In an open-circuit dissipative photovoltaic （PV） crystal, by considering the diffusion effect, the deflection of bright dissipative photovoltaic （DPV） solitons has been investigated by employing numerical techniqu...In an open-circuit dissipative photovoltaic （PV） crystal, by considering the diffusion effect, the deflection of bright dissipative photovoltaic （DPV） solitons has been investigated by employing numerical technique and perturbational procedure. The relevant results show that the centre of the optical beam moves along a parabolic trajectory, while the central spatial-frequency component shifts linearly with the propagation distance; furthermore, both the spatial deflection and the angular derivation are associated with the photovoltaic field. Such DPV solitons have a fixed deflection degree completely determined by the parameters of the dissipative system. The small bending cannot affect the formation of the DPV soliton via two-wave mixing.展开更多
The dynamical evolution of both signal and pump beams are traced by numerically solving the coupled-wave equation for a photorefractive two-wave mixing system. The direct simulations show that, when the intensity rati...The dynamical evolution of both signal and pump beams are traced by numerically solving the coupled-wave equation for a photorefractive two-wave mixing system. The direct simulations show that, when the intensity ratio of the pump beam to the signal beam is large enough, the pump beam presents a common decaying behaviour without modulational instability （MI）, while the signal beam can evolve into a quasistable spatial soliton within a regime in which the pump beam is depleted slightly. The larger the ratio is, the longer the regime is. Such quasistable solitons can overcome the initial perturbations and numerical noises in the course of propagation, perform several cycles of slow oscillation in intensity and width, and persist over tens of diffraction lengths. From physical viewpoints, these solitons actually exist as completely rigorous physical objects. If the ratio is quite small, the pump beam is apt to show MI, during which the signal beam experiences strong expansion and shrinking in width and a drastic oscillation in intensity, or completely breaks up. The simulations using actual experimental parameters demonstrate that the observation of an effectively stable soliton is quite possible in the proposed system.展开更多
In a biased photorefractive crystal, the process of two one-dimensional waves mixing, i.e., the dynamical evolution of both pump beam and signal beam, is traced by numerically solving the coupled-wave equation. Direct...In a biased photorefractive crystal, the process of two one-dimensional waves mixing, i.e., the dynamical evolution of both pump beam and signal beam, is traced by numerically solving the coupled-wave equation. Direct simulations show that the propagation and stability of the two beams are completely determined by the system parameters, such as the external bias field, the intensity and the beam waist of the pump beam. By adjusting these parameters, one can control the state of two Gaussian waves mixing. The numerical results are helpful for performing a two-wave mixing experiment.展开更多
The dynamical evolution and stability of bright dissipative holographic solitons in biased photorefractive materials in which the self-trapping beam obtains a gain from the pump beam via two-wave mixing has been inves...The dynamical evolution and stability of bright dissipative holographic solitons in biased photorefractive materials in which the self-trapping beam obtains a gain from the pump beam via two-wave mixing has been investigated numerically. Results show that these solitons are stable relative to small perturbations. Adjusting some system parameters, such as the bias field and the angle between beams, can easily control the generation of such solitons. Potential applications in optical switches or repeaters are discussed.展开更多
In this paper, a nonlocal two-wave interaction system from the Manakov hierarchy is investigated via the Riemann–Hilbert approach. Based on the spectral analysis of the Lax pair, a Riemann–Hilbert problem for the no...In this paper, a nonlocal two-wave interaction system from the Manakov hierarchy is investigated via the Riemann–Hilbert approach. Based on the spectral analysis of the Lax pair, a Riemann–Hilbert problem for the nonlocal two-wave interaction system is constructed. By discussing the solutions of this Riemann–Hilbert problem in both the regular and nonregular cases, we explicitly present the N-soliton solution formula of the nonlocal two-wave interaction system. Moreover,the dynamical behaviour of the single-soliton solution is shown graphically.展开更多
The intensity and phase formulas that are valid for the saturation and intermediate regime (before saturation) are derived, and the analytical expressions with the ratio of saturation intensity to total incident inten...The intensity and phase formulas that are valid for the saturation and intermediate regime (before saturation) are derived, and the analytical expressions with the ratio of saturation intensity to total incident intensity as their explicit variable are obtained. The intensity dependence of stationary energy transfer in photorefractive codirectional two-wave mixing is examined. It is necessary to using these formulas in some problems, such as the temperature or intensity dependence of two-wave mixing. A method of measuring exponential gain coefficient is presented, which is suitable for two-wave mixing in intermediate regime.展开更多
