Research of fiber Bragg gratings with chirped refractive index modulation

The detailed corresponding relationship of chirped refractive index modulation coefficient, initial refractive index modulation and grating periods chirp coefficient were deduced by using coupled-mode theory, and both the numerical simulation investigation and experimental results were also given. The conclusions are drawn as follows: the equivalent grating periods chirp coefficient is determined by both the chirped refractive index modulation coefficient c and initial reactive index modulation δ̄n eff. Both the equivalent grating periods chirp coefficient and grating periods chirp coefficient c p act together to determine the dispersion compensation amount. By properly controlling the average refractive index modulation, we can fabricate different dispersion compensation amount fiber Bragg gratings by using the same phase mask.