The transmission spectrum of the phase-shifted and apodized long-period fiber grating with different parameters is calculated and analyzed based on the fundamental matrix approach. This paper presents the design method of phase-shifted optimum, which uses the nonuniform phase-shifted method to optimize the transmission spectrum
of long-period fiber grating. Compared with uniform phase-shifted and apodization method, this method can effectively remove the sidelobes near the resonant wavelength. The calculation and analysis results show that it is an effective design method compared with the design method of apodization optimum.
The linear polarization sensitivity of scanning system is comparatively high or changes with the scanning angle. Due to these shortcomings of scanning system, a new design of scanning subsystem is given in this paper. It can overcome the effect of the scanning angle on the linear polarization sensitivity while keeping on the low linear polarization sensitivity.