Gain-coupled DFB lasers versus index-coupled and phase shifted DFB lasers: a comparison based on spatial hole burning corrected yield

Abstract

A statistical yield analysis is presented for gain- and index-coupled DFB laser structures, allowing a comparison of their single longitudinal mode (SLM) yield capabilities. For the yield calculations, we take into account the threshold gain difference DELTA-gL and the longitudional spatial hole burning (SHB). By comparing the experimental and theoretical yield of index-coupled DFB lasers, the significance of spatial hole burning for correct yield predictions is illustrated. For the purpose of comparison, yield calculations for various lambda/4-shifted DFB lasers (with low facet reflectivities) are presented in a novel