The emergence of hybrid nanostructures has paved a novel path for the development of nanotechnology and next-generation quantum devices.In this study,we report a remarkable enhancement of nonlinear diffraction achieve...The emergence of hybrid nanostructures has paved a novel path for the development of nanotechnology and next-generation quantum devices.In this study,we report a remarkable enhancement of nonlinear diffraction achieved within a hybrid artificial molecule consisting of a semiconductor quantum dot(SQD)and a metal nanoparticle(MNP).Our findings reveal that the optical nonlinear properties of the hybrid system can be substantially enhanced due to the plasmon resonance of MNP.Specifically,reducing the interparticle distance and the SQD's size while increasing the MNP's size leads to a significant enhancement in the nonlinear phase modulation of the hybrid system.Meanwhile,the absorption spectra exhibit a redshift accompanied by linewidth broadening under the SQD-MNP coupling interaction controlled by geometric parameters,indicating plasmon-exciton energy transfer.On this basis,it is validated that the enhanced nonlinear phase modulation greatly improves the self-imaging visibility and the signal-to-noise ratio,and extends the near-field pattern over more Talbot lengths.We also demonstrate that the far-field diffraction efficiency is tunable via the coupling interaction between the artificial molecule and external fields,which is determined by the geometric structure,photon detuning,and Rabi frequency.For instance,the first-order diffraction efficiency can be increased from 39.58%to 55%if the geometric parameters of the hybrid system satisfy the threshold in non-resonance conditions.Such plasmon-enhanced optical lattices show potential for applications in all-optical modulators and all-optical switches operating at few-photon levels,and may also afford a novel perspective for the design and development of nanophotonics circuits and topological photonic devices.展开更多
When a laser beam is incident on a nonlinear grating with a laterally modulated second-order nonlinear coefficient,nonlinear diffraction of the noncollinear second-harmonic generation(SHG)signal occurs,with Raman–Nat...When a laser beam is incident on a nonlinear grating with a laterally modulated second-order nonlinear coefficient,nonlinear diffraction of the noncollinear second-harmonic generation(SHG)signal occurs,with Raman–Nath nonlinear diffraction(NRND)being a prominent example.As these SHG NRND processes involve coupling between the fundamental-wave pump laser vectorial field and the SHG laser vectorial field through the second-order nonlinearity secondrank tensor of the nonlinear crystal,the nonlinear interaction between light and the nonlinear grating can be manipulated by adjusting the polarization state of the pump laser.In this paper,we derive the relationship between the polarization state of the incident light and the generated nonlinear diffraction signal based on the nonlinear coupled wave equation and experimentally validate the predicted diffraction characteristics.The results show that the optical properties of each order of NRND are highly sensitive to the polarization angle of the incident pump laser beam.展开更多
When a pump laser beam strikes the surface of a nonlinear crystal with modulated second-order nonlinearity,various nonlinear diffraction phenomena occur,with nonlinear Raman–Nath diffraction(NRND)being a prominent ex...When a pump laser beam strikes the surface of a nonlinear crystal with modulated second-order nonlinearity,various nonlinear diffraction phenomena occur,with nonlinear Raman–Nath diffraction(NRND)being a prominent example.In this study,we use an 800-nm Ti:sapphire femtosecond laser beam to pump the surface of a periodically poled lithium niobate(PPLN)crystal thin-plate nonlinear grating.By rotating the crystal,we change the incidence angle and observe and measure the exit angle,polarization,and power of NRND spots on the other side of the crystal.The experiment shows that NRND characteristics are highly sensitive to the incidence angle of the pump laser beam,which are consistent with the theoretical prediction.We expect that this research will advance the understanding of nonlinear diffraction and provide valuable insights for nonlinear optical interaction in complicated geometric and physical configurations.展开更多
We present in this paper a semi-analytical solution for second-order wave diffraction by a vertical circular cylinder in bichromatic waves. On the base of the usual assumption of an irrotational flow, the wave-diffrac...We present in this paper a semi-analytical solution for second-order wave diffraction by a vertical circular cylinder in bichromatic waves. On the base of the usual assumption of an irrotational flow, the wave-diffraction problems at second-order sum-frequency and difference-frequency are considered. The corresponding second-order diffraction potentials are decomposed into three parts, these are associated with the second-order incident wave, the quadratic forcing terras on the free-surface due to the first-order potential, and the linearised free-wave component resulting from the boundary condition on the body surface. A particular solution which exactly satisfies the inhomogeneous free-surface condition has been derived. Numerical results for the quadratic transfer functions of the second-order force components are given, and are compared with those obtained using numerical solutions (Kim & Yue, 1990,Moubayed & Williams 1995). These quadratic functions are useful in calculating the exciting forces on a circular cylinder of large dimension, fixed in irregular wave fields.展开更多
