Liquid crystal spatial light modulator （LCSLM） realizing equal-intensity multiple beams often has some features, i.e., phase valley between two adjacent pixels, flybaek region when phase decreases immediately from 2...Liquid crystal spatial light modulator （LCSLM） realizing equal-intensity multiple beams often has some features, i.e., phase valley between two adjacent pixels, flybaek region when phase decreases immediately from 2~r to 0, and inevitable backplane curvature, which are different from those of most conventional diffractive optical elements （DOEs）, such as static DOEs. For optimal intensity uniformity, equal-intensity multi-beam generation must be considered for these artifacts. We present a tunable-grating method in which the intensity uniformity can be improved by considering the LCSLM artifacts. For instance, tuning phase modulation depth of the grating, called isosceles triangle multilevel phase grating （ITMPG）, can be used not only to improve the intensity uniformity, but also to fast steer four beams with narrow beamwidths, determined by the same effective aperture of ITMPG. Improved intensity uniformity and high relative diffraction efficiency are demonstrated through experiments with phase-only LCSLM.展开更多
We investigate the co-propagation of a strong pump beam and a weak signal beam in lead glass, and find that the large phase shift of the strongly nonlocal spatial optical soliton （SNSOS） can be realized via cross-ph...We investigate the co-propagation of a strong pump beam and a weak signal beam in lead glass, and find that the large phase shift of the strongly nonlocal spatial optical soliton （SNSOS） can be realized via cross-phase modulation. The theoretical study suggests a synchronous propagation of the pump SNSOS and the signal SNSOS under the required initial condition. A π-phase shift of the signal SNSOS is experimentally obtained by changing the power of the pump SNSOS by about 13 mW around the soliton critical power, which agrees qualitatively with our theoretical prediction. The ratio of the phase shift rate of the signal SNSOS to that of the pump SNSOS shows a close match to the reciprocal of the ratio between their wavelengths.展开更多
Using a space filled with black-body radiation, we derive a generalization for the Clausius-Clapeyron relation to account for a phase transition, which in-volves a change in spatial dimension. We consider phase transi...Using a space filled with black-body radiation, we derive a generalization for the Clausius-Clapeyron relation to account for a phase transition, which in-volves a change in spatial dimension. We consider phase transitions from dimension of space, n, to dimension of space, (n - 1), and vice versa, from (n - 1) to n -dimensional space. For the former we can calculate a specific release of latent heat, a decrease in entropy, and a change in volume. For the latter, we derive an expression for the absorption of heat, the increase in entropy, and the difference in volume. Total energy is conserved in this transformation process. We apply this model to black-body radiation in the early universe and find that for a transition from n = 4 to (n - 1) = 3, there is an immense decrease in entropy accompanied by a tremendous change in volume, much like condensation. However, unlike condensation, the volume change is not three-dimensional. The volume changes from V4, a four-dimensional construct, to V3, a three-dimensional entity, which can be considered a subspace of V4. As a specific example of how the equation works, we consider a transition temperature of 3 × 1027 Kelvin, and assume, furthermore, that the latent heat release in three-dimensional space is 1.8 × 1094 Joules. We find that for this transition, the internal energy densities, the entropy densities, and the volumes assume the following values (photons only). In four-dimensional space, we obtain, u4 = 1.15×10125 J? m-4, s4 = 4.81×1097 J? m-4? K-1, and V4 = 2.14×10-31 m4. In three-dimensional space, we have u3 = 6.13×1094 J? m-3, s3 = 2.72×1067 J? m-3? K-1, and V3 = 0.267 m3. The subscripts 3 and 4 refer to three-dimensional and four-dimensional quantities, respectively. We speculate, based on the tremendous change in volume, the explosive release of latent heat, and the magnitudes of the other quantities calculated, that this type of transition might have a connection to inflation. With this work, we prove that space, in and of itself, has an inherent energy content. This is so because giving up space releases latent heat, and buying space costs latent heat, which we can quantify. This is in addition to the energy contained within that space due to radiation. We can determine the specific amount of heat exchanged in transitioning between different spatial dimensions with our generalized Clausius-Clapeyron equation.展开更多
