Page 349 - Fiber Bragg Gratings

326 Chapter 7 Chirped Fiber Bragg Gratings

Figure 7.10: Reflection and delay spectrum of an unapodized 100-mm-long
grating with a chirped bandwidth of 0.75 nm. The reflection spectrum remains
unchanged when measured from either end (A). The group delays (B and C)
have been computed for light launched in the direction shown, from the short-
wavelength end (B) and the long-wavelength end (C). The net dispersion, which
is the sum of the two, is shown as curve D. This residual dispersion prevents full
recompression of a pulse dispersed by the grating.

Figure 7.11: Apodization profile of the half-cosine long wavelength-edge
apodized chirped grating is shown on above the figure in (a). Measured and
computed group delay (b), when measured in both directions.