Critical Internuclear Separation of H+2 in Strong Light Field of Ti:s Laser

Image method was employed to study the ionization and dissociation behaviors of molecular hydrogen ions in the presence of strong Ti:s laser light. Besides the bond-softening and above-threshold dissociation phenomena, we found that the critical internuclear separation in Coulomb explosion process was dependent upon light intensity. The experimental and theoretical trends of this dependence were shown to be in a fairly good agreement. The light intensity range used was 1014～1016 W/cm2.     

Semiclassical Approach to Non-Sequential Double Ionization of Diatomic Molecules in Strong Laser Field

We develop a semiclassical model to describe the non-sequential double ionization of diatomic molecules in an intense linearly polarized field, achieving insight into the two-electron correlation effect in the ionization dynamics. Compared to the experimental data of nitrogen molecules, our model shows a good agreement in the tunnelling regime and a qualitative agreement in the over-barrier regime. We find that the classical collisional trajectories are the main source of the double ionization in the tunnelling regime. As a prediction of our theory, we also calculate the double ionization ratios of H2^2＋/H2^＋ for hydrogen molecules and predict a ratio less than that of nitrogen molecules.     

Imaging Internuclear Separation of H^＋2 in Configuration Space： Reduced Dimensionality Model

We present a method for obtaining the internuclear separation of diatomic molecular ion H^＋2 irradiated by attosecond-duration laser pulse, by computing the probability flux of wavefunction pattern of photoelectron in configuration space. In contrast to earlier means of attosecond-scale time-gating or taking ratio of image data in momentum space, our alternative is characterized by experimental feasibility. The numerical results of a reduceddimensionality model on hydrogenic ions corroborated our method are obtained and can be generalized to more complex molecular systems for inferring bond length or bond angle information.     

Tunable Sum Frequency Mixing of a Ti∶sapphire Laser and a Nd∶YAG Laser

1　Ｉｎｔｒｏｄｕｃｔｉｏｎ　　Ｔｉ∶ｓａｐｐｈｉｒｅｌａｓｅｒｉｓｔｈｅｍｏｓｔｗｉｄｅｌｙｔｕｎａｂｌｅｌａｓｅｒｉｎｔｈｅｃｕｒｒｅｎｔｌａｓｅｒｔｅｃｈｎｏｌｏｇｙａｎｄｈａｓａｔｕｎｉｎｇｒａｎｇｅｆｒｏｍ 0 .68ｔｏ 1 .1 μｍ .Ｓｏｉｔｉｓ ｑｕｉｔｅｉｍｐｏｒｔａｎｔａｎｄｕｓｅｆｕｌｗｉｔｈｎｏｎｌｉｎｅａｒｏｐｔｉｃａｌｆｒｅｑｕｅｎｃｙｃｏｎｖｅｒｓｉｏｎｔｅｃｈｎｏｌｏｇｙｔｏｅｘｐａｎｄｉｔｓｏｕｔｐｕｔｗａｖｅｌｅｎｇｔｈ .Ｎｏｎｌｉｎｅａｒｗａｖｅｌｅｎｇｔｈｃｏｎｖｅｒ…     

Tunable Sum Frequency Mixing of a Ti∶sapphire Laser and a Nd∶YAG Laser

In this paper the theoretical and experimental results of sum-frequency mixing of a Ti∶sapphire laser and a 1.064 μm Nd∶YAG laser are presented. By using two KTP crystals cut at θ=76° and 85° (φ=90° in both crystals), respectively, the sum-frequency mixing tuning range from 459.3 to 509.6 nm in one Ti∶sapphire laser setup is experimentally achieved. The maximum output energy was 14.6 mJ and the energy conversion efficiency was up to 15.2%.     

Effect of the Initial Laser Phase on the Interaction Between Relativistic Electron and Ultra－Intense Laser Field in a Strong Uniform Magnetic Field

We investigate the influence of the initial laser phase on the interaction between relativistic electron and ultraintense linear polarized laser field in a strong uniform magnetic field. It is found that the dynamic behaviour of the relativistic electron and the emission spectrum varies dramatically with different initial laser field phases.The effect of changing initial phase is contrary in the two parameter regions divided by the resonance condition.The phase dependence of the electron energy and velocity components are also studied. Some beat structure is found when the initial laser phase is zero and this structure is absent when the initial laser phase is a quarter of a period.     