The spatial distribution in high-order harmonic generation（HHG） from the asymmetric diatomic molecule He H^（2＋） is investigated by numerically solving the non-Born–Oppenheimer time-dependent Schr？dinger equatio...The spatial distribution in high-order harmonic generation（HHG） from the asymmetric diatomic molecule He H^（2＋） is investigated by numerically solving the non-Born–Oppenheimer time-dependent Schr？dinger equation（TDSE）. The spatial distribution of the HHG spectra shows that there is little contribution in HHG around the geometric center of two nuclei（z = 1.17 a.u.） and the equilibrium internuclear position of the H nucleus（z = 3.11 a.u.）. We demonstrate the carrier envelope phase（CEP） effect on the spatial distribution of HHG in a few-cycle laser pulse. The HHG process is investigated by the time evolution of the electronic density distribution. The time–frequency analysis of HHG from two nuclei in HeH^（2＋） is presented to further explain the underlying physical mechanism.展开更多
Molecular dynamics simulations are performed to investigate the liquid-liquid phase transition （LLPT） and the spatial heterogeneity in A1-Pb monotectic alloys. The results reveal that homogeneous liquid AI-Pb alloy ...Molecular dynamics simulations are performed to investigate the liquid-liquid phase transition （LLPT） and the spatial heterogeneity in A1-Pb monotectic alloys. The results reveal that homogeneous liquid AI-Pb alloy undergoes an LLPT, separating into Al-rich and Pb-rich domains, which is quite different from the isocompositional liquid water with a transition between low-density liquid （LDL） and high-density liquid （HDL）. With spatial heterogeneity becoming large, LLPT takes place correspondingly. The relationship between the cooling rate, relaxation temperature and percentage of A1 and the spatial heterogeneity is also reported. This study may throw light on the relationship between the structure heterogeneity and LLPT, which provides novel strategies to control the microstructures in the fabrication of the material with high performance.展开更多
By using the generalized Debye diffraction integral, this paper studies the spatial correlation properties and phase singularity annihilation of apertured Gaussian Schell-model （GSM） beams in the focal region. It is...By using the generalized Debye diffraction integral, this paper studies the spatial correlation properties and phase singularity annihilation of apertured Gaussian Schell-model （GSM） beams in the focal region. It is shown that the width of the spectral degree of coherence can be larger, less than or equal to the corresponding width of spectral density, which depends not only on the scalar coherence length of the beams, but also on the truncation parameter. With a gradual increase of the truncation parameter, a pair of phase singularities of the spectral degree of coherence in the focal plane approaches each other, resulting in subwavelength structures. Finally, the annihilation of pairs of phase singularities takes place at a certain value of the truncation parameter. With increasing scalar coherence length, the annihilation occurs at the larger truncation parameter. However, the creation process of phase singularities outside the focal plane is not found for GSM beams.展开更多
Various pattern evolutions are presented in one- and two-dimensional spatially coupled phase-conjugate systems （SCPCSs）. As the system parameters change, different patterns are obtained from the period-doubling of k...Various pattern evolutions are presented in one- and two-dimensional spatially coupled phase-conjugate systems （SCPCSs）. As the system parameters change, different patterns are obtained from the period-doubling of kink-antikinks in space to the spatiotemporal chaos in a one-dimensional SCPCS. The homogeneous symmetric states induce symmetry breaking from the four corners and the boundaries, finally leading to spatiotemporal chaos with the increase of the iteration time in a two-dimensional SCPCS. Numerical simulations are very helpful for understanding the complex optical phenomena.展开更多
This paper obtains the exact analytical solution of atomic Raman-Nath diffraction in the coordinate representation and discusses the influence of different initial conditions and detunings on the atomic spatial popula...This paper obtains the exact analytical solution of atomic Raman-Nath diffraction in the coordinate representation and discusses the influence of different initial conditions and detunings on the atomic spatial population distribution. The phase difference between the dipole matrix element and initial atomic population may influence the atomic spatial population distribution after diffraction, which has never been discussed before as far as we know. It offers a method to measure the phase by the spatial population distribution, which is interesting in the study of quantum optics.展开更多
We study the possible topological phase in a one-dimensional（1D） quantum wire with an oscillating Rashba spin–orbital coupling in real space. It is shown that there are a pair of particle–hole symmetric gaps formi...We study the possible topological phase in a one-dimensional（1D） quantum wire with an oscillating Rashba spin–orbital coupling in real space. It is shown that there are a pair of particle–hole symmetric gaps forming in the bulk energy band and fractional boundary states residing in the gap when the system has an inversion symmetry. These states are topologically nontrivial and can be characterized by a quantized Berry phase ±π or nonzero Chern number through dimensional extension. When the Rashba spin–orbital coupling varies slowly with time, the system can pump out 2 charges in a pumping cycle because of the spin flip effect. This quantized pumping is protected by topology and is robust against moderate disorders as long as the disorder strength does not exceed the opened energy gap.展开更多
