Recalibration of the binding energy of hypernuclei measured in emulsion experiments and its implications

The Λ separation energy for Λ hypernuclei,denoted B_Λ,measured in 1967,1968,and 1973 are recalibrated using the current best estimates of the mass of particles and nuclei.The recalibrated B_Λ are systematically larger(except in the case of _Λ~6He) than the originally published values by about 100 keV.The effect of this level of recalibration is very important for light hypemuclei,especially for the hypertriton.The early B_Λ values measured in1967,1968,and 1973 are widely used in theoretical research,and the new results provide better constraints for the conclusions of such studies.     

Fluctuations of optical phase of diffracted light for Raman–Nath diffraction in acousto–optic effect

The Raman–Nath diffraction in acousto–optic effect was studied theoretically and experimentally in the paper.Up to now,each order of diffracted light in Raman–Nath diffraction was still considered simply to be just frequency-shifted and to be a plane wave.However,we find that the phase and frequency shifts occur simultaneously and individually in Raman–Nath diffraction.The findings demonstrate that,in addition to the frequency shift,the optical phase of each order of diffracted light is also shifted by the sound wave and fluctuates with the sound wave and is related to the location in the acoustic field from which the diffracted light originates.As a result,the wavefront of each order of diffracted light is modulated to fluctuate spatially and temporally with the sound wave.Obviously,these findings are significant for applications of Raman–Nath diffraction in acousto–optic effect because the optical phase plays an important role in optical coherence technology.     

Experimental Study of Effect of Medium Boundary on Light Distribution in Tissue Phantoms

An experimental method for investigating the effect of medium boundary on distributions of light in the biological tissue phantom intralipid is presented. Measurements of distributions of light in intralipid-10% suspensions at 633 nm are described, in which a narrow collimated beam is incident on the surface of the phantoms and into the different depths inside of the phantoms. The experimental results show that the effect of the boundary of the medium on the curves geometry of light distributions is trivial, but the effect on intensity of scattering light is obvious, the maximal relative change of the energy fluence reaches 53.8% and the position of the peak of the energy fluence curve has a shift of 1.1 mm in the reverse direction of incident light for the phantom with albedo a=0.998, and the effect of the boundary is decreased with the increase of the absorption coefficients of tissue phantoms. The experimental results were analysed by the diffusion theory. These studies will be helpful for further understandings of the relation between the boundary of biological tissue and the distribution of light in tissue.     

Group Velocity Reduction of Light Pulses in Photorefractive Two-Wave Mixing

We show theoretically that the group velocity of light pulses can be reduced significantly by use of the steep dispersion properties of the phase coupling effect in the photorefractive two-wave mixing process. The group velocity of light pulses of the order of 0.1 m/s can be achieved in typical photorefractive BSO crystals with an appropriate externally applied electric field and moving gratings of appropriate speeds. It is also shown that the slowly propagating light pulses can be set to be amplified after passing through the photorefractive material.     

Silver clusters insert into polymer solar cell for enhancing light absorption

As an employment of surface plasmonic effect, the consequence of insertion of a layer of Ag clusters into polymer solar cell on the enhancement of light absorption and power conversion efficiency is investigated. Optical analysis based on the finite-difference time-domain (FDTD) is performed with experiments to evaluate the effect of the interaction between the Ag clusters and incident light on light absorption in polymer solar cell. Ag clusters modify the light wave vector and the electromagnetic field inside the device is redistributed and enhanced. As a result, polymer solar cells achieve an overall increase in absorption, short-circuit current density, and power conversion efficiency.     

