Functional photonic crystals device designs

Devices which are applicable in many areas can be designed by using photonic crystals structures. In this thesis, numerical and experimental results of asymmetric light propagation in a different designed photonic crystal are presented. Asymmetric light propagation is achieved by changing the positions of the unit cells of photonic crystal. The amount of power collected at the output of the waveguide is different for the forward and backward propagation directions. Also another photonic crystal application which is called rainbow trapping is studied. Rainbow trapping in a newly designed two-dimensional photonic structure are investigated with numeric results. By adjusting the structure parameters, trapping of light in the structure is provided. For broadband electromagnetic wave trapping the position and dielectric filling factor of each unit cell in the structure are adjusted properly. Using completely transparent structre provides light trapping in different electromagnetic regions by the change of the effective refractive index depending on the position. In addition, a novel technique for spatial wavelength division using graded index photonic crystals is proposed. The different wavelengths follow different ways through the structure having hyperbolic secant index profile and leave the structure in different positions. Thus, light wave emanates from the graded index medium at different locations with different exit angles. This condition shows that the graded index photonic crystals can be used for the design of wavelength selective media.