The new method of measuring the ratio of thermal emission rate to the photoexcitation constant is presented. The temperature dependence of the ratio for Cr:GaAs is calculated by using the previously published data of ...The new method of measuring the ratio of thermal emission rate to the photoexcitation constant is presented. The temperature dependence of the ratio for Cr:GaAs is calculated by using the previously published data of two-wave mixing. Results show that the calculating data and previous phenomenological theoretic ones coincide with each other very well.展开更多
In this paper, the influence of temperature on the intracavity optical parametric oscillator（IOPO） is investigated by using the stimulated temperature-dependent emission cross section of laser crystal. The rate equa...In this paper, the influence of temperature on the intracavity optical parametric oscillator（IOPO） is investigated by using the stimulated temperature-dependent emission cross section of laser crystal. The rate equations under plane wave approximation have been used for simulation of signal output pulse. Results show that the signal output pulse width is decreased by increasing the laser crystal temperature. Also, the signal output energy is increased by the increasing of the laser crystal temperature. The simulation results for IOPO based on Nd：YAG and Nd：YVO_4, show that the signal pulse energies are increased by 3.2 and 5.6 times respectively when the laser crystal temperature increased from 15℃ to 300℃. The presented model indicates that the temperature sensitivity of Nd：YVO_4-based IOPOs is more than that of Nd：YAG-based IOPOs which is expected from a physical point of view.展开更多
The current study employs the novel Hirota bilinear scheme to investigate the nonlinear model.Thus,we acquire some two-wave and breather wave solutions to the governing equation.Breathers are pulsating localized struc...The current study employs the novel Hirota bilinear scheme to investigate the nonlinear model.Thus,we acquire some two-wave and breather wave solutions to the governing equation.Breathers are pulsating localized structures that have been used to mimic extreme waves in a variety of nonlinear dispersive media with a narrow banded starting process.Several recent investigations,on the other hand,imply that breathers can survive in more complex habitats,such as random seas,despite the attributed physical restrictions.The authenticity and genuineness of all the acquired solutions agreed with the original equation.In order to shed more light on these novel solutions,we plot the 3-dimensional and contour graphs to the reported solutions with some suitable values.The governing model is also stable because of the idea of linear stability.The study’s findings may help explain the physics behind some of the challenges facing ocean engineers.展开更多
Single crystals subjected to shock compression exhibit responses with distinct two-wave structures for certain crystal orientations.However,little is known to date regarding how the shock response depends on crystal o...Single crystals subjected to shock compression exhibit responses with distinct two-wave structures for certain crystal orientations.However,little is known to date regarding how the shock response depends on crystal orientation,and especially why the two-wave structure depends on the crystal orientation.In this work,molecular dynamics simulations of shock compressions in copper single crystals are performed to investigate the orientation dependence of shock responses and the corresponding deformation mechanisms.Four copper single crystals with[001],[011],[012],and[123]crystal orientations along the depth direction are investigated.The[011],[012],and[123]crystal orientations of copper single crystals show distinct two-wave structures in their shock responses,while such a two-wave structure in the shock response is not seen for those orientations having a[001]crystal orientation.The potential causes are analyzed by considering the propagation velocities of both elastic and plastic waves.We develop a technique for identifying twin structures in face-centered cubic crystals and this technique can effectively identify the twin structure.The morphology of shock-induced defects(e.g.,dislocations and twins)shows the significant dependence of crystal orientation and the mechanisms behind these are discussed in detail.Finally,the Johnson-Cook constitutive model describing dynamic deformations at high temperatures and high strain rates is used to analyze the relationships between the shock responses and microscopic defects.The predictions of the Johnson-Cook constitutive model are consistent with the results of the molecular dynamics simulations.展开更多
The transverse effects of two Gauss waves mixing in a photovoltaic photorefractive crystal,i.e.,the dynamical evolutions of signal beam with different parameters,are traced numerically and experimentally.Both the one-...The transverse effects of two Gauss waves mixing in a photovoltaic photorefractive crystal,i.e.,the dynamical evolutions of signal beam with different parameters,are traced numerically and experimentally.Both the one-dimensional numerical simulations and two-dimensional experimental investigations show that the self-focusing effect of signal beam becomes more obvious as the intensity of pump beam and the angle between the signal and pump beams increase.In accordance with these results,the state of two Gaussian waves mixing is controllable.展开更多