Process-controllable modulation of plasmon-induced transparency in terahertz metamaterials

Recently reported plasmon-induced transparency(PIT)in metamaterials endows the optical structures in classical systems with quantum optical effects.In particular,the nonreconfigurable nature in metamaterials makes multifunctional applications of PIT effects in terahertz communications and optical networks remain a great challenge.Here,we present an ultrafast process-selectable modulation of the PIT effect.By incorporating silicon islands into diatomic metamaterials,the PIT effect is modulated reversely,depending on the vertical and horizontal configurations,with giant modulation depths as high as 129%and 109%.Accompanied by the enormous switching of the transparent window,remarkable slow light effect occurs.     

Dynamic control of retrieval contrast in a Λ-type atomic system

We propose an efficient scheme for optimizing the optical memory of a sequence of signal light pulses in a system of ultracold atoms in Λ configuration. The memory procedure consists of write-in, storage, and retrieval phases. By applying a weak microwave field in the storage stage, additional phase-dependent terms are included, and the contrast of the output signal pulses can be dynamically controlled (enhanced or suppressed) through manipulating the relative phase φ between optical and microwave fields. Our numerical analysis shows that the contrast is enhanced to the most extent when φ=1.5π. In addition, the contrast is in proportion to the Rabi frequency of the microwave field with a certain relative phase.     

Light—induced nonlinear effects of dispersion relation of ultracold Bose gas

We have investigated the optical properties of Λ-configuration ultracold dense Bose gas interacting with two laser pulses, which usually result in electromagnetically induced transparency. With the nonrelativistic quantum electrodynamics and taking into account the atomic dipole－dipole interaction and local field effect, we have derived the Maxwell－Bloch equations of the system. The dispersion relation of an ultracold Bose gas has been obtained and the light-induced nonlinear effects have been analysed. The light-induced nonlinear effects are different from the effects induced by two-body collision of Bose－Einstein condensation atoms which have a frequency shift of transparent window.     

Alternative methods for measurement of the global polarization of Λhyperons

We propose alternative methods for measurement of the global polarization of Λ hyperons. These methods involve event averages of proton and Λ momenta in the laboratory frame. We carry out simulations using these methods and show that all of them work equally well in obtaining the global polarization of Λ hyperons.     

Two-Dimensional Photovoltaic Dark Spatial Solitons of Partially Spatially Incoherent Light

We report a successful experimental observation of two-dimensional photovoltaic dark solitons in an anisotropic crystal with partially spatially incoherent light beams. This kind of solitons results from the bulk photovoltaic effect， which depends on the direction of propagation of the optical beam and on the orientation of the intensity gradient, with respect to the principal axes of the crystal     

Polarization Conversion of Single Photon via Scattering by a Λ System in a Semi-Infinite Waveguide

We theoretically investigate single-photon polarization conversion via scattering by an atom with Λ configuration coupled to a semi-infinite waveguide and discuss the two cases in which the Λ system is non-degenerated and degenerated. By applying the hard-wall boundary condition of the semi-infinite waveguide, it is found that singlephoton polarization conversion can be realized with unit probability for both cases under the ideal condition.Together with the polarization conversion, the frequency conversion of a single photon can also be realized with unit probability in the ideal case if the Λ system is not degenerated.     

Production of Λ-hypernuclei in A(p,K~ )ΛB reactions

The production of Λ-hypernuclei in the A(p,K )ΛB reaction is investigated in the framework of the distorted wave impulse approximation(DWIA). The total cross sections and differential cross sections for various nuclear targets are calculated with an elementary process pN→NKΛ where the additional contributions from the N*(1535) resonance and the final state interaction between p and Λ are included. The dependence of the production cross sections of Λ-hypernuclei on the phenomenological nuclear density and the nucleon number in the target, as well as the distortion effect of the incident proton and outgoing kaon, are also explored. It is shown that the distortion effect tends to decrease the cross sections by a factor of about 3—10. The production cross sections are sensitive to the adopted nuclear density.     

Tuning Characteristics of Frequency Difference for Zeeman—Birefringence He—Ne Dual Frequency Laser

Characteristics of frequency difference tuning of Zeeman-birefringence He-Ne dual frequency lasers (ZBDFLs) are explored.We design an automatic system of tuning cavity and power detection,which can tune the laser cavity and record the tuning curves of light power and frequency difference simultaneously.A synthetic phenomenon by Zeenman effect,mode pulling effect and birefringence effect is verified to exist in ZBDFLs.By analysing the tuning behaviour,this synthetic phenomenon is discovered and qualitatively explained for the first time.     

Switching the direction of spin accumulation in the spin Hall effect of light by adjusting the optical axis of an uniaxial crystal

We theoretically and experimentally investigate a switchable spin Hall effect (SHE) of light in reflection near the Brewster angle at an air-uniaxial crystal interface. We find a large transverse spin splitting near the Brewster angle, whose sign can be altered by rotating the optical axis. As an analogy of the SHE in an electronic system, a switchable spin accumulation in the SHE of light is detected. We are able to switch the direction of the spin accumulation by adjusting the optical axis angle of the uniaxial crystal. These findings may give opportunities for photon spin manipulating and developing a new generation of nano-photonic devices.     

Influence of Photon Mass on Vacuum Birefringence Experiment

Influence of photon mass on vacuum birefringence experiment is analysed according to the nonlinearities of vacuum quantum electrodynamics for the light propagation through an intense electromagnetic field. It is shown that although the photon mass will cause a change of the refractive indices n┴ and nⅡ of vacuum birefringence, the difference nⅡ - n┴ is unchanged, which means that the effect of photon mass cannot be observed in vacuum birefringence experiment.     

Temperature Dependence of Photoinduced Birefringence in an Azobenzene Polymer

The photoinduced birefringence in an azobenzene polymer is investigated at different temperatures between -20℃ to 50℃. It is found that there is a peak value of photoinduced birefringence in the temperature dependence of the photoinduced birefringence under a certain pumping intensity. With the pump light in 90mW/cm^2, the peak value of the photoinduced birefringence appeared at about 0℃ C. The effect of temperature on the photoinduced birefringence is discussed using the competition mechanism between the photoinduced reorientation and the thermal random motion.     

Production of Λ-hypernuclei in A(p,K+)ΛB reactions

The production of Λ-hypernuclei in the A(p, K⁺)_ΛB reaction is investigated in the framework of the distorted wave impulse approximation(DWIA). The total cross sections and differential cross sections for various nuclear targets are calculated with an elementary process pN→NKΛ where the additional contributions from the N^*(1535) resonance and the final state interaction between p and Λ are included. The dependence of the production cross sections of Λ-hypernuclei on the phenomenological nuclear density and the nucleon number in the target, as well as the distortion effect of the incident proton and outgoing kaon, are also explored. It is shown that the distortion effect tends to decrease the cross     

Ground state properties of a Bose－Einstein condensate confined in an anharmonic external potential

In light of the interference experiment of Bose－Einstein condensates, we present an anharmonic external potential model to study ground state properties of Bose－Einstein condensates. The ground state energy and the chemical potential have been analytically obtained, which are lower than those in harmonic trap. Additionally, it is found that the anharmonic strength of the external potential has an important effect on density and velocity distributions of the ground state for the Thomas－Fermi model.     

The correlation of the energy resolution of incident light with the measured reflectance of multilayers

This paper presents an expression for describing the correlation of the energy resolution of incident light with the measured reflectance of multilayers, and gives a new method for calculating the polychromatic-light reflectance of multilayers. Using this method we give the reflectance spectrum of some multilayers in the case in which the incident light is polychromatic. The theoretical analysis shows that for the multilayers of a given design the peak reflectance of the polychromatic light is smaller than that of the monochromatic light, but no-peak reflectance of the polychromatic light is bigger than that of the monochromatic light. Further, the measured reflectance spectrum will be a line if the energy resolution is less than a decided value. The shorter the design-wavelength of the multilayer, the stronger the effect of the energy resolution on the reflectance.