Dispersion and polarization properties in photonic crystal fibers

Systematic knowledge of the particular guiding properties of photonic crystal fibers (PCF's) permits the achievement of structures with flattened, or even ultraflattened, positive, negative, or nearly-zero group velocity dispersion for different wavelength ranges. On the other hand, we have identify a PCF, called super-square PCF, in which the introduction of an off-lattice hole generates a highly anisotropic intraband guidance, and then the structure operates as a polarization maintaining fiber. Moreover, the combination of this anisotropy and intraband guidance gives rise to a radically new mechanism of polarization discrimination, which leads to a new class of single-polarization single-mode fibers. In both cases the goal is to control the dispersion and polarization properties in PCFs by modifying solely the geometrical parameters of these fibers. Keywords: fiber design, flattened dispersion.