Fabrication and characteristics of gain-coupled distributed feedback semiconductor lasers with a corrugated active layer

A distributed feedback (DFB) semiconductor laser structure in which pure gain coupling can be realized is proposed. The fabrication procedure of this structure makes use of a special feature of organometallic vapor phase epitaxy. Lasers of this structure were fabricated to show the validity of the proposal. Coupling coefficients of DFB lasers were calculated considering the gain-coupling component. Using the results, a DFB laser was designed to obtain pure gain coupling. The parameters of the actual structure observed under a scanning electron microscope showed good agreement with those designed. Device characteristics predicted for purely gain-coupled DFB lasers were achieved. For greater gain coupling and lower threshold current operation, an optimization of the Al composition of the pattern-providing layer and the thickness of the active layer in the structure has been carried out