Spectral and spatial dynamics in InGaN blue-violet lasers

An angular differential analysis of the longitudinal modes associated with successive spectral substructures in InGaN lasers demonstrates a large increase in the mode widths towards the red side of the spectra because of the antiguiding lens effects occurring in such gain-guided lasers. A simple model predicts the growing asymmetrical triangular-shape spectral envelope with much higher powers in the red substructures with increasing excitation, in agreement with the high-resolution spectral measurements. Moreover, the observed 20% mode-width variations imply a critical stripe-width limitation of the active medium that would prevent oscillation of higher-order modes on the blue side of the laser spectrum.