Numerical investigation on fundamental mode of PBG-PCF with six-fold rotation symmetry is carried out with full-vector plane wave and multipole method. Band gap of two-photonic crystal, constituting PBG-PCF, is determined by full-vector plane wave method. Frequency of possible existing fundamental modes(bound modes) are not only in band gap but also above line k₀α=βα. Radiation modes exist out of band gap. Multipole method is performed with input frequency as variables. Field distribution of fundamental mode is plotted by MATLAB. It indicates that fundamental modes do not exist in all possible domains. It gives a feasible method to find fundamental modes of PBG-PCF.

We apply effective dipole approximation to investigate the equivalent dielectric constant of inclusion and the effective response and optical absorption in composites media of metal spherical particles.The dielectric constant varies along the radius of the particles.ε_e exhibits a monotonic decrease with the power index n while the dielectric constant shows a power law gradation.The presence of the gradation in metal particles yields a resonant optical absorption peak.It shows red-shift with m_ω and m_ν of the metal-dielectric composites.

The solution of non-linear schr6diuger (NLS) equation including twophoton absorption in optical fibers with slowly decreasing dispersion,is given by using travelling wave method,and the solution for the propagation characteristics of dark soliton is also discussed in detail.

In this paper the approximate solution for NLS equation, including Raman Effect,by using common mathematics is given, and the Raman effect in the solution of the NLS equation is discussed in detail.

In this pater, using parametric transform method direct derive soliton wave equation of loss optical fibers and elementary soliton solution.