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 l...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.展开更多
In this paper, considering the Hirota and the Maxwell–Bloch （H-MB） equations which are governed by femtosecond pulse propagation through a two-level doped fiber system, we construct the Darboux transformation of th...In this paper, considering the Hirota and the Maxwell–Bloch （H-MB） equations which are governed by femtosecond pulse propagation through a two-level doped fiber system, we construct the Darboux transformation of this system through a linear eigenvalue problem. Using this Daurboux transformation, we generate multi-soliton, positon, and breather solutions （both bright and dark breathers） of the H-MB equations. Finally, we also construct the rogue wave solutions of the above system.展开更多
Nonlinear dielectric metasurfaces provide a promising approach to control and manipulate frequency conversion optical processes at the nanoscale,thus facilitating both advances in fundamental research and the developm...Nonlinear dielectric metasurfaces provide a promising approach to control and manipulate frequency conversion optical processes at the nanoscale,thus facilitating both advances in fundamental research and the development of new practical applications in photonics,lasing,and sensing.Here,we employ symmetry-broken metasurfaces made of centrosymmetric amorphous silicon for resonantly enhanced second-and third-order nonlinear optical response.Exploiting the rich physics of optical quasi-bound states in the continuum and guided mode resonances,we comprehensively study through rigorous numerical calculations the relative contribution of surface and bulk effects to second-harmonic generation(SHG)and the bulk contribution to third-harmonic generation(THG) from the meta-atoms.Next,we experimentally achieve optical resonances with high quality factors,which greatly boosts light-matter interaction,resulting in about 550 times SHG enhancement and nearly 5000-fold increase of THG.A good agreement between theoretical predictions and experimental measurements is observed.To gain deeper insights into the physics of the investigated nonlinear optical processes,we further numerically study the relation between nonlinear emission and the structural asymmetry of the metasurface and reveal that the generated harmonic signals arising from linear sharp resonances are highly dependent on the asymmetry of the meta-atoms.Our work suggests a fruitful strategy to enhance the harmonic generation and effectively control different orders of harmonics in all-dielectric metasurfaces,enabling the development of efficient active photonic nanodevices.展开更多
Recent progresses about optical pumped tunable terahertz （THz） sources are interviewed, including THz parametric oscillation （TPO） and difference frequency generation （DFG）. We develop high efficiency and high p...Recent progresses about optical pumped tunable terahertz （THz） sources are interviewed, including THz parametric oscillation （TPO） and difference frequency generation （DFG）. We develop high efficiency and high power surface-emitted TPO, as well as DFG with nonlinear crystals. A novel scheme for the high efficiency DFG source based on the Cherenkov phase-matching technology is comprehensively investigated in both bulk crystals. The widely tunable optical THz radiation is also researched based on the organic nonlinear 4-N,N-dimethylamino-4＇-N＇- methylstilbazolium 2,4,6-trimethylbenzenesulfonate （DSTMS） crystal.展开更多
The ultrashort lasers working in pulse-burst mode reveal great machining performance in recent years. The number of pulses in bursts effects greatly on the removal rate and roughness. To generate a more equal amplitud...The ultrashort lasers working in pulse-burst mode reveal great machining performance in recent years. The number of pulses in bursts effects greatly on the removal rate and roughness. To generate a more equal amplitude of pulses in burst with linear polarization output and time gap adjustable, we propose a new method by the harmonic beam combining(HBC).The beam combining is commonly used in adding pulses into the output beam while maintaining the pulse waveform and beam quality. In the HBC, dichroic mirrors are used to combine laser pulses of fundamental wave(FW) into harmonic wave(HW), and nonlinear crystals are used to convert the FW into HW. Therefore, HBC can add arbitrarily more HW pulses to generate pulse-burst in linear polarization with simple structure. The amplitude of each pulse in bursts can be adjusted the same to increase the stability of the burst, the time gap of each pulse can be adjusted precisely by proper time delay. Because HBC adds pulses sequentially, the peak power density of the burst is the same as each pulse, pulses can be combined without concern of back-conversion which often occurs in high peak power density. In the demonstration, the extendibility of HBC was verified by combining two beams with a third beam. The combined efficiency rates were larger than 99%, and the beam quality of each beam was maintained at M^(2)≈1.4.展开更多
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 ...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.展开更多
