Photonic crystals (PC) are materials that have spatial periodicity of their dielectric permittivity. Under certain conditions, photonic band gaps, that is, spectral regions for which propagation of electromagnetic radiation through a crystal is impossible, can be created in photonic crystals. For photonic crystals, the lattice constant should be in the range 100 nm-l µm. This range of sizes in photonic crystals can be achieved using both conventional artificial nanofabrication methods and self-assembly methods observed in objects of animate and inanimate nature. One of the most interesting properties of photonic crystals is the appearance of localized modes, which can occur in the photonic band gap when a defect is introduced into the ideal PC. In such photonic crystals, photons with states within the photonic band gap can not propagate through the PC, but they can localize in the vicinity of the defect region.