Comment on "Design of a broadband highly dispersive pure silica photonic crystal fiber"

In a recent paper, Subbaraman et al. [Appl. Opt. 46, 3263–3268 (2007)] reported a theoretical and numerical study of highly dispersive pure silica photonic crystal fiber supporting group-velocity dispersion exceeding −2 × 104 ps=nm=km. This Comment argues that the authors consider only one of two sides of the same coin by not taking the corresponding beating length into account.