Pondermotive Shift of Photoelectron Spectra in Intense Laser Field

In a recent experimental work on the excess photon detachment （EPD） of H^- ions [Phys. Rev. Lett. 87 （2001） 243001] it has been found that the ponderomotive shift of each EPD peak increases with the order of the EPD channel. By using a nonperturbative quantum scattering theory, we obtain the kinetic energy spectra for the differential detachment rate Mong the laser polarization for several laser intensities. It is demonstrated that higher order EPD peaks are produced mainly at relatively higher laser intensities. By calculating the overall EPD spectra with varying laser intensities, it is found that the ponderomotive shift of each EPD peak increases with the order of the EPD channel Our calculations are in good agreement with the experimental observation. It is found that different EPD channels occur mainly when the laser field reaches some values, thus the intensity distribution of the laser field is responsible for the varying ponderomotive shifts.     

Soliton Solutions of Bose-Einstein Condensate in Linear Magnetic Field and Time-Dependent Laser Field

With the help of symbolic computation, the tanh method is extended to find some new exact solutions of nonlinear Gross-Pitaevskii equation with weak bias magnetic and time-dependent laser fields. As a result, the bright and dark soliton solutions are obtained. In addition, some new soliton solutions in this model are found.     

Carbon Nitride Thin Films Deposited by Plasma Assisted Nd∶YAG Laser Ablation of Graphite in N_2 H_2 Atmosphere

1　Ｉｎｔｒｏｄｕｃｔｉｏｎ　　Ｔｈｅｓｙｎｔｈｅｓｉｓｏｆｃａｒｂｏｎｎｉｔｒｉｄｅｔｈｉｎｆｉｌｍｓｈａｓｂｅｅｎｔｈｅｓｕｂｊｅｃｔｏｆｉｎｔｅｎｓｅｓｔｕｄｙｓｉｎｃｅｔｈｅｔｈｅｏｒｅｔｉｃａｌ ｐｒｅｄｉｃａｔｉｏｎ[1,2 ] ａｎｄｅｘｐｅｒｉｍｅｎｔａｌｒｅａｌｉｚａｔｉｏｎ[3] ｏｆ β Ｃ3Ｎ4ｔｈｉｎｆｉｌｍｓ.Ｍａｎｙａｔｔｅｍｐｔｓｈａｖｅｂｅｅｎｍａｄｅｔｏｓｙｎｔｈｅｓｉｚｅｔｈｉｓｍａｔｅｒｉａｌｂｙ ｐｈｙｓｉｃａｌａｎｄｃｈｅｍｉｃａｌｍｅｔｈｏｄｓ ,ｓｕｃｈａｓｒｅａｃｔ…     

Gravitational Lensing in the Strong Field Limit for Kar’s Metric

In this paper we calculate the strong field limit deflection angle for a light ray passing near a scalar charged spherically symmetric object, described by a metric which comes from the low-energy limit of heterotic string theory. Then, we compare the expansion parameters of our results with those obtained in the Einstein’s canonical frame, obtained by a conformal transformation, and we show that, at least at first order, the results do not agree.     

Demonstration of Color Separation with 2ω KDP Wedge in High Power Laser Facilities

A 2ω wedge design is proposed with KDP crystal to disperse the unconverted light away from the target in a high power laser facility for inertial confinement fusion. The ultraviolet B-integral problem is released, and about 1.2 times in color separation angle is achieved according to both theoretical and experimental investigations when compared with conventional 3ω wedge. The frequency conversion etgciency is unaffected when the wedge is along the non-sensitive axis of the tripler.     

