Abstract: The thesis covers various aspects on modeling semiconductor ring lasers, focusing on their nonlinear dynamics, modal properties and dynamic stability. Firstly, the noise properties have been modeled and simulated via a rate equations models. With these models the application of semiconductor ring lasers to the measurement of inertial rotation and the effect of spontaneous emission noise in the dynamics has been studied. Secondly, a traveling wave model has been developed. Also the computational tools have been created to find their stationary solutions and stability. With this model, multimode dynamics and wavelength multistability have been investigated in ring lasers. The results show that the wavelength of emission of these lasers can be selected by injection of an external field. Also, the modal properties of real devices consisting of a ring cavity and coupled waveguides for the injection and extraction of light have been investigated. The results show that the impact of the composite cavity is noticeable in the cold cavity modes and the behavior of these lasers.