The College of Education for Pure Sciences, Department of Physics, discussed a doctoral thesis on a theoretical study of generating optical frequency combs in micro-resonators. The thesis, presented by researcher (Hawra Abdul Hassan Mazban), included a study on optical frequency combs (OFC) and soliton generation in micro-resonators, their time evolution, and their spectral properties. Two models of equations are used to describe the OFC and soliton in microresonators, i.e. the Lugiato-Lefever equation (LLE) and the master equation (master equation). Both equations were solved numerically using two methods, the split-step Fourier method (SSFM) to solve the LLE equation, and the modified hybrid method that combines SSFM and the finite difference method to solve the master equation. The effect of several types of pulse shapes, Gaussian, super-Gaussian, and chirp pulse, was studied. It was shown that the OFC microresonator output and the resulting soliton waves depend on the pulse shape, and several OFC and soliton shape scenarios can be generated. The study also examined the effect of noise on the microresonator dynamics. Since noise cannot be eliminated in optical cavities, the study showed that noise greatly affected the dynamics of the microresonator, OFC, and the generated soliton. The effects of Temperature differences, the results showed that the refractive index of the microresonator changes, and thus the optical properties of the microresonator change.
