Modelling multimode dynamics of semiconductor ring lasers

High frequency mode-locking of semiconductor lasers cannot be fully explained by the classic model of a saturable gain and absorber. In this project we investigate whether four-wave-mixing between counter-propagating modes in a semiconductor ring laser mediated by carrier depletion provides an ultrafast mechanism for locking of the longitudinal modes.

A modal decomposition method and a time-frequency-domain formalism for the analysis of multimode dynamics of semiconductor ring laser are developed. The diffusion coefficient is suggested as a crucial parameter to take into account. The directional switching dynamics and dependence on the operation parameters has been studied. The lasing wavelength switching accompanied by directional flipping have also been studied. In this framework, a prior selection of the lasing mode is seen as a key factor for the numerical results.