Light beams carrying multiple orbital angular momentum(OAM)states,which can be realized by the structured media with phase singularities,have attracted great attentions in the fields of high dimensional optical inform...Light beams carrying multiple orbital angular momentum(OAM)states,which can be realized by the structured media with phase singularities,have attracted great attentions in the fields of high dimensional optical information processing.Alternatively,a simple uniaxial crystal can be used to simultaneously generate four OAM states of light through the second harmonic generation and cascaded optical spin-orbit interaction(SOI)processes.However,two of the OAM states realized in the crystal are very weak and limit the practical applications.Here,we aim to circumvent this constraint by using the sequential optical SOI processes in two crystals with threefold rotational symmetry.Four angular momentum states of the fundamental waves are prepared after the first crystal and then are utilized to generate the corresponding second harmonic waves(SHWs)with opposite spin and doubled OAM in the second crystal.Further through a sequential SOI process,totally eight angular momentum states of the SHWs with nearly equal energy are experimentally observed.The proposed methodology may find potential applications in optical communications,parallel optical computing,optical manipulation and so on.展开更多
A Weyl node is characterized by its chirality and tilt.We develop a theory of how nth-order nonlinear optical conductivity behaves under transformations of anisotropic tensor and tilt, which clarifies how chirality-de...A Weyl node is characterized by its chirality and tilt.We develop a theory of how nth-order nonlinear optical conductivity behaves under transformations of anisotropic tensor and tilt, which clarifies how chirality-dependent and-independent parts of optical conductivity transform under the reversal of tilt and chirality.Built on this theory, we propose ferromagnetic Mn Bi2Te4as a magnetoelectrically regulated, terahertz optical device, by magnetoelectrically switching the chiralitydependent and-independent DC photocurrents.These results are useful for creating nonlinear optical devices based on the topological Weyl semimetals.展开更多
Cyclo[18]carbon has received considerable attention thanks to its novel geometric configuration and special electronic structure.Superalkalis have low ionization energy.Doping a superalkali in cyclo[18]carbon is an ef...Cyclo[18]carbon has received considerable attention thanks to its novel geometric configuration and special electronic structure.Superalkalis have low ionization energy.Doping a superalkali in cyclo[18]carbon is an effective method to improve the optical properties of the system because considerable electron transfer occurs.In this paper,the geometry,bonding properties,electronic structure,absorption spectrum,and nonlinear optical(NLO)properties of superalkaline M_(3)O(M=Li,Na)-doped cyclo[18]carbon were studied by using density functional theory.M_(3)O and the C_(18) rings are not coplanar.The C_(18) ring still exhibits alternating long and short bonds.The charge transfer between M_(3)O and C_(18) forms stable[M_(3)O]+[C_(18)]-ionic complexes.C_(18)M_(3)O(M=Li,Na)shows striking optical nonlinearity,i.e.,their first-and second-order hyperpolarizability(βvec andγ||)increase considerably atλ=1907 nm and 1460 nm.展开更多
The study of nonlinear optical responses in the mid-infrared(mid-IR)regime is essential for advancing ultrafast mid-IR laser applications.However,nonlinear optical effects under mid-IR excitation are rarely reported d...The study of nonlinear optical responses in the mid-infrared(mid-IR)regime is essential for advancing ultrafast mid-IR laser applications.However,nonlinear optical effects under mid-IR excitation are rarely reported due to the lack of suitable nonlinear optical materials.The natural van derWaals heterostructure franckeite,known for its narrow bandgap and stability in air,shows great potential for developing mid-IR nonlinear optical devices.We have experimentally demonstrated that layered franckeite exhibits a broadband wavelength-dependent nonlinear optical response in the mid-IR spectral region.Franckeite nanosheets were prepared using a liquid-phase exfoliation method,and their nonlinear optical response was characterized in the spectral range of 3000 nm to 5000 nm.The franckeite nanosheets exhibit broadband wavelengthdependent third-order nonlinearities,with nonlinear absorption and refraction coefficients estimated to be about 10^(-7)cm/W and 10^(-11)cm^(2)/W,respectively.Additionally,a passively Q-switched fluoride fiber laser operating around a wavelength of 2800 nm was achieved,delivering nanosecond pulses with a signal-to-noise ratio of 43.6 dB,based on the nonlinear response of franckeite.These findings indicate that layered franckeite possesses broadband nonlinear optical characteristics in the mid-IR region,potentially enabling new possibilities for mid-IR photonic devices.展开更多