The first-principles calculations based on density functional theory combined with cluster expansion techniques and Monte Carlo （MC） simulations were used to study the phase diagrams of both wurtzite （WZ） and zinc...The first-principles calculations based on density functional theory combined with cluster expansion techniques and Monte Carlo （MC） simulations were used to study the phase diagrams of both wurtzite （WZ） and zinc-blende （ZB） Cdl_xZnxS alloys. All formation energies are positive for WZ and ZB Cdl-xZnxS alloys, which means that the Cdl-xZnxS alloys are unstable and have a tendency to phase separation. For WZ and ZB Cdl_xZnxS alloys, the consolute temperatures are 655 K and 604 K, respectively, and they both have an asymmetric miscibility gap. We obtained the spatial distributions of Cd and Zn atoms in WZ and ZB Cd0.sZn0.sS alloys at different temperatures by MC simulations. We found that both WZ and ZB phases of Cdo.sZn0.sS alloy exhibit phase segregation of Cd and Zn atoms at low temperature, which is consistent with the phase diagrams.展开更多
How to improve the probability of registration and precision of localization is a hard problem, which is desiderated to solve. The two basic approaches (normalized cross-correlation and phase correlation) for image re...How to improve the probability of registration and precision of localization is a hard problem, which is desiderated to solve. The two basic approaches (normalized cross-correlation and phase correlation) for image registration are analysed, two improved approaches based on spatial-temporal relationship are presented. This method adds the correlation matrix according to the displacements in x- cirection and y- directions, and the registration pose is searched in the added matrix. The method overcomes the shortcoming that the probability of registration decreasing with area increasing owing to geometric distortion, improves the probability and the robustness of registration.展开更多
A phase-shifting digital holography scheme developed to investigate internal defects in artworks is described. Phase-shifting is utilized to obtain a clear reconstructed object wave from a rough surface texture. A rev...A phase-shifting digital holography scheme developed to investigate internal defects in artworks is described. Phase-shifting is utilized to obtain a clear reconstructed object wave from a rough surface texture. A reverse-transform algorithm is employed to reconstruct the object wave on its original position of unknown distance or the imaging position from the object wave information on the holographic plane. To get the clearest reconstruction the exact registration of the unknown distance is determined by applying the intensity sum as the auto-focusing function, The spatial resolution of the reconstruction image is also investigated for a variety of affecting factors. Laboratory results of reconstruction images under deformation are presented.展开更多
基金supported by the National Natural Science Foundation of China (Grant No. 60878048)the China Postdoctoral Science Foundation (Grant No. 20080440898)
文摘Liquid crystal spatial light modulator （LCSLM） realizing equal-intensity multiple beams often has some features, i.e., phase valley between two adjacent pixels, flybaek region when phase decreases immediately from 2~r to 0, and inevitable backplane curvature, which are different from those of most conventional diffractive optical elements （DOEs）, such as static DOEs. For optimal intensity uniformity, equal-intensity multi-beam generation must be considered for these artifacts. We present a tunable-grating method in which the intensity uniformity can be improved by considering the LCSLM artifacts. For instance, tuning phase modulation depth of the grating, called isosceles triangle multilevel phase grating （ITMPG）, can be used not only to improve the intensity uniformity, but also to fast steer four beams with narrow beamwidths, determined by the same effective aperture of ITMPG. Improved intensity uniformity and high relative diffraction efficiency are demonstrated through experiments with phase-only LCSLM.
基金Project supported by the National Natural Science Foundation of China(Grant No.11274125)
文摘We investigate the co-propagation of a strong pump beam and a weak signal beam in lead glass, and find that the large phase shift of the strongly nonlocal spatial optical soliton （SNSOS） can be realized via cross-phase modulation. The theoretical study suggests a synchronous propagation of the pump SNSOS and the signal SNSOS under the required initial condition. A π-phase shift of the signal SNSOS is experimentally obtained by changing the power of the pump SNSOS by about 13 mW around the soliton critical power, which agrees qualitatively with our theoretical prediction. The ratio of the phase shift rate of the signal SNSOS to that of the pump SNSOS shows a close match to the reciprocal of the ratio between their wavelengths.
