Recently

there has been significant interest in studies of the localization of electrom agnetic waves (EW)in photonic band-gap(PBG)matcriale.The interest is partially due to the fact that the interactions between the electrons don't exist any longer and the experiments can be performed at the room temperature.Furthermore

the special property of the control of propagation of light in the PBG has patential applications in many potical devices.One or multiple applications in the fabrication of lasers

light-emitting diodes

and single or multiple channelde filters

and so on.On the other hand

optical response of nomal-mode coupling semiconductor microcavities have attracted special interests for researchers.Opticalm icrocavities can confine light to small volumes by resonant recirculation.Devices based on optical microcavities are already indispensable for a wide range of applications and studies such as light-emitting diodes with high-efficiency and good-quality

optical switches

logic gates

lasers

photolum inescence devices

photonic crystal waveguides and so on.We investigate the normal-mode coupling dispersive medium in a symmetric 1D PCs.We use oscillator model to simulate the linear susceptibility of the dispersive layer.Given a reduced oscillator HWHM linewidth and a reduced frequency of the oscillator resonance

the single longitudinal defect mode will be split into two transmission peaks due to a high dispersive absorption.It is found that the separation between the two transmission peaks enlarges with increasing the idmensionless coupling strength.That means we can modulate the frequency shift of the dispersive defect by adjusting the parameter of the dispersive medium.We have also calculated the relationship between NMC and the oscillator

detuning effect of the cavity.By introducing a concept of complex effective refractive index

we calculated the imaginary part of the complex effective refractive index.So we can give a clear physical picture on normal coupled modes in a symmetric one-dimensional photonic crystal.