PROPAGATION EQUATION BASED THEORY OF INTERMODAL INJECTION LOCKING IN SEMICONDUCTOR-LASERS

Intermodal injection locking is analyzed theoretically through the use of propagation equations inside the amplifying semi-conductor medium and the boundary conditions on the laser facets. In particular, the stability analysis is performed by considering the oscillation threshold of sideband waves generated inside the laser via intra-cavity nearly degenerate four-wave mixing processes. This study of injection locking is performed by taking into account the dispersior relationship of both the optical gain and linewidth enhancement factor. As a consequence, in intermodal injection locking, the injected-locked power is shown to be, in certain cases, lower than that of the free-running laser, and the frequency zones of stable injection locking broader than those obtained in the intramodal injection-locking case usually considered. This result could have consequences on the use of the injection-locking technique in practical devices by slackening the frequency stability constraint of the semiconductor lasers.