  An analytic solution for Bragg grating with linear chirp in the form of
confluent hypergeometric functions is analyzed in the asymptotic limit of long
grating. Simple formulas for reflection coefficient and group delay are
derived. The simplification makes it possible to analyze irregularities of the
curves and suggest the ways of their suppression. It is shown that the increase
in chirp at fixed other parameters decreases the oscillations in the group
delay, but gains the oscillations in the reflection spectrum. The conclusions
are in agreement with numerical calculations.