文摘Using a space filled with black-body radiation, we derive a generalization for the Clausius-Clapeyron relation to account for a phase transition, which in-volves a change in spatial dimension. We consider phase transitions from dimension of space, n, to dimension of space, (n - 1), and vice versa, from (n - 1) to n -dimensional space. For the former we can calculate a specific release of latent heat, a decrease in entropy, and a change in volume. For the latter, we derive an expression for the absorption of heat, the increase in entropy, and the difference in volume. Total energy is conserved in this transformation process. We apply this model to black-body radiation in the early universe and find that for a transition from n = 4 to (n - 1) = 3, there is an immense decrease in entropy accompanied by a tremendous change in volume, much like condensation. However, unlike condensation, the volume change is not three-dimensional. The volume changes from V4, a four-dimensional construct, to V3, a three-dimensional entity, which can be considered a subspace of V4. As a specific example of how the equation works, we consider a transition temperature of 3 × 1027 Kelvin, and assume, furthermore, that the latent heat release in three-dimensional space is 1.8 × 1094 Joules. We find that for this transition, the internal energy densities, the entropy densities, and the volumes assume the following values (photons only). In four-dimensional space, we obtain, u4 = 1.15×10125 J? m-4, s4 = 4.81×1097 J? m-4? K-1, and V4 = 2.14×10-31 m4. In three-dimensional space, we have u3 = 6.13×1094 J? m-3, s3 = 2.72×1067 J? m-3? K-1, and V3 = 0.267 m3. The subscripts 3 and 4 refer to three-dimensional and four-dimensional quantities, respectively. We speculate, based on the tremendous change in volume, the explosive release of latent heat, and the magnitudes of the other quantities calculated, that this type of transition might have a connection to inflation. With this work, we prove that space, in and of itself, has an inherent energy content. This is so because giving up space releases latent heat, and buying space costs latent heat, which we can quantify. This is in addition to the energy contained within that space due to radiation. We can determine the specific amount of heat exchanged in transitioning between different spatial dimensions with our generalized Clausius-Clapeyron equation.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11271158,11574117,and 61575077)
文摘The spatial distribution in high-order harmonic generation（HHG） from the asymmetric diatomic molecule He H^（2＋） is investigated by numerically solving the non-Born–Oppenheimer time-dependent Schr？dinger equation（TDSE）. The spatial distribution of the HHG spectra shows that there is little contribution in HHG around the geometric center of two nuclei（z = 1.17 a.u.） and the equilibrium internuclear position of the H nucleus（z = 3.11 a.u.）. We demonstrate the carrier envelope phase（CEP） effect on the spatial distribution of HHG in a few-cycle laser pulse. The HHG process is investigated by the time evolution of the electronic density distribution. The time–frequency analysis of HHG from two nuclei in HeH^（2＋） is presented to further explain the underlying physical mechanism.
基金Project supported by the National Natural Science Foundation of China(Grant No.51271100)the National Basic Research Program of China(Grant No.2012CB825702)the Special Funding in the Project of the Taishan Scholar Construction Engineering
文摘Molecular dynamics simulations are performed to investigate the liquid-liquid phase transition （LLPT） and the spatial heterogeneity in A1-Pb monotectic alloys. The results reveal that homogeneous liquid AI-Pb alloy undergoes an LLPT, separating into Al-rich and Pb-rich domains, which is quite different from the isocompositional liquid water with a transition between low-density liquid （LDL） and high-density liquid （HDL）. With spatial heterogeneity becoming large, LLPT takes place correspondingly. The relationship between the cooling rate, relaxation temperature and percentage of A1 and the spatial heterogeneity is also reported. This study may throw light on the relationship between the structure heterogeneity and LLPT, which provides novel strategies to control the microstructures in the fabrication of the material with high performance.
基金supported by the National Natural Science Foundation of China (Grant No 10574097)the Youth Foundation of University of Electronics Science and Technology of China
文摘By using the generalized Debye diffraction integral, this paper studies the spatial correlation properties and phase singularity annihilation of apertured Gaussian Schell-model （GSM） beams in the focal region. It is shown that the width of the spectral degree of coherence can be larger, less than or equal to the corresponding width of spectral density, which depends not only on the scalar coherence length of the beams, but also on the truncation parameter. With a gradual increase of the truncation parameter, a pair of phase singularities of the spectral degree of coherence in the focal plane approaches each other, resulting in subwavelength structures. Finally, the annihilation of pairs of phase singularities takes place at a certain value of the truncation parameter. With increasing scalar coherence length, the annihilation occurs at the larger truncation parameter. However, the creation process of phase singularities outside the focal plane is not found for GSM beams.
