Mechanisms of optical confinement in phase-locked laser arrays

The nature of optical confinement in phase-locked laser arrays (PLLAs) with a mesa-stripe structure (MSS) has been studied. Two main mechanisms are distinguished, which are based on the variation of the waveguide effective refractive index due to MSS formation and on the refractive index modulation induced by the heating of the structure. Stable operation was achieved when either weak or strong optical coupling was realized in the PLLA. A phase-locked regime of radiation was obtained only for laser diodes with strong optical coupling. In the latter case the angle divergency was not greater than 2 degrees for the antisymmetric supermode emission from the PLLA.