Off-axis-rotating elliptical Gaussian beams(Oare GB)oblique incidence in strong nonlocal medium exhibit novel propagation properties.The analytical expressions of semi-axial beam widths,and center-of-mass trajectory e...Off-axis-rotating elliptical Gaussian beams(Oare GB)oblique incidence in strong nonlocal medium exhibit novel propagation properties.The analytical expressions of semi-axial beam widths,and center-of-mass trajectory equations for transmitting off-axis-rotating elliptical Gaussian beams in strong nonlocal media are obtained using the ABCD transfer matrix method.The study revealed that the trajectory of the mass's center in the cross-section can be controlled by changing the sizes of the Oare GB parameters c,d,ζ,and f.The gradient force of the light field causes the spot region to form a spatial potential well in the media,and this spatial potential well can effectively capture nanoparticles.The particles captured by the light field can move along with the beam,realizing the effective manipulation of the particle trajectory.These laws may be applied to modulating the propagation path of light beams and optical tweezer technology.展开更多
Graphene has excellent thirdorder nonlinear optical(NLO)properties due to its unique electronic band structure and wideband gap tunability.This paper focuses on the research progress of graphene and its composite mate...Graphene has excellent thirdorder nonlinear optical(NLO)properties due to its unique electronic band structure and wideband gap tunability.This paper focuses on the research progress of graphene and its composite materials in nonlinear optics in recent years.In this review,recent results on graphene(or graphene oxide)-metal nanoparticles(G-MNPs),graphene-metal-oxide nanoparticles(G-MONPs),graphene-metal sulfide nanoparticles(G-MSNPs),and graphene-organic molecular composites(G-OM)have been discussed.In addition,the enhancement mechanism of nonlinear absorption(NLA)and optical limiting(OL)have also been covered.展开更多
A thermal lens technique is adopted using a single modulated continuous wave （cw） 532-nm laser beam to evaluate the nonlinear refractive index n2, and the thermo-optic coefficient dn/dT, in polymer Poly （1-naphthyl...A thermal lens technique is adopted using a single modulated continuous wave （cw） 532-nm laser beam to evaluate the nonlinear refractive index n2, and the thermo-optic coefficient dn/dT, in polymer Poly （1-naphthyl methacrylate） （P-1-NM） dissolved in chloroform, tetrahydrofuran （THF）, and dimethyl sulfoxide （DMSO） solvents. The results are compared with Z-scan and diffraction ring techniques. The comparison reveals the effectiveness and the simplicity of the TTL modulation technique. The physical origin is discussed for the obtained results.展开更多
The operational parameters including the polarization controlling and the pump power in a nonlinear polarization rotation-based passively mode-locked fiber laser are studied in this paper.The carrier rate equations of...The operational parameters including the polarization controlling and the pump power in a nonlinear polarization rotation-based passively mode-locked fiber laser are studied in this paper.The carrier rate equations of the activated erbium-doped fiber are first employed together with the nonlinear Shro¨dinger equations to reveal the relation between the operational parameters and the output state of the passively mode-locked fiber laser.The numerical and experimental results demonstrate that the output state of the mode-locked laser varies with the polarization controlling and the pump power.The periodicity of the polarization controlling is observed.With given pump power,there exists a set of polarization controlling under which the ultra-short pulse can be generated.With given polarization controlling,the mode-locked state can be maintained generally except for some particular values of pump power.Three shapes of the output optical spectra from the fiber cavity can be identified when the pump power changes.The results in this paper provide a comprehensive insight into the operation of the nonlinear polarization rotation-based passively mode-locked fiber laser.展开更多
Nonlinear optics is an important research direction with various applications in laser manufacturing,fabrication of nano-structure,sensor design,optoelectronics,biophotonics,quantum optics,etc.Nonlinear optical materi...Nonlinear optics is an important research direction with various applications in laser manufacturing,fabrication of nano-structure,sensor design,optoelectronics,biophotonics,quantum optics,etc.Nonlinear optical materials are the funda-mental building blocks,which are critical for broad fields ranging from scientific research,industrial production,to military.Nanoparticles demonstrate great potential due to their flexibility to be engineered and their enhanced nonlinear optical properties superior to their bulk counterparts.Synthesis of nanoparticles by laser ablation proves to be a green,efficient,and universal physical approach,versatile for fast one-step synthesis and potential mass production.In this review,the development and latest progress of nonlinear optical nanoparticles synthesized by laser ablation are summarized,which demonstrates its capability for enhanced performance and multiple functions.The theory of optical nonlinear absorption,experimental process of laser ablation,applications,and outlooks are covered.Potential for nanoparticle systems is yet to be fully discovered,which offers opportunities to make various types of next-generation functional devices.展开更多
We develop a nonlinear beam propagation method for signal generation in inhomogeneous medium for wide-field nonlinear wave mixing microscope. Experimental results performed in wide-field coherent anti-Stokes Raman ima...We develop a nonlinear beam propagation method for signal generation in inhomogeneous medium for wide-field nonlinear wave mixing microscope. Experimental results performed in wide-field coherent anti-Stokes Raman imaging have shown good agreement with the developed theory.展开更多
