Non degenerate relaxation frequencies in VCSELs: proposal of a new theoretical model

Summary form only given. Optical-spectra of semiconductor lasers contain side bands symmetrically located on each side of the laser line. It corresponds to the relaxation oscillations (RO) of the carriers (1-7 GHz). We have recently shown that these RO are non degenerate and this non degeneracy results in asymmetric side bands of the laser line. This observation of two relaxation frequencies in VCSELs is not unexpected. It is just the same observation as for ROs in class-B multimode lasers. It is well known that these lasers (more precisely soli-state lasers operating with a few modes) have a set of ROs frequencies. The basic model used to describe the dynamics of VCSEL is called spin-flip model (SFM). The SFM model leads to two relaxation processes which are accompanied by damped oscillations of the laser field when laser parameters are disturbed. One is related with the total carrier number and the total photon number inside the cavity. We have modified the SFM model to get agreement with experimental results. We have first introduced the nonlinear-wave coupling on the basis of comparison with other models of laser physics.