STABILITY AND DYNAMIC PROPERTIES OF MULTIELECTRODE LASER-DIODES USINGA GREEN-FUNCTION APPROACH

In DFB lasers the shape of the longitudinal intensity and carrier dens ity distributions changes above threshold as a result of spatial holeb urning. The longitudinally distributed coupling of spontaneous emissio n into the lasing mode also plays an important role for the noise prop erties. In this paper we demonstrate how both effects can be included in a dynamic analysis and extend our previously developed theory for m ultielectrode lasers to enable calculation of stability properties as well as small-signal modulation responses and noise spectra. The theor y is used to study global and local stability of the stationary soluti ons (modes), and numerical results for several laser structures are pr esented. We show that symmetric DFB lasers are likely to exhibit pitch fork bifurcations in their static tuning characteristics as the curren t is increased, and we discuss how the presence or proximity of such i nstabilities can affect the modulation and noise properties, in partic ular the spectral linewidth. As a result of the semianalytic treatment we also obtain the local modulation responses for a given device, whi ch show how the intensity and frequency modulation is composed along t he cavity. These local responses are very useful for optimizing the FM response of multielectrode DFB lasers.