We report on controllable pulse shaping in a Yb-doped stretched-pulse fiber laser followed by a high-power chirped pulse amplifier. We demonstrate that the pulses after an extra-cavity grating pair change their intens...We report on controllable pulse shaping in a Yb-doped stretched-pulse fiber laser followed by a high-power chirped pulse amplifier. We demonstrate that the pulses after an extra-cavity grating pair change their intensity profile from Lorentz to Gaussian and then to sech2 shapes by adjusting the intra-cavity polarization through a quarter-wave plate inside the fiber laser cavity. The laser pulses with different pulse shapes exhibit pulse-to-pulse amplitude fluctuation of -- 1.02%, while the sech2-shaped pulse train is provided with a more stable free-running repetition rate as a result of the stronger self-phase modulation in the fiber laser cavity than Lorentz- and Gaussian-shaped pulse trains.展开更多
Owing to the enormously enhanced oscillating wave,a minute variation of the incident light intensity will give rise to a change in the dielectric constant of the Kerr nonlinear medium and lead to a bistable reflection...Owing to the enormously enhanced oscillating wave,a minute variation of the incident light intensity will give rise to a change in the dielectric constant of the Kerr nonlinear medium and lead to a bistable reflection with an ultra-low threshold intensity,which is closely related to the angle of incidence and the thickness of the Kerr nonlinear medium.The criterion for the existence of optical bistability is derived.Our bistability scheme is simple and not limited to the TM-polarization.展开更多
Utilizing the linear-stability analysis, this paper analytically investigates and calculates the condition and gain spectra of cross-phase modulation instability in optical fibres in the ease of exponential saturable ...Utilizing the linear-stability analysis, this paper analytically investigates and calculates the condition and gain spectra of cross-phase modulation instability in optical fibres in the ease of exponential saturable nonlinearity and high-order dispersion. The results show that, the modulation instability characteristics here are similar to those of conventional saturable nonlinearity and Kerr nonlinearity. That is to say, when the fourth-order dispersion has the same sign as that of the second-order one, a new gain spectral region called the second one which is far away from the zero point may appear. The existence of the exponential saturable nonlinearity will make the spectral width as well as the peak gain of every spectral region increase with the input powers before decrease. Namely, for every spectral regime, this may lead to a unique value of peak gain and spectral width for two different input powers. In comparison with the case of conventional saturable nonlinearity, however, when the other parameters are the same, the variations of the spectral width and the peak gain with the input powers will be faster in case of exponential saturable nonlinearity.展开更多
The generation characteristics of nonlinear optical signals and their multi-dimensional modulation at micro-nano scale have become a prominent research area in nanophotonics,and also the key to developing various nove...The generation characteristics of nonlinear optical signals and their multi-dimensional modulation at micro-nano scale have become a prominent research area in nanophotonics,and also the key to developing various novel nonlinear photonics devices.In recent years,the demand for higher nonlinear conversion efficiency and device integration has led to the rapid progress of hybrid nonlinear metasurfaces composed of nanostructures and nonlinear materials.As a joint platform of stable wavefront modulation,nonlinear metasurface and efficient frequency conversion,hybrid nonlinear metasurfaces offer a splendid opportunity for developing the next-generation of multipurpose flat-optics devices.This article provides a comprehensive review of recent advances in hybrid nonlinear metasurfaces for light-field modulation.The advantages of hybrid systems are discussed from the perspectives of multifunctional light-field modulation,valleytronic modulation,and quantum technologies.Finally,the remaining challenges of hybrid metasurfaces are summarized and future developments are also prospected.展开更多
文摘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.
基金Project supported by the Natural Science Foundation of Zhejiang Province of China (Grant No. LY12A01007)the National Natural Science Foundation of China (Grant Nos. 11201251, 10971109, and 11271210)+1 种基金K. C. Wong Magna Fund in Ningbo Universitythe DST,DAE-BRNS, UGC, and CSIR, Government of India, for the financial support through major projects
文摘In this paper, considering the Hirota and the Maxwell–Bloch （H-MB） equations which are governed by femtosecond pulse propagation through a two-level doped fiber system, we construct the Darboux transformation of this system through a linear eigenvalue problem. Using this Daurboux transformation, we generate multi-soliton, positon, and breather solutions （both bright and dark breathers） of the H-MB equations. Finally, we also construct the rogue wave solutions of the above system.
