Nonlinear optics is one of the most important and active research areas nowadays in optics and photonics sciences. The multiple nonlinear phenomena generated with laser sources make this research area very attractive. For example, in a nonlinear optical medium, light can control itself during its propagation, or generate different, “new”, photons and make possible the implementation of different kind of experiments. During recent years, most of efforts in this research area have been devoted to the creation of all-optical logical devices, for the ultimate goal of designing an all-optical computer. In principle, this computer would be much faster and would have greater capability than its current electronic counterpart. Thus, the study of light propagation or different new nonlinear materials makes this area a very strategic one in information sciences. The ability of controlling how information can be stored and managed in a particular device or network is an important subject of study where, we believe, nonlinear optics has a lot to say. This research area is directly related to photonic crystals, which are artificial materials presenting optical band-gaps making possible the control of light flow in a similar way as semiconductors for electrons. The periodicity of these crystals (in the scale of the wavelength) can be simply designed and fabricated in one, two, or three spatial dimensions. These artificial structures are very important because they allow linear and nonlinear control of light in the direction of periodicity. All these studies would give us many tools for controlling light in different scenarios and make more feasible the appearance of optical devices for concrete applications.
