| Abstract [eng] |
In this dissertation two main topics are discussed, relevant to the development of modern, compact and widespread application spectroscopic terahertz imaging systems. Namely development of terahertz diffractive optics and variable frequency polaritonic infrared optical components is described. Development and performance of direct laser ablation fabricated multilevel phase Fresnel lenses and metal Soret zone plates for focusing of 0.6 and 4.7 THz frequency radiation are discussed in the first part of this dissertation. Characterization of fabricated components was carried out, demonstrating the applicability of the fabrication method in component development. Optimal lens design was also found and application of a fabricated component in an experimental 0.6 THz frequency imaging setup was demonstrated. Second part of this dissertation deals with the development of polaritonic components with specifically designed infrared spectral features in the infrared spectral range described by the Reststrahlen band of the semiconductor. Optical spectra modelling of heavily doped n-GaN surface relief gratings and metal grating coupled heterostructures was carried out using custom modified rigorous coupled wave analysis method. Optimal n-GaN grating height and periodicity were chosen and fabrication was carried out according to the optimal modelled parameters. Close match was demonstrated between the modelled and experimental results therefore validating the modeling and fabrication methods in developing optical components with custom frequency spectral features. Finally, it was shown that thermally excited n-GaN surface relief gratings are applicable in developing coherent, variable frequency infrared thermal sources. |