基金supported by the Australian Research Council(Grant No.DP210101292)the International Technology Center Indo-Pacific (ITC IPAC) via Army Research Office (contract FA520923C0023)。
文摘Nonlinear dielectric metasurfaces provide a promising approach to control and manipulate frequency conversion optical processes at the nanoscale,thus facilitating both advances in fundamental research and the development of new practical applications in photonics,lasing,and sensing.Here,we employ symmetry-broken metasurfaces made of centrosymmetric amorphous silicon for resonantly enhanced second-and third-order nonlinear optical response.Exploiting the rich physics of optical quasi-bound states in the continuum and guided mode resonances,we comprehensively study through rigorous numerical calculations the relative contribution of surface and bulk effects to second-harmonic generation(SHG)and the bulk contribution to third-harmonic generation(THG) from the meta-atoms.Next,we experimentally achieve optical resonances with high quality factors,which greatly boosts light-matter interaction,resulting in about 550 times SHG enhancement and nearly 5000-fold increase of THG.A good agreement between theoretical predictions and experimental measurements is observed.To gain deeper insights into the physics of the investigated nonlinear optical processes,we further numerically study the relation between nonlinear emission and the structural asymmetry of the metasurface and reveal that the generated harmonic signals arising from linear sharp resonances are highly dependent on the asymmetry of the meta-atoms.Our work suggests a fruitful strategy to enhance the harmonic generation and effectively control different orders of harmonics in all-dielectric metasurfaces,enabling the development of efficient active photonic nanodevices.
基金supported by the National High Technology Research and Development Program of China(863)under Grant No.2011AA010205National Natural Science Foundation of China under Grant No.6117201061101058,61107086,and 61275120+2 种基金the CAEP THz Science and Technology Foundation under Grant No.CAEPTHZ201201 and CAEPTHZ201304the Natural Science Foundation of Tianjin under Grant No.11JCYBJC01100 and 13ZCZDSF02300the Specialized Research Fund for the Doctoral Program of Higher Education under Grant No.20120032110053
文摘Recent progresses about optical pumped tunable terahertz （THz） sources are interviewed, including THz parametric oscillation （TPO） and difference frequency generation （DFG）. We develop high efficiency and high power surface-emitted TPO, as well as DFG with nonlinear crystals. A novel scheme for the high efficiency DFG source based on the Cherenkov phase-matching technology is comprehensively investigated in both bulk crystals. The widely tunable optical THz radiation is also researched based on the organic nonlinear 4-N,N-dimethylamino-4＇-N＇- methylstilbazolium 2,4,6-trimethylbenzenesulfonate （DSTMS） crystal.
基金Project supported by Youth Innovation Promotion Association of the Chinese Academy of Sciences (Grant No.2020029)。
文摘The ultrashort lasers working in pulse-burst mode reveal great machining performance in recent years. The number of pulses in bursts effects greatly on the removal rate and roughness. To generate a more equal amplitude of pulses in burst with linear polarization output and time gap adjustable, we propose a new method by the harmonic beam combining(HBC).The beam combining is commonly used in adding pulses into the output beam while maintaining the pulse waveform and beam quality. In the HBC, dichroic mirrors are used to combine laser pulses of fundamental wave(FW) into harmonic wave(HW), and nonlinear crystals are used to convert the FW into HW. Therefore, HBC can add arbitrarily more HW pulses to generate pulse-burst in linear polarization with simple structure. The amplitude of each pulse in bursts can be adjusted the same to increase the stability of the burst, the time gap of each pulse can be adjusted precisely by proper time delay. Because HBC adds pulses sequentially, the peak power density of the burst is the same as each pulse, pulses can be combined without concern of back-conversion which often occurs in high peak power density. In the demonstration, the extendibility of HBC was verified by combining two beams with a third beam. The combined efficiency rates were larger than 99%, and the beam quality of each beam was maintained at M^(2)≈1.4.
基金Project supported by the National Key R&D Program of China (Grant Nos.2020YFA0211300 and 2021YFA1201500)the National Natural Science Foundation of China (Grant Nos.U22A6005,92150110,12074237,and 12304426)+2 种基金the Natural Science Foundation of Shaanxi Province (Grant No.2024JC-JCQN-07)the Fundamental Science Foundation of Shaanxi (Grant No.22JSZ010)the Fundamental Research Funds for Central Universities (Grant Nos.GK202201012 and GK202308001)。
文摘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.
基金supported by National Natural Science Foundation of China Grants(91950114&12161141010)National Key Technologies R&D Program of China(2022YFA1404301)+1 种基金Guangdong Provincial Innovation and Entrepreneurship Project Grant(2017ZT07C071)Natural Science Foundation of Shenzhen Innovation Commission Grant(JCYJ20200109140808088).
