Specialty Optical Fibers Handbook

normal to the layers may be described using a one-dimensional (1D) model. The

symmetry is lower in anisotropic planar chiral structures such as cholesteric

liquid crystals (CLCs) and in periodic isotropic fibers such as fiber Bragg

gratings (FBGs). Chiral short-period fiber gratings are obtained by lowering

the symmetry in either of these structures; they lack the transverse translation

symmetry of CLCs and the axial rotation symmetry of FBGs.

12.3.3 Comparison of 1D Chiral to 1D Isotropic

Layered Structures

In the simplest periodic dielectric structure, composed of alternating layers

with different refractive indices, orthogonal modes in different polarization states

propagating normal to the structure are degenerate and polarization is maintained ...