An analytical method for the efficient investigation of the nonlinear hydrodynamic forces on two (or more)large vertical circular cylinders extending from the scabed to the water surface,subjected to nonlinear wave,is...An analytical method for the efficient investigation of the nonlinear hydrodynamic forces on two (or more)large vertical circular cylinders extending from the scabed to the water surface,subjected to nonlinear wave,is outlined.The variations of the nonlinear hydrodynamic forces with the frequency caused by waves and water depth are studied as well as the variations of the nonlinear interaction between cylinders agsinst the spacing of them. Compeisons are made with published resultS obtained by Masuda theoretically and experimentally, and gab agreement is shown.展开更多
Nonlinear diffraction of regular waves by an array of bottom-seated circular cylindersis investigated in frequency domain,based on a Stokes expansion approach.A complete semi-analyticalsolution is developed which allo...Nonlinear diffraction of regular waves by an array of bottom-seated circular cylindersis investigated in frequency domain,based on a Stokes expansion approach.A complete semi-analyticalsolution is developed which allows an efficient evaluation of the second-order potentials in the entirefluid domain,and the wave forces on the structure.Expressions are derived for the second-orderpotential in the vicinity of individual cylinders.These expressions have a simple form,thus providingan effective means for investigating the wave enhancement due to nonlinear interactions with multiplecylinders.Based on the present method,the wave run-up and free-surface elevations around an arrayof two,three and four cylinders are investigated numerically.展开更多
We make a comparison study of linear and nonlinear diffraction by a periodically poled lithium niobate[PPLN]dual linear-nonlinear thin-plate grating with weak surface corrugation against four types of white light sour...We make a comparison study of linear and nonlinear diffraction by a periodically poled lithium niobate[PPLN]dual linear-nonlinear thin-plate grating with weak surface corrugation against four types of white light sources.They are the ordinary halogen lamp thermal radiation source[WL1],the silica photonic crystal fiber supercontinuum nanosecond laser source[WL2],and two femtosecond white lasers made by a Ti:sapphire pump laser beam passing through a fused silica plate with significant spectrum broadening[WL3]and through a cascaded silica plate and a chirped PPLN crystal with ultrabroadband second-harmonic generation[WL4].The experiments show that the coherence,peak power,spectral bandwidth,profile,and flatness of the pump white light all contribute to shaping the characteristics of linear and nonlinear optical diffraction patterns.In particular,for WL1,WL2,and WL4,the peak power is not sufficiently large;thus,only linear diffraction occurs.For incoherent WL1,the interference is absent.Remarkably,when a femtosecond white laser with sufficiently large peak power[WL3]shines upon the PPLN grating,bright and sharp linear Bragg scattering spots,dispersive colored linear diffraction patterns,and nonlinear Cherenkov radiation nonlinear diffraction patterns are observed simultaneously by naked eyes.The experiments would enrich the basic physical and optical understanding of linear and nonlinear optical diffraction characteristics of ultrabroadband white laser sources.展开更多
Conventional nonlinear Raman–Nath diffraction(NRND)spots exhibit a straight-line distribution when the pump laser enters the nonlinear dielectric grating at normal incidence or at oblique incidence.Here,we report on ...Conventional nonlinear Raman–Nath diffraction(NRND)spots exhibit a straight-line distribution when the pump laser enters the nonlinear dielectric grating at normal incidence or at oblique incidence.Here,we report on the first observation of the conical NRND phenomenon from a submicron-thick periodically poled lithium niobate thin film(PPLNTF)sample under a near-infrared femtosecond pulse laser excitation at various cone angles.All the multi-order second harmonic generation(SHG)diffraction signals present a novel evolution arc-shaped arrangement feature.展开更多
The design of nonlinear photonic Vogel's spiral based on quasi-crystal theory was demonstrated.Two main parameters of Vogel's spiral were arranged to obtain multi-reciprocal circles.Typical structure was fabri...The design of nonlinear photonic Vogel's spiral based on quasi-crystal theory was demonstrated.Two main parameters of Vogel's spiral were arranged to obtain multi-reciprocal circles.Typical structure was fabricated by the near-infrared femtosecond laser poling technique,forming a nonlinear photonic structure,and multiple ring-like nonlinear Raman±Nath second-harmonic generation processes were realized and analyzed in detail.The structure for the cascaded thirdharmonic generation process was predicted.The results could help deepen the understanding of Vogel's spiral and quasi-crystal and pave the way for the combination of quasi-crystal theory with more aperiodic structures.展开更多
基金supported by the National Natural Science Foundation of China(Nos.62074127,U21A2073,62304173,62304175,62404177,61804122,11874142,61627812,61705176,11874102,11474048,and 61805068)the Natural Science Fund of Shaanxi Province(Nos.2018JQ6002,2021JQ062,2021JQ056,and 2021GY223)+3 种基金the Postdoctoral Science Foundation(Nos.2019M653637,2019M660256,and 2017M620300)the National Key Research and Development Program of China(Nos.2018YFE0125900,2021YFB3602100,2017YFB0402800,and 2017YFB0402802)the Fundamental Research Funds for the Central Universities(No.ZYGX2019J102)the Natural Science Basic Research Program of Shaanxi Province(No.2024JC-YBMS-505)。