When the magnitude of sub-scale ographic forcing is comparable with explicitly ordinary dynamic forcing, the drag effect reduced by ographic gravity wave is to be significant for maintaining dynamic balance of atmosph...When the magnitude of sub-scale ographic forcing is comparable with explicitly ordinary dynamic forcing, the drag effect reduced by ographic gravity wave is to be significant for maintaining dynamic balance of atmospheric circulation, as well as the momentum and energy transport. Such sub-scale ographic forcing should be introduced into numerically atmospheric model by means of drag being parameterized. Furthermore, the currently mature ographic gravity wave drag （OGWD） parameterization, i.e., the so-called first-generation （based on lineal single-wave theoretical framework） or the second-generation drag parameterization （including an important extra forcing by the contribution of critical level absorption）, cannot correctly and effectly describe the vertical profile of wave stress under the influence of ambient wind shearing. Based on aforementioned consideration, a new two-wave scheme was proposed to parameterize the ographic gravity wave drag by means of freely propagating gravity waves. It starts with a second order WKB approximation, and treats the wave stress attenuations caused by either the selective critical level absorption or the classical critical level absorption explicitly; while in the regions where critical levels are absent, it transports the wave stress vertically by two sinusoidal waves and deposits them and then damps them according to the wave saturation criteria. This scheme is thus used to conduct some sample computations over the Dabie Mountain region of East China, as an example. The results showed that the new two-wave scheme is able to model the vertical distribution of the wave stress more realistically.展开更多
In this paper,new explicit unidirectional wave solutions for the modified-mixed KdV equation and bidi-rectional waves for the Benjamin Ono equation are studied.New extension of the rational sine-cosine and sinh-cosh m...In this paper,new explicit unidirectional wave solutions for the modified-mixed KdV equation and bidi-rectional waves for the Benjamin Ono equation are studied.New extension of the rational sine-cosine and sinh-cosh methods are used.In addition,an extension of the recent polynomial function method is applied as well.Different types of topological and non-topological soliton solutions are extracted to the proposed models and categorized by providing 2D and 3D graphs.Finally,some physical properties of the new bidirectional waves solutions to the Benjamin Ono model are discussed.展开更多
In recent periods, some organic conjugated polymers with large nonlinear optical effectand fast responses are being studied widely. With them, people hope to produce ultrafastoptronic devices, such as optical switches...In recent periods, some organic conjugated polymers with large nonlinear optical effectand fast responses are being studied widely. With them, people hope to produce ultrafastoptronic devices, such as optical switches or optical modulators. However, up to now, fewpolymeric samples have been discovered to have enough large nonlinear optical effect orfast time responses to satisfy the practical applications. In this note, we report展开更多
45°-cut BaTiO<sub>3</sub> crystals have been studied and used for their enhanced photorefractive performance. Theoretically, BaTiO<sub>3</sub> crystal has its maximum two-wave mixing （TWM...45°-cut BaTiO<sub>3</sub> crystals have been studied and used for their enhanced photorefractive performance. Theoretically, BaTiO<sub>3</sub> crystal has its maximum two-wave mixing （TWM） gain when the grating wave vector K<sub>g</sub> is about 45° tilted with respect to its C-axis. However, for thick samples, the effective gain is usually reduced because of the fanning problem. At steady states, the effective TWM gain of a 45°-cut BaTiO<sub>3</sub> is normally展开更多
基金Project supported by the National Natural Science Foundation of China （Grant Nos 10574051 and 10174025）.
文摘In an open-circuit dissipative photovoltaic （PV） crystal, by considering the diffusion effect, the deflection of bright dissipative photovoltaic （DPV） solitons has been investigated by employing numerical technique and perturbational procedure. The relevant results show that the centre of the optical beam moves along a parabolic trajectory, while the central spatial-frequency component shifts linearly with the propagation distance; furthermore, both the spatial deflection and the angular derivation are associated with the photovoltaic field. Such DPV solitons have a fixed deflection degree completely determined by the parameters of the dissipative system. The small bending cannot affect the formation of the DPV soliton via two-wave mixing.
基金Project supported by the National Natural Science Foundation of China （Grant Nos 10574051 and 10174025）.
文摘The dynamical evolution of both signal and pump beams are traced by numerically solving the coupled-wave equation for a photorefractive two-wave mixing system. The direct simulations show that, when the intensity ratio of the pump beam to the signal beam is large enough, the pump beam presents a common decaying behaviour without modulational instability （MI）, while the signal beam can evolve into a quasistable spatial soliton within a regime in which the pump beam is depleted slightly. The larger the ratio is, the longer the regime is. Such quasistable solitons can overcome the initial perturbations and numerical noises in the course of propagation, perform several cycles of slow oscillation in intensity and width, and persist over tens of diffraction lengths. From physical viewpoints, these solitons actually exist as completely rigorous physical objects. If the ratio is quite small, the pump beam is apt to show MI, during which the signal beam experiences strong expansion and shrinking in width and a drastic oscillation in intensity, or completely breaks up. The simulations using actual experimental parameters demonstrate that the observation of an effectively stable soliton is quite possible in the proposed system.