文摘Light beams carrying multiple orbital angular momentum(OAM)states,which can be realized by the structured media with phase singularities,have attracted great attentions in the fields of high dimensional optical information processing.Alternatively,a simple uniaxial crystal can be used to simultaneously generate four OAM states of light through the second harmonic generation and cascaded optical spin-orbit interaction(SOI)processes.However,two of the OAM states realized in the crystal are very weak and limit the practical applications.Here,we aim to circumvent this constraint by using the sequential optical SOI processes in two crystals with threefold rotational symmetry.Four angular momentum states of the fundamental waves are prepared after the first crystal and then are utilized to generate the corresponding second harmonic waves(SHWs)with opposite spin and doubled OAM in the second crystal.Further through a sequential SOI process,totally eight angular momentum states of the SHWs with nearly equal energy are experimentally observed.The proposed methodology may find potential applications in optical communications,parallel optical computing,optical manipulation and so on.
基金Project supported by the National Key R&D Program of China (Grant Nos.2018YFA, 0305601, and 2021YFA1400100)the National Natural Science Foundation of China (Grant Nos.12274003, 11725415, and 11934001)the Innovation Program for Quantum Science and Technology (Grant No.2021ZD0302600)。
文摘A Weyl node is characterized by its chirality and tilt.We develop a theory of how nth-order nonlinear optical conductivity behaves under transformations of anisotropic tensor and tilt, which clarifies how chirality-dependent and-independent parts of optical conductivity transform under the reversal of tilt and chirality.Built on this theory, we propose ferromagnetic Mn Bi2Te4as a magnetoelectrically regulated, terahertz optical device, by magnetoelectrically switching the chiralitydependent and-independent DC photocurrents.These results are useful for creating nonlinear optical devices based on the topological Weyl semimetals.
基金Project supported by the Natural Science Foundation of Anhui Province(Grant No.1908085MA12)the National Natural Science Foundation of China(Grant No.21703222)。
文摘Cyclo[18]carbon has received considerable attention thanks to its novel geometric configuration and special electronic structure.Superalkalis have low ionization energy.Doping a superalkali in cyclo[18]carbon is an effective method to improve the optical properties of the system because considerable electron transfer occurs.In this paper,the geometry,bonding properties,electronic structure,absorption spectrum,and nonlinear optical(NLO)properties of superalkaline M_(3)O(M=Li,Na)-doped cyclo[18]carbon were studied by using density functional theory.M_(3)O and the C_(18) rings are not coplanar.The C_(18) ring still exhibits alternating long and short bonds.The charge transfer between M_(3)O and C_(18) forms stable[M_(3)O]+[C_(18)]-ionic complexes.C_(18)M_(3)O(M=Li,Na)shows striking optical nonlinearity,i.e.,their first-and second-order hyperpolarizability(βvec andγ||)increase considerably atλ=1907 nm and 1460 nm.
基金supported by the National Natural Science Foundation of China(Grant No.61975055)the Natural Science Foundation of Hunan Province,China(Grant No.2023JJ30165)+1 种基金the Natural Science Foundation of Shandong Province,China(Grant No.ZR2022QF005)the Doctoral Fund of University of Heze(Grant No.XY22BS14).
文摘The study of nonlinear optical responses in the mid-infrared(mid-IR)regime is essential for advancing ultrafast mid-IR laser applications.However,nonlinear optical effects under mid-IR excitation are rarely reported due to the lack of suitable nonlinear optical materials.The natural van derWaals heterostructure franckeite,known for its narrow bandgap and stability in air,shows great potential for developing mid-IR nonlinear optical devices.We have experimentally demonstrated that layered franckeite exhibits a broadband wavelength-dependent nonlinear optical response in the mid-IR spectral region.Franckeite nanosheets were prepared using a liquid-phase exfoliation method,and their nonlinear optical response was characterized in the spectral range of 3000 nm to 5000 nm.The franckeite nanosheets exhibit broadband wavelengthdependent third-order nonlinearities,with nonlinear absorption and refraction coefficients estimated to be about 10^(-7)cm/W and 10^(-11)cm^(2)/W,respectively.Additionally,a passively Q-switched fluoride fiber laser operating around a wavelength of 2800 nm was achieved,delivering nanosecond pulses with a signal-to-noise ratio of 43.6 dB,based on the nonlinear response of franckeite.These findings indicate that layered franckeite possesses broadband nonlinear optical characteristics in the mid-IR region,potentially enabling new possibilities for mid-IR photonic devices.