文摘The emergence of hybrid nanostructures has paved a novel path for the development of nanotechnology and next-generation quantum devices.In this study,we report a remarkable enhancement of nonlinear diffraction achieved within a hybrid artificial molecule consisting of a semiconductor quantum dot(SQD)and a metal nanoparticle(MNP).Our findings reveal that the optical nonlinear properties of the hybrid system can be substantially enhanced due to the plasmon resonance of MNP.Specifically,reducing the interparticle distance and the SQD's size while increasing the MNP's size leads to a significant enhancement in the nonlinear phase modulation of the hybrid system.Meanwhile,the absorption spectra exhibit a redshift accompanied by linewidth broadening under the SQD-MNP coupling interaction controlled by geometric parameters,indicating plasmon-exciton energy transfer.On this basis,it is validated that the enhanced nonlinear phase modulation greatly improves the self-imaging visibility and the signal-to-noise ratio,and extends the near-field pattern over more Talbot lengths.We also demonstrate that the far-field diffraction efficiency is tunable via the coupling interaction between the artificial molecule and external fields,which is determined by the geometric structure,photon detuning,and Rabi frequency.For instance,the first-order diffraction efficiency can be increased from 39.58%to 55%if the geometric parameters of the hybrid system satisfy the threshold in non-resonance conditions.Such plasmon-enhanced optical lattices show potential for applications in all-optical modulators and all-optical switches operating at few-photon levels,and may also afford a novel perspective for the design and development of nanophotonics circuits and topological photonic devices.
基金Project supported by Science and Technology Project of Guangdong(Grant No.2020B010190001)the National Natural Science Foundation of China(Grant No.12434016)National Funded Postdoctoral Researcher Program(Grant No.GZB20240785)。
文摘When a laser beam is incident on a nonlinear grating with a laterally modulated second-order nonlinear coefficient,nonlinear diffraction of the noncollinear second-harmonic generation(SHG)signal occurs,with Raman–Nath nonlinear diffraction(NRND)being a prominent example.As these SHG NRND processes involve coupling between the fundamental-wave pump laser vectorial field and the SHG laser vectorial field through the second-order nonlinearity secondrank tensor of the nonlinear crystal,the nonlinear interaction between light and the nonlinear grating can be manipulated by adjusting the polarization state of the pump laser.In this paper,we derive the relationship between the polarization state of the incident light and the generated nonlinear diffraction signal based on the nonlinear coupled wave equation and experimentally validate the predicted diffraction characteristics.The results show that the optical properties of each order of NRND are highly sensitive to the polarization angle of the incident pump laser beam.
基金supported by the Science and Technology Project of Guangdong Province,China(Grant No.2020B010190001)the National Natural Science Foundation of China(Grant No.12434016)the National Funded Postdoctoral Researcher Program(Grant No.GZB20240785).
文摘When a pump laser beam strikes the surface of a nonlinear crystal with modulated second-order nonlinearity,various nonlinear diffraction phenomena occur,with nonlinear Raman–Nath diffraction(NRND)being a prominent example.In this study,we use an 800-nm Ti:sapphire femtosecond laser beam to pump the surface of a periodically poled lithium niobate(PPLN)crystal thin-plate nonlinear grating.By rotating the crystal,we change the incidence angle and observe and measure the exit angle,polarization,and power of NRND spots on the other side of the crystal.The experiment shows that NRND characteristics are highly sensitive to the incidence angle of the pump laser beam,which are consistent with the theoretical prediction.We expect that this research will advance the understanding of nonlinear diffraction and provide valuable insights for nonlinear optical interaction in complicated geometric and physical configurations.
文摘We present in this paper a semi-analytical solution for second-order wave diffraction by a vertical circular cylinder in bichromatic waves. On the base of the usual assumption of an irrotational flow, the wave-diffraction problems at second-order sum-frequency and difference-frequency are considered. The corresponding second-order diffraction potentials are decomposed into three parts, these are associated with the second-order incident wave, the quadratic forcing terras on the free-surface due to the first-order potential, and the linearised free-wave component resulting from the boundary condition on the body surface. A particular solution which exactly satisfies the inhomogeneous free-surface condition has been derived. Numerical results for the quadratic transfer functions of the second-order force components are given, and are compared with those obtained using numerical solutions (Kim & Yue, 1990,Moubayed & Williams 1995). These quadratic functions are useful in calculating the exciting forces on a circular cylinder of large dimension, fixed in irregular wave fields.