基金supported by the National Natural Science Foundations of China(Grant Nos 10174025 and 10574051)
文摘In a biased photorefractive crystal, the process of two one-dimensional waves mixing, i.e., the dynamical evolution of both pump beam and signal beam, is traced by numerically solving the coupled-wave equation. Direct simulations show that the propagation and stability of the two beams are completely determined by the system parameters, such as the external bias field, the intensity and the beam waist of the pump beam. By adjusting these parameters, one can control the state of two Gaussian waves mixing. The numerical results are helpful for performing a two-wave mixing experiment.
基金Project supported by the National Natural Science Foundation of China （Grant No 10574051）.
文摘The dynamical evolution and stability of bright dissipative holographic solitons in biased photorefractive materials in which the self-trapping beam obtains a gain from the pump beam via two-wave mixing has been investigated numerically. Results show that these solitons are stable relative to small perturbations. Adjusting some system parameters, such as the bias field and the angle between beams, can easily control the generation of such solitons. Potential applications in optical switches or repeaters are discussed.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11331008 and 11522112)
文摘In this paper, a nonlocal two-wave interaction system from the Manakov hierarchy is investigated via the Riemann–Hilbert approach. Based on the spectral analysis of the Lax pair, a Riemann–Hilbert problem for the nonlocal two-wave interaction system is constructed. By discussing the solutions of this Riemann–Hilbert problem in both the regular and nonregular cases, we explicitly present the N-soliton solution formula of the nonlocal two-wave interaction system. Moreover,the dynamical behaviour of the single-soliton solution is shown graphically.
文摘The intensity and phase formulas that are valid for the saturation and intermediate regime (before saturation) are derived, and the analytical expressions with the ratio of saturation intensity to total incident intensity as their explicit variable are obtained. The intensity dependence of stationary energy transfer in photorefractive codirectional two-wave mixing is examined. It is necessary to using these formulas in some problems, such as the temperature or intensity dependence of two-wave mixing. A method of measuring exponential gain coefficient is presented, which is suitable for two-wave mixing in intermediate regime.
文摘The new method of measuring the ratio of thermal emission rate to the photoexcitation constant is presented. The temperature dependence of the ratio for Cr:GaAs is calculated by using the previously published data of two-wave mixing. Results show that the calculating data and previous phenomenological theoretic ones coincide with each other very well.
文摘In this paper, the influence of temperature on the intracavity optical parametric oscillator（IOPO） is investigated by using the stimulated temperature-dependent emission cross section of laser crystal. The rate equations under plane wave approximation have been used for simulation of signal output pulse. Results show that the signal output pulse width is decreased by increasing the laser crystal temperature. Also, the signal output energy is increased by the increasing of the laser crystal temperature. The simulation results for IOPO based on Nd：YAG and Nd：YVO_4, show that the signal pulse energies are increased by 3.2 and 5.6 times respectively when the laser crystal temperature increased from 15℃ to 300℃. The presented model indicates that the temperature sensitivity of Nd：YVO_4-based IOPOs is more than that of Nd：YAG-based IOPOs which is expected from a physical point of view.
文摘The current study employs the novel Hirota bilinear scheme to investigate the nonlinear model.Thus,we acquire some two-wave and breather wave solutions to the governing equation.Breathers are pulsating localized structures that have been used to mimic extreme waves in a variety of nonlinear dispersive media with a narrow banded starting process.Several recent investigations,on the other hand,imply that breathers can survive in more complex habitats,such as random seas,despite the attributed physical restrictions.The authenticity and genuineness of all the acquired solutions agreed with the original equation.In order to shed more light on these novel solutions,we plot the 3-dimensional and contour graphs to the reported solutions with some suitable values.The governing model is also stable because of the idea of linear stability.The study’s findings may help explain the physics behind some of the challenges facing ocean engineers.
