Locking of three coupled lasers

We investigate the stability of an array of three laterally coupled semiconductor lasers. This study of the simplest system with an underlying structure that is also found in larger arrays constitutes a first step towards understanding the stability properties of large arrays. We use a composite-cavity model, where the individual lasers are described by the transverse modes of the entire composite-cavity system. Specifically, we analyze the stable locking region, where the laser array exhibits continuous wave emission for different detunings and coupling strengths between the individual lasers. We find that the optical fields in the outer lasers are out of phase with the middle laser.