基金Project supported by the National Natural Science Foundation of China (Grant No. 10847110)
文摘Various pattern evolutions are presented in one- and two-dimensional spatially coupled phase-conjugate systems （SCPCSs）. As the system parameters change, different patterns are obtained from the period-doubling of kink-antikinks in space to the spatiotemporal chaos in a one-dimensional SCPCS. The homogeneous symmetric states induce symmetry breaking from the four corners and the boundaries, finally leading to spatiotemporal chaos with the increase of the iteration time in a two-dimensional SCPCS. Numerical simulations are very helpful for understanding the complex optical phenomena.
基金Project supported by the National Natural Science Foundation of China （Grant Nos 10575740, 90503010, 60478029 and 10634060） and the National Basic Research Program of China （Grant No 2005CB724508）. The authors would like to thank Professor Wu Ying for stimulating discussion and encouragement.
文摘This paper obtains the exact analytical solution of atomic Raman-Nath diffraction in the coordinate representation and discusses the influence of different initial conditions and detunings on the atomic spatial population distribution. The phase difference between the dipole matrix element and initial atomic population may influence the atomic spatial population distribution after diffraction, which has never been discussed before as far as we know. It offers a method to measure the phase by the spatial population distribution, which is interesting in the study of quantum optics.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.115074045 and 11204187)the Natural Science Foundation of Jiangsu Province,China(Grant No.BK20131284)
文摘We study the possible topological phase in a one-dimensional（1D） quantum wire with an oscillating Rashba spin–orbital coupling in real space. It is shown that there are a pair of particle–hole symmetric gaps forming in the bulk energy band and fractional boundary states residing in the gap when the system has an inversion symmetry. These states are topologically nontrivial and can be characterized by a quantized Berry phase ±π or nonzero Chern number through dimensional extension. When the Rashba spin–orbital coupling varies slowly with time, the system can pump out 2 charges in a pumping cycle because of the spin flip effect. This quantized pumping is protected by topology and is robust against moderate disorders as long as the disorder strength does not exceed the opened energy gap.
基金supported by the National Natural Science Foundation of China(Grant Nos.11164014 and 11364025)Gansu Science and Technology Pillar Program,China(Grant No.1204GKCA057)
文摘The first-principles calculations based on density functional theory combined with cluster expansion techniques and Monte Carlo （MC） simulations were used to study the phase diagrams of both wurtzite （WZ） and zinc-blende （ZB） Cdl_xZnxS alloys. All formation energies are positive for WZ and ZB Cdl-xZnxS alloys, which means that the Cdl-xZnxS alloys are unstable and have a tendency to phase separation. For WZ and ZB Cdl_xZnxS alloys, the consolute temperatures are 655 K and 604 K, respectively, and they both have an asymmetric miscibility gap. We obtained the spatial distributions of Cd and Zn atoms in WZ and ZB Cd0.sZn0.sS alloys at different temperatures by MC simulations. We found that both WZ and ZB phases of Cdo.sZn0.sS alloy exhibit phase segregation of Cd and Zn atoms at low temperature, which is consistent with the phase diagrams.
文摘How to improve the probability of registration and precision of localization is a hard problem, which is desiderated to solve. The two basic approaches (normalized cross-correlation and phase correlation) for image registration are analysed, two improved approaches based on spatial-temporal relationship are presented. This method adds the correlation matrix according to the displacements in x- cirection and y- directions, and the registration pose is searched in the added matrix. The method overcomes the shortcoming that the probability of registration decreasing with area increasing owing to geometric distortion, improves the probability and the robustness of registration.
文摘A phase-shifting digital holography scheme developed to investigate internal defects in artworks is described. Phase-shifting is utilized to obtain a clear reconstructed object wave from a rough surface texture. A reverse-transform algorithm is employed to reconstruct the object wave on its original position of unknown distance or the imaging position from the object wave information on the holographic plane. To get the clearest reconstruction the exact registration of the unknown distance is determined by applying the intensity sum as the auto-focusing function, The spatial resolution of the reconstruction image is also investigated for a variety of affecting factors. Laboratory results of reconstruction images under deformation are presented.