文摘An analytical method for the efficient investigation of the nonlinear hydrodynamic forces on two (or more)large vertical circular cylinders extending from the scabed to the water surface,subjected to nonlinear wave,is outlined.The variations of the nonlinear hydrodynamic forces with the frequency caused by waves and water depth are studied as well as the variations of the nonlinear interaction between cylinders agsinst the spacing of them. Compeisons are made with published resultS obtained by Masuda theoretically and experimentally, and gab agreement is shown.
文摘Nonlinear diffraction of regular waves by an array of bottom-seated circular cylindersis investigated in frequency domain,based on a Stokes expansion approach.A complete semi-analyticalsolution is developed which allows an efficient evaluation of the second-order potentials in the entirefluid domain,and the wave forces on the structure.Expressions are derived for the second-orderpotential in the vicinity of individual cylinders.These expressions have a simple form,thus providingan effective means for investigating the wave enhancement due to nonlinear interactions with multiplecylinders.Based on the present method,the wave run-up and free-surface elevations around an arrayof two,three and four cylinders are investigated numerically.
基金supported by the National Natural Science Foundation of China(No.12434016)the Science and Technology Project of Guangdong(No.2020B010190001)the National Funded Postdoctoral Researcher Program(No.GZB20240785)。
文摘We make a comparison study of linear and nonlinear diffraction by a periodically poled lithium niobate[PPLN]dual linear-nonlinear thin-plate grating with weak surface corrugation against four types of white light sources.They are the ordinary halogen lamp thermal radiation source[WL1],the silica photonic crystal fiber supercontinuum nanosecond laser source[WL2],and two femtosecond white lasers made by a Ti:sapphire pump laser beam passing through a fused silica plate with significant spectrum broadening[WL3]and through a cascaded silica plate and a chirped PPLN crystal with ultrabroadband second-harmonic generation[WL4].The experiments show that the coherence,peak power,spectral bandwidth,profile,and flatness of the pump white light all contribute to shaping the characteristics of linear and nonlinear optical diffraction patterns.In particular,for WL1,WL2,and WL4,the peak power is not sufficiently large;thus,only linear diffraction occurs.For incoherent WL1,the interference is absent.Remarkably,when a femtosecond white laser with sufficiently large peak power[WL3]shines upon the PPLN grating,bright and sharp linear Bragg scattering spots,dispersive colored linear diffraction patterns,and nonlinear Cherenkov radiation nonlinear diffraction patterns are observed simultaneously by naked eyes.The experiments would enrich the basic physical and optical understanding of linear and nonlinear optical diffraction characteristics of ultrabroadband white laser sources.
基金Science and Technology Project of Guangdong(2020B010190001)National Natural Science Foundation of China(12434016,11974119)+1 种基金Guangzhou Science and Technology Plan Project(2023A04J1309)National Funded Postdoctoral Researcher Program(GZB20240785)。
文摘Conventional nonlinear Raman–Nath diffraction(NRND)spots exhibit a straight-line distribution when the pump laser enters the nonlinear dielectric grating at normal incidence or at oblique incidence.Here,we report on the first observation of the conical NRND phenomenon from a submicron-thick periodically poled lithium niobate thin film(PPLNTF)sample under a near-infrared femtosecond pulse laser excitation at various cone angles.All the multi-order second harmonic generation(SHG)diffraction signals present a novel evolution arc-shaped arrangement feature.
基金supported by the National Natural Science Foundation of China(Nos.62275136,61905124,12274248,and 62090063)the Natural Science Foundation of Zhejiang Province(No.LY22F050009)+1 种基金the Yongjiang Scholar Foundation of Ningbothe K.C.Wong Magna Fund of Ningbo University。
文摘The design of nonlinear photonic Vogel's spiral based on quasi-crystal theory was demonstrated.Two main parameters of Vogel's spiral were arranged to obtain multi-reciprocal circles.Typical structure was fabricated by the near-infrared femtosecond laser poling technique,forming a nonlinear photonic structure,and multiple ring-like nonlinear Raman±Nath second-harmonic generation processes were realized and analyzed in detail.The structure for the cascaded thirdharmonic generation process was predicted.The results could help deepen the understanding of Vogel's spiral and quasi-crystal and pave the way for the combination of quasi-crystal theory with more aperiodic structures.
