Filter is a kind of component which is very important in communication,and the notable filter characteristics of phase-shifted fiber grating can be used as a band-stop filter in DWDM system to realize the optical signal demodulation.A lot of factors influence filter characteristics of phase-shifted fiber grating.Through analyzing phase-shifted fiber grating of coupled mode theory,and using MATLAB software to simulate,a single-wavelength,double-wavelength and multi-wavelength reflective spectrum of phase-shi...