Theory and experiment of laterally coupled multi-longitudinal-mode semiconductor lasers

This report presents simulations and measurements of multimode dynamics in the twin-stripe laser resulting from complicated gain competition effects. The theory is based on a novel multi-longitudinal rate equations model, while accounting for both coherent and incoherent lateral coupling between the lasers. The experiments allowed measurements of RIN and optical power spectra for each laser separately as functions of the independently varied stripe currents and yielded sufficient data that were used to extract parameter values for the simulations. On the basis of the experimental data and the results of simulations it can be concluded that the operation predominantly takes place on several longitudinal modes in both lasers and that the lateral coupling is of a global nature, coupling between the two combs of longitudinal modes. This introduces highly complex inter and intra-stripe mode-competition effects resulting in various types of dynamics that adequately explains the complicated bifurcation structure observed in thesse devices when the current i varied.