基金Project supported by the National Natural Science Foundation of China(Grant No.62075047)the Natural Science Foundation of Guangxi Zhuang Autonomous Region,China(Grant No.2020GXNSFDA297019)。
文摘Off-axis-rotating elliptical Gaussian beams(Oare GB)oblique incidence in strong nonlocal medium exhibit novel propagation properties.The analytical expressions of semi-axial beam widths,and center-of-mass trajectory equations for transmitting off-axis-rotating elliptical Gaussian beams in strong nonlocal media are obtained using the ABCD transfer matrix method.The study revealed that the trajectory of the mass's center in the cross-section can be controlled by changing the sizes of the Oare GB parameters c,d,ζ,and f.The gradient force of the light field causes the spot region to form a spatial potential well in the media,and this spatial potential well can effectively capture nanoparticles.The particles captured by the light field can move along with the beam,realizing the effective manipulation of the particle trajectory.These laws may be applied to modulating the propagation path of light beams and optical tweezer technology.
基金Project supported by the National Natural Science Foundation of China(Grant No.11375136).
文摘Graphene has excellent thirdorder nonlinear optical(NLO)properties due to its unique electronic band structure and wideband gap tunability.This paper focuses on the research progress of graphene and its composite materials in nonlinear optics in recent years.In this review,recent results on graphene(or graphene oxide)-metal nanoparticles(G-MNPs),graphene-metal-oxide nanoparticles(G-MONPs),graphene-metal sulfide nanoparticles(G-MSNPs),and graphene-organic molecular composites(G-OM)have been discussed.In addition,the enhancement mechanism of nonlinear absorption(NLA)and optical limiting(OL)have also been covered.
文摘A thermal lens technique is adopted using a single modulated continuous wave （cw） 532-nm laser beam to evaluate the nonlinear refractive index n2, and the thermo-optic coefficient dn/dT, in polymer Poly （1-naphthyl methacrylate） （P-1-NM） dissolved in chloroform, tetrahydrofuran （THF）, and dimethyl sulfoxide （DMSO） solvents. The results are compared with Z-scan and diffraction ring techniques. The comparison reveals the effectiveness and the simplicity of the TTL modulation technique. The physical origin is discussed for the obtained results.
基金Project supported by the National Natural Science Foundation of China (Grant Nos. 60972017,60978007,and 61177067)
文摘The operational parameters including the polarization controlling and the pump power in a nonlinear polarization rotation-based passively mode-locked fiber laser are studied in this paper.The carrier rate equations of the activated erbium-doped fiber are first employed together with the nonlinear Shro¨dinger equations to reveal the relation between the operational parameters and the output state of the passively mode-locked fiber laser.The numerical and experimental results demonstrate that the output state of the mode-locked laser varies with the polarization controlling and the pump power.The periodicity of the polarization controlling is observed.With given pump power,there exists a set of polarization controlling under which the ultra-short pulse can be generated.With given polarization controlling,the mode-locked state can be maintained generally except for some particular values of pump power.Three shapes of the output optical spectra from the fiber cavity can be identified when the pump power changes.The results in this paper provide a comprehensive insight into the operation of the nonlinear polarization rotation-based passively mode-locked fiber laser.
基金This work was supported by Advanced Remanufacturing and Technology Centre(ARTC)under its RIE2020 Advanced Manufacturing and Engineering(AME)IAF PP Grant(No.A19C2a0019)Ministry of Education-Singapore(MOE2019-T2-2-147).
