying lightwave kinetics at steady state has been the focus of considerable interest.However,the transient state,such as the RRFL build-up and dissipation,is particularly important for revealing the lightwave interaction process.Here,we investigate for the first time the RRFL dynamics at the transient state and track the RRFL temporal and spectral evolution theoretically and experimentally.Particularly,with the contribution of random distributed feedback,RRFL build-up exhibits continuous Verhulst logistic growth curves without cavity-related features,which is significantly different from the step-like growth curve of conventional fiber lasers.Furthermore,the radiation build-up duration is inversely related to the pump power,and the spectral evolution of the RRFL undergoes two phases,i.e.,from spectral density increase to spectral broadening.From the steady state to the pump switch-off state,the RRFL output power dissipates immediately,and the remaining Stokes lightwave from the Rayleigh scattering will gradually disappear after one round trip.This work provides new insights into the transient dynamic features of the RRFL.

关键词： random fiber laser stimulated Raman scattering transient phenomenon nonlinear optics łinebreak biological growth dynamics

Plasmon-induced nonlinear response on gold nanoclusters

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Chinese Physics B 2024年第4期33卷 36-39页

作者：宋玉慧曹逸飞黄思晨李凯超杜如海严蕾付正坤张正龙 School of Physics and Information Technology Shaanxi Normal UniversityXi'an 710119China

The plasmon-induced nonlinear response has attracted great attention in micro-nano optics and optoelectronics applications,yet the underlying microscopic mechanism remains elusive.In this study,the nonlinear response of gold nanoclusters when exposed to a femtosecond laser pulse was investigated using time-dependent density functional theory.It was observed that the third-order tunneling current was augmented in plasmonic dimers,owing to a greater number of electrons in the dimer being excited from occupied to unoccupied states.These findings provide profound theoretical insights and enable the realization of accurate regulation and control of nonlinear effects induced by plasmons at the atomic level.

关键词： plasmon nonlinear optics time-dependent density functional theory(TDDFT)

All-optical suppression on the impact of Sun outage in laser satellite communication systems by using a nonlinear semiconductor optical amplifier

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Chinese optics Letters 2024年第2期22卷 76-80页

作者：李晓亮刘荣科范峰 School of Electronics and Information Engineering Beihang UniversityBeijing 100191China Beijing Research Institute of Telemetry Beijing 100094China

We introduce an all-optical approach,optical parametric amplification(OPA)processor to suppress the impact of Sun outage in laser satellite communication systems,which is implemented by only one nonlinear semiconductor optical amplifier driven by both electrical and optical pumps.The optimized OPA processor,with a current of 539 mA and a pump-to-signal ratio of 16 dB,could significantly improve the signal quality by 3.5 dB in experiments for the elevation angle of Sun radiation of 0 rad.The signal quality improvement is observed in the whole range of the elevation angle,confirming the effectiveness of the proposed OPA processor in the field of Sun radiation mitigation.

关键词： nonlinear optics Sun outage laser satellite communication