Experimental observation of localized luminescence clamping in complex-coupled DFB laser diodes

The longitudinal dependence of the standing wave in a complex-coupled DFB laser is experimentally investigated. We have observed localized clamping of the luminescence for unstable operation conditions such as multi-mode emission. We present measurements of the variation in luminescence as a function of position along the laser cavity length for various relative phases between facets and grating. We impose these conditions by systematically depositing layers of Ge to change the relative facet-to-grating distance in an InGaAsP MQW complex coupled DFB laser. A model based on standing-wave considerations is used to explain the experimental findings.