文摘Nonlinear optics is an important research direction with various applications in laser manufacturing,fabrication of nano-structure,sensor design,optoelectronics,biophotonics,quantum optics,etc.Nonlinear optical materials are the funda-mental building blocks,which are critical for broad fields ranging from scientific research,industrial production,to military.Nanoparticles demonstrate great potential due to their flexibility to be engineered and their enhanced nonlinear optical properties superior to their bulk counterparts.Synthesis of nanoparticles by laser ablation proves to be a green,efficient,and universal physical approach,versatile for fast one-step synthesis and potential mass production.In this review,the development and latest progress of nonlinear optical nanoparticles synthesized by laser ablation are summarized,which demonstrates its capability for enhanced performance and multiple functions.The theory of optical nonlinear absorption,experimental process of laser ablation,applications,and outlooks are covered.Potential for nanoparticle systems is yet to be fully discovered,which offers opportunities to make various types of next-generation functional devices.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11174019,61322509 and 11121091)the National Basic Research Program of China(Grant No.2013CB921904)
文摘We develop a nonlinear beam propagation method for signal generation in inhomogeneous medium for wide-field nonlinear wave mixing microscope. Experimental results performed in wide-field coherent anti-Stokes Raman imaging have shown good agreement with the developed theory.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11274115 and 10990101)the National Key Project for Basic Research of China(Grant No.2011CB808105)+2 种基金the National Key Scientific Instrument Project,China(Grant No.2012YQ150092)the Natural Science Foundation of Shanghai,China(Grant No.11ZR1410900)the Innovation Program of Shanghai Municipal Education Commission,China(Grant No.2014Z10269011)
文摘We report on controllable pulse shaping in a Yb-doped stretched-pulse fiber laser followed by a high-power chirped pulse amplifier. We demonstrate that the pulses after an extra-cavity grating pair change their intensity profile from Lorentz to Gaussian and then to sech2 shapes by adjusting the intra-cavity polarization through a quarter-wave plate inside the fiber laser cavity. The laser pulses with different pulse shapes exhibit pulse-to-pulse amplitude fluctuation of -- 1.02%, while the sech2-shaped pulse train is provided with a more stable free-running repetition rate as a result of the stronger self-phase modulation in the fiber laser cavity than Lorentz- and Gaussian-shaped pulse trains.
基金Projected supported by the Open Fund by State Key Laboratory of Advanced Optical Communication Systems and Networks(Grant No.2017GZKF18)the National Natural Science Foundation of China(Grant Nos.12064017,61765008,11764020,11864017,11804133,and 51567011)+3 种基金the Jiangxi Provincial Natural Science Foundation(Grant No.20181BAB206034)the Fundamental Research Funds for the Central Universities of China(Grant No.2017B14914),the Postdoctoral Science Foundation of China(Grant No.2016M601586)the Science and Technology Project of Changzhou(Grant No.CJ20180048)Scientific Research Fund of Jiangxi Provincial Education Department(Grant Nos.GJJ150313,GJJ160273,and GJJ170184).
文摘Owing to the enormously enhanced oscillating wave,a minute variation of the incident light intensity will give rise to a change in the dielectric constant of the Kerr nonlinear medium and lead to a bistable reflection with an ultra-low threshold intensity,which is closely related to the angle of incidence and the thickness of the Kerr nonlinear medium.The criterion for the existence of optical bistability is derived.Our bistability scheme is simple and not limited to the TM-polarization.
基金Project supported by the Key Program of the Natural Science Foundation of Sichuan Provincial Education Department (Grant No. 2006A124)the Fundamental Application Research Project of the Department of Science & Technology of Sichuan Province (Grant No. 05JY029-084)
文摘Utilizing the linear-stability analysis, this paper analytically investigates and calculates the condition and gain spectra of cross-phase modulation instability in optical fibres in the ease of exponential saturable nonlinearity and high-order dispersion. The results show that, the modulation instability characteristics here are similar to those of conventional saturable nonlinearity and Kerr nonlinearity. That is to say, when the fourth-order dispersion has the same sign as that of the second-order one, a new gain spectral region called the second one which is far away from the zero point may appear. The existence of the exponential saturable nonlinearity will make the spectral width as well as the peak gain of every spectral region increase with the input powers before decrease. Namely, for every spectral regime, this may lead to a unique value of peak gain and spectral width for two different input powers. In comparison with the case of conventional saturable nonlinearity, however, when the other parameters are the same, the variations of the spectral width and the peak gain with the input powers will be faster in case of exponential saturable nonlinearity.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.12274157,12274334,91850113,12021004,and 11904271)the Natural Science Foundation of Hubei Province of China(Grant No.2023AFA076)the Basic and Applied Basic Research Major Program of Guangdong Province of China(Grant No.2019B030302003)。
文摘The generation characteristics of nonlinear optical signals and their multi-dimensional modulation at micro-nano scale have become a prominent research area in nanophotonics,and also the key to developing various novel nonlinear photonics devices.In recent years,the demand for higher nonlinear conversion efficiency and device integration has led to the rapid progress of hybrid nonlinear metasurfaces composed of nanostructures and nonlinear materials.As a joint platform of stable wavefront modulation,nonlinear metasurface and efficient frequency conversion,hybrid nonlinear metasurfaces offer a splendid opportunity for developing the next-generation of multipurpose flat-optics devices.This article provides a comprehensive review of recent advances in hybrid nonlinear metasurfaces for light-field modulation.The advantages of hybrid systems are discussed from the perspectives of multifunctional light-field modulation,valleytronic modulation,and quantum technologies.Finally,the remaining challenges of hybrid metasurfaces are summarized and future developments are also prospected.
