Based on nonlinear Schrodinger equation, the properties of two-source-coupled-inputed soliton and the interaction between such soli tons and the first order solitons are numerically investigated by the split-step Fourier transformation method. A tentative idea of triply optical soliton communication system is proposed and disscussed, which made the relay distance further extended with the information increased by 1.6 factor. Besides, the high power input of the light source is not necessary by using such solitons.

The wave reflection and transmission properties in the dimension-Changable 2/R cantor fructal layers are analysed. The formulae determining the reflection and transmission spectra with a self-similar procedure are given. This new physical reflection spectra with a quasi-self-similarity is significant for certain applications.

Based on the nonlinear schodinger equation, the interaction between a couple of second order or quasi-second order optical solitons is numerically investigated by the split-step Fourier transformation method. This let us have a good understanding of the properties in the interactions, which is referential for the utilization of second solitions to communication.

A method with a set of improved basis functions in vaouum-jellium region for Film-LAPW, method suited to jellium/slab model is proposed. The calculations for examination of this method, with three layers of W slab to simulate the W(100) surface covered with Cs overlayer is made. The results are more stabilized and accurate, and are much closer to experiments. The contribution weights of each vaccum basis function to the wave function is analysed.