ABSTRACT
Photonic crystals have been the subject of intensive studies over the last 15 years, since the pioneering work of Yablonovich. They present a wide band gap, which is almost independent of the incidence angle and, thus, enable light confinement in one, two or three directions. A structure characterized by a one-dimensional periodicity has been well known for quite a long time. And indeed, such are the multilayered dielectric mirrors, used in many domains of physics and optical engineering. Gratings play a key role in chirped pulse amplification. The first attempts used the positive group velocity dispersion of a single-mode fiber to temporarily stretch the ultrashort pulse. Light confinement and guiding in a single dimension is ensured by using planar waveguides. Channel waveguides and optical fibers confine light in two dimensions, but they suffer of two important limitations: dispersion and bending losses.
