Impact of apodisation functions on group delay and reflectivity ripple of chirped fiber Bragg gratings

Apodisation technology is introduced to optimize fiber Bragg grating based on the analysis of reflectivity spectrum and group delay response of fiber Bragg gratings. The characteristics of Hamming, Gauss and super-Gauss functions are discussed and the optimization effects of the three apodisation functions on ripple smoothness of reflectivity spectrum, group delay and linear degree are compared respectively. As a result, the optimization effects of Hamming function is better than other two functions. When the bandwidth is less than 1dB, Super-Gauss function is the best choice and proper parameters (G and m) of super-Gauss function can be selected expediently for wider bandwidth and better ripple smoothness of reflectivity spectrum.