In this thesis, we obtain a comprehensive picture of the coupled dynamics of optical modes and charge carriers in AlGaInN-based laser diodes with a particular emphasis on broad-ridge laser diodes. From a theoretical standpoint, broad-ridge lasers can be considered as the more general case, where the lateral carrier dynamics, lateral modes, and their interplay with longitudinal mode dynamics are crucial aspects that need to be considered. These properties are less prominent in the case of single lateral mode operation in narrow-ridge laser diodes, thus they receive less attention. From an application standpoint, broad-ridge laser diodes are a specialized, less common variant, compared to the widely used narrow-ridge devices. However, based on a deep understanding of their static and dynamic effects and properties, we lay the foundation for further optimization towards improved performance and for the development of innovative devices providing new features and applications.