She Wei-Long

Incoherently Coupled Grey Photovoltaic Spatial Soliton Families

A theory is developed for incoherently coupled grey photovoltaic soliton families in unbiased photovoltaic crystals. Both the properties and the forming conditions of these soliton families are discussed in detail. The theory can also be used to investigate the dark photovoltaic soliton families. Some relevant examples are presented, in which the photovoltaic-photorefractive crystal is of lithium niobate type.

Quantization of light energy directly from classical electromagnetic theory in vacuum

Very recently we present a theory [Wei-long She, Chin. Phys. 14, 2514(2005); Online: this http URL http://arxiv.org/abs/quant-ph/0512097] to show that the quantization of light energy in vacuum can be derived directly from classical electromagnetic theory through the consideration of statistics based on classical physics and reveal that the quantization of energy is an intrinsic property of light as a classical electromagnetic wave and has no need of being related to particles. In this theory a key concept of stability of statistical distribution was involved. Here is a note to the theory, which would be helpful for understanding the concept of stability of statistical distribution.It is currently believed that light quantum or the quantization of light energy is beyond classical physics and the picture of wave–particle duality, which was criticized by Einstein but has attracted a number of experimental researches, is necessary for the description of light. It is shown in this paper, however, that the quantization of light energy in vacuum, which is the same as that in quantum electrodynamics, can be derived directly from the classical electromagnetic theory through the consideration of statistics based on classical physics. Therefore, the quantization of energy is an intrinsic property of light as a classical electromagnetic wave and has no need of being related to particles.

Generalized Theory of One-Dimensional Steady-State Optical Spatial Solitons

We present a generalized soliton theory based on the one-dimensional generalized nonlinear Schrodinger equation, from which one can easily obtain the bright, dark, and grey soliton waveforms, and their existence curves. We show that the forming conditions of spatial solitons are directly dependent on the relationship between the index perturbation and the intensity, no matter whether the index perturbation is positive or negative. Some relevant examples are presented when the solitons are supported by the photoisomerization nonlinearity.

Internal mode of incoherent photovoltaic vector solitons

The internal modes of incoherent vector solitons (IVSs) in photovoltaic photorefractive materials are investigated in the framework of coupled nonlinear Schrodinger equations. It is found that there is a pair of internal modes corresponding to a bright–bright IVS. The propagation dynamics of the bright-bright IVS perturbed by the internal modes is simulated by numerical method.

Transient photoluminescence spectra of GaAs/AlGaAs quantum wells, quantum well wires, and quantum well boxes

The interaction of the electrons with the phonons in GaAs/AlGaAs quantum wells, quantum well wires, and quantum well boxes has been studied by meansuring their time resolved photoluminescence (PL) spectra. In the quantum well (QW) system, relaxation time of the electron energy of the narrower well is shorter than that of the wider well. It is attributed to the stronger interaction of the electrons with the interface mode phonons. In the QW wires and QW boxes, the shortening of the relaxation time is obvious. It is due to the stronger electron-phonon interaction caused by the reduction of screening effect. Our experiments also demonstrated the incident laser intensity dependence of the relaxation time.

Movement of a millimeter-sized oil drop pushed by optical force*

We show experimentally that when an unfocused continuous wave (CW) laser beam is obliquely incident onto the surface of a millimeter-sized mineral oil drop on sucrose solution, it will exert a pushing force on the oil drop, making it move forwards along the surface of the sucrose solution. However, after a period of time, the oil drop stops moving. This can be explained as the phenomenon caused by the change of Abraham momentum, the optical gradient force, and friction together.

Bloch oscillation and Landau–Zener tunnelling in a modulated optical lattice in a photovoltaic photorefractive crystal

We theoretically study the beam dynamical behaviour in a modulated optical lattice with a quadratic potential in a photovoltaic photorefractive crystal. We find that two different Bloch oscillation patterns appear for the excitation of both broad and narrow light beams. One kind of optical Landau–Zener tunnelling also appears upon the Bloch oscillation and can be controlled by adjusting the parameter of the optical lattice. Unlike the case of linear potential, the energy radiation due to Landau–Zener tunnelling can be confined in modulated lattices of this kind. For high input intensity levels, the Landau–Zener tunnelling is suppressed by the photovoltaic photorefractive nonlinearity and a symmetry breaking of beam propagation from the modulational instability appears.

A Vector Theory on Spatial Solitons in Kerr Media

A new vector theory which concerns the necessary and sufficient conditions of the self-trapping of a linearly polarized light beam in Kerr media is presented after a generalization of Fermats principle. It is rigidly proven under these conditions that 1+1-dimensional spatial solitons can exist in Kerr media but 2+1-dimensional solitons cannot. A new form of the general equation for 1+1-dimensional solitons in Kerr media is put forward and some of its solutions have been obtained.

Pattern Formation and Quasicrystal Structure in Azobenzene Polymer Film

Pattern formation in azobenzene polymer film by degenerate four-wave mixing is reported. Island arrays with specific patterns are analyzed with scanning electron microscopy and polarizing optical microscopy. It is demonstrated that the control of photo-induced nanostructure sized micropattern in the nonlinear organic film is possible by using properly polarized writing beams with the total incident power exceeding a certain threshold.

Mutual Quenching of Self-Pumped Phase Conjugation by Incoherent ps Laser Pulses

When two beams of incoherent cw mode-locked ps laser pulses were incident upon opposite faces perpendicular to the a-axis of a Cu-doped KNSBN crystal, no mutually pumped phase conjugation as that generated by continuous waves was observed, however, the stronger laser beam generated its self-pumped phase conjugation which was weakened by the weaker one. When the intensities of the two beams were equal, self-pumped phase conjugation was completely quenched.