The coherent interactions between one-dimensional discrete spatial optical solitons, derived by Petviashvili iteration method, are numerically investigated with the split-step beam propagation method in light-induced planar waveguide arrays. The influences of the initial phase difference, the soliton peak intensities, the periods and intensities of the writing beams for waveguide arrays, and the amplitudes of the externally bias fields on the interactions between two discrete solitons are analyzed in detail. It is found that the interactions between two parallel discrete solitons with different initial phase differences behave in a way similar to that encountered in continuous media, i.e., in-phase (out-of-phase) discrete solitons attract (repel) each other, and the intermediates are always accompanied with energy transfer. In addition, the interaction processes are influenced by the variations of soliton peak intensities, the configurations of the light-induced waveguide arrays, and the amplitudes of the external bias fields.

The nonlinear hot image effect from phase scatterer in a high-power laser system has been investigated theoretically and numerically. According to the Fresnel-Kirchhoff diffraction integral and nonlinear paraxial wave equation, we derive the functional relationship of the intensity of hot image and its location. It is shown that the image intensity is likely several times larger than that from amplitude scatterer, and the location is situated in the equidistant downstream plane of the scatterer in an optical component located upstream from a nonlinear element. Good agreements are shown between the theoretical prediction and the computer codes developed for ns-pulse propagation simulations. The results indicate that the formation of hot image is akin to the real-time, in-line and volume-phase holographic imaging.

Based on the split-step-Fourier-transform and the diffraction theory of hot-image model we made the simulation of the evolvement of hot-image in case of thick nonlinear medium. The changes of some parameters influencing the intensity and location of hot-image, such as the modulation coefficient (including amplitude modulation and phase modulation), the distance between scatterer and the front surface of nonlinear medium, the size of the scatterer, the intensity of incident beams and so on, were detailedly analysed respectively. Numerical results were found to be in agreement with analytical theory for the changes in modulation coefficient and the intensity of incident beams, but not in agreement with analytical theory for the changes in the size of the scatterer. Moreover, when the distance between scatterer and the front surface of nonlinear medium is zero, hot-image will also be found on the back surface of nonlinear medium.

A novel high birefringence photonic crystal fiber (PCF) was proposed and the properties of this type of PCF were investigated with full vector finite difference frequency domain method. According to the results of numerical analysis, the two orthogonally polarized states of the fundamental mode become non-degenerate in the fiber and show strong linear polarization. The polarization properties are strongly dependent on the structure parameters of this PCF. Through choosing suitable relative structure parameters, it may exhibit birefringence as high as the order of 10-2, at least one order of magnitude higher than that of the conventional D-type and panda-type polarization-maintaining fiber. It is shown that it may also exhibit ideal dispersion effect in a properly designed geometrical structure of PCF. So this type of PCF can be effectively used to fabricate polarization-preserving fiber and correlative fiber elements with special dispersion and polarization characteristics.

With the optical interference and exciton diffusion principle, the mechanism and process in a typical organic donor-acceptor solar cell are analyzed and simulated in virtue of a model established by MATLAB software. The effect of the organic film's thickness on the characteristics of organic solar cell is analyzed quantitatively, photo-absorptivity and exciton diffusivity are optimized by confining the thickness of organic active layers. The reliability of optimized model is validated by experiment.