Enhancement of Bichromatic High-Order Harmonic Generation by a Strong Laser Field and Its Third Harmonic

We investigate high-order harmonic generation （HHG） in a linearly polarized bichromatic field composed of a fundamental laser field with frequency w and an additional laser field with frequency 3w. The numerical results show that it is possible to enhance the intensity of most high harmonics in orders of magnitude. A most striking feature in the enhancement is that the intensity of several special high harmonics is practically impaired as compared with that in the monochromatic case. The qualitative explanation to the great enhancement is that the additional high-frequency field can provide new transition paths for electrons to reach the continuum. The relative phase between the fundamental field and its third harmonic field also affects the intensity of high-order harmonics near the cutoff efficiently.     

Development of the Fast Ionization Gauge in a Strong Magnetic Field

The neutral gas pressure near plasma or divertor plates are very important for the plasma-wall interaction, which determines the operating mode of divertor and confining performances of plasma in tokamaks. A fast ionization gauge (fast gauge) is designed for this purpose in the HL-2A tokamak.     

Two-Dimensional Collimation of an Atomic Beam in a Diffuse Light Field

Ｔｗｏ－ＤｉｍｅｎｓｉｏｎａｌＣｏｌｌｉｍａｔｉｏｎｏｆａｎＡｔｏｍｉｃＢｅａｍｉｎａＤｉｆｆｕｓｅＬｉｇｈｔＦｉｅｌｄ￥ＬＩＦｏｓｈｅｎ；ＣＨＥＮＨｏｎｇｘｉｎ；ＣＡＩＷｅｉｑｕａｎｇ；ＬＩＵＬｉａｎｇ；ＳＨＵＷｅｉ；ＷＡＮＧＹｕｚｈｕ（Ｊｏｉｎｔ...     

Bifurcation of Dicke Model Driven by Laser Field and Scaling Theory of Critical Exponents Far from Equilibrium

ＢｉｆｕｒｃａｔｉｏｎｏｆＤｉｃｋｅＭｏｄｅｌＤｒｉｖｅｎｂｙＬａｓｅｒＦｉｅｌｄａｎｄＳｃａｌｉｎｇＴｈｅｏｒｙｏｆＣｒｉｔｉｃａｌＥｘｐｏｎｅｎｔｓＦａｒｆｒｏｍＥｑｕｉｌｉｂｒｉｕｍＯＵＦａ（ＣＣＡＳＴ（ＷｏｒｌｄＬａｂｏｒａｔｏｒｙ）Ｐ．Ｏ．...     

Upper Critical Field of a Two-Band SrFe2 − xNixAs2 Superconductor

JETP Letters - The upper critical field of an iron-based SrFe2 − xNixAs2 superconductor single crystal is measured for the first time in longitudinal and transverse magnetic fields up to 16 T...     

Effect of Laser Pulse Shape on the Wake Field in Relativistic Intense Laser—Plasma Interaction

We study the effect of laser pulse shape on the plasma wake field driven by an intense laser beam.It is found that the modified asymmetric laser pulse shape with a sharply rising front and broad falling back,due to some nonlinear interactions of an intense laser pulse with plasmas,can significantly enhance the magnitude of the wake field.     

The Properties of Light Pressure Force with High Order in Laser Fields

1　Ｉｎｔｒｏｄｕｃｔｉｏｎ　　Ｉｎｒｅｃｅｎｔｙｅａｒｓ,ｂｏｔｈｔｈｅｔｈｅｏｒｅｔｉｃａｌａｎｄｅｘｐｅｒｉｍｅｎｔａｌｉｎｖｅｓｔｉｇａｔｉｏｎｓｏｎｌａｓｅｒｃｏｏｌｉｎｇａｎｄｔｒａｐｐｉｎｇｈａｖｅｂｅｃｏｍｅｏｎｅｏｆｔｈｅｍａｊｏｒｆｉｅｌｄｓｉｎａｔｏｍｉｃ,ｍｏｌｅｃｕｌａｒａｎｄｏｐｔｉｃａｌ ｐｈｙｓｉｃｓ[1～ 8] .Ｔｈｅｄｅｖｅｌｏｐｍｅｎｔｏｆｌａｓｅｒｃｏｏｌｉｎｇａｎｄｔｒａｐｐｉｎｇｔｅｃｈｎｏｌｏｇｙｉｓｉｍｐｏｒｔａｎｔｆｏｒｔｈｅａｐｐｌｉｃａｔｉｏｎｓｓｕ…