基金supported by the National Natural Science Foundation of China(Grant Nos.11972165,and 11502085)the Japan Society for the Promotion of Science(Grant No.P18067)the Fundamental Research Funds for the Central Universities of China(Grant No.2016YXMS097)。
文摘Single crystals subjected to shock compression exhibit responses with distinct two-wave structures for certain crystal orientations.However,little is known to date regarding how the shock response depends on crystal orientation,and especially why the two-wave structure depends on the crystal orientation.In this work,molecular dynamics simulations of shock compressions in copper single crystals are performed to investigate the orientation dependence of shock responses and the corresponding deformation mechanisms.Four copper single crystals with[001],[011],[012],and[123]crystal orientations along the depth direction are investigated.The[011],[012],and[123]crystal orientations of copper single crystals show distinct two-wave structures in their shock responses,while such a two-wave structure in the shock response is not seen for those orientations having a[001]crystal orientation.The potential causes are analyzed by considering the propagation velocities of both elastic and plastic waves.We develop a technique for identifying twin structures in face-centered cubic crystals and this technique can effectively identify the twin structure.The morphology of shock-induced defects(e.g.,dislocations and twins)shows the significant dependence of crystal orientation and the mechanisms behind these are discussed in detail.Finally,the Johnson-Cook constitutive model describing dynamic deformations at high temperatures and high strain rates is used to analyze the relationships between the shock responses and microscopic defects.The predictions of the Johnson-Cook constitutive model are consistent with the results of the molecular dynamics simulations.
基金supported by the National Natural Science Foundation of China (Grant Nos. 10174025 and 10574051)
文摘The transverse effects of two Gauss waves mixing in a photovoltaic photorefractive crystal,i.e.,the dynamical evolutions of signal beam with different parameters,are traced numerically and experimentally.Both the one-dimensional numerical simulations and two-dimensional experimental investigations show that the self-focusing effect of signal beam becomes more obvious as the intensity of pump beam and the angle between the signal and pump beams increase.In accordance with these results,the state of two Gaussian waves mixing is controllable.
基金the State Natural Science Foundation of China under Grant Nos.40775034,40575017,and 90715031the Natural Science Foundation of Jiangsu under Grant No.BK99020the open project of State Key Laboratory of Severe Weather,Chinese Academy of Meteorological Sciences.
文摘When the magnitude of sub-scale ographic forcing is comparable with explicitly ordinary dynamic forcing, the drag effect reduced by ographic gravity wave is to be significant for maintaining dynamic balance of atmospheric circulation, as well as the momentum and energy transport. Such sub-scale ographic forcing should be introduced into numerically atmospheric model by means of drag being parameterized. Furthermore, the currently mature ographic gravity wave drag （OGWD） parameterization, i.e., the so-called first-generation （based on lineal single-wave theoretical framework） or the second-generation drag parameterization （including an important extra forcing by the contribution of critical level absorption）, cannot correctly and effectly describe the vertical profile of wave stress under the influence of ambient wind shearing. Based on aforementioned consideration, a new two-wave scheme was proposed to parameterize the ographic gravity wave drag by means of freely propagating gravity waves. It starts with a second order WKB approximation, and treats the wave stress attenuations caused by either the selective critical level absorption or the classical critical level absorption explicitly; while in the regions where critical levels are absent, it transports the wave stress vertically by two sinusoidal waves and deposits them and then damps them according to the wave saturation criteria. This scheme is thus used to conduct some sample computations over the Dabie Mountain region of East China, as an example. The results showed that the new two-wave scheme is able to model the vertical distribution of the wave stress more realistically.
文摘In this paper,new explicit unidirectional wave solutions for the modified-mixed KdV equation and bidi-rectional waves for the Benjamin Ono equation are studied.New extension of the rational sine-cosine and sinh-cosh methods are used.In addition,an extension of the recent polynomial function method is applied as well.Different types of topological and non-topological soliton solutions are extracted to the proposed models and categorized by providing 2D and 3D graphs.Finally,some physical properties of the new bidirectional waves solutions to the Benjamin Ono model are discussed.
文摘In recent periods, some organic conjugated polymers with large nonlinear optical effectand fast responses are being studied widely. With them, people hope to produce ultrafastoptronic devices, such as optical switches or optical modulators. However, up to now, fewpolymeric samples have been discovered to have enough large nonlinear optical effect orfast time responses to satisfy the practical applications. In this note, we report
基金Project supported by the K.C.Wong Education Foundation. Hong Kong
文摘45°-cut BaTiO<sub>3</sub> crystals have been studied and used for their enhanced photorefractive performance. Theoretically, BaTiO<sub>3</sub> crystal has its maximum two-wave mixing （TWM） gain when the grating wave vector K<sub>g</sub> is about 45° tilted with respect to its C-axis. However, for thick samples, the effective gain is usually reduced because of the fanning problem. At steady states, the effective TWM gain of a 45°-cut BaTiO<sub>3</sub> is normally
