EXCESS-NOISE FACTOR IN PARTLY GAIN-COUPLED DFB LASERS

We study the effect of complex coupling coefficient on the excess-noise factor in partly gain coupled DFB lasers. It is shown that for a weak and moderate coupling region, the phase of the coupling coefficient affects remarkably the noise level in the laser structure. Moreover, for pure gain coupling structure (phi = pi/2) or for structures in which gain coupling dominates (phi lies in the vicinity of pi/2) we observe an interesting behavior of the characteristics. In contradiction to the characteristics for other phases, a local maximum of the excess-noise factor occurs for some certain value of the coupling strength.