Origin of group delay ripple in chirped fiber Bragg gratings and its effective reduction method

In this paper, the characteristics of a fiber Bragg grating fabricated with a chirped phase mask are compared with those of a fiber Bragg grating that is made chirped by addition of distortion to a uniform fiber Bragg grating without phase error. It is found that the dominant cause of generation of group delay ripples lies in the phase error of the chirped phase mask. It is demonstrated that a chirped fiber Bragg grating with smaller group delay ripples than the conventional ones can easily be obtained by adding linear distortions made of insertion of a rod containing a fiber Bragg grating without phase error into an S-shaped groove. (C) 2003 Wiley Periodicals, Inc.