Mode Competition Between Longitudinal and Lateral Modes in III-Nitride Broad-Ridge Laser Diodes

Abstract

Mode competition in semiconductor laser diodes typically causes a continuously repeating spectral modulation by periodic mode hopping through longitudinal modes. High-power laser diodes include a broad ridge waveguide that supports multiple lateral mode operation, interacting with the dynamically changing spatial distribution of charge carriers. We investigate the time-dependent behavior of longitudinal-lateral mode competition in III-nitride-based broad-ridge laser diodes, involving several longitudinal mode combs, each corresponding to a different lateral mode. For this, we perform lateral scans of streak camera measurements, take single shot images, and develop a rate equation model for numerical simulation of the process. We observe mode competition that involves all active lateral modes, driven by asymmetric mode coupling. In particular, the small wavelength spacing between adjacent lateral modes and spatial lateral hole burning are influencing mode competition dynamics in broad-ridge devices. Furthermore, we investigate the role of mode clustering on the dynamical behavior and how long-time periodicity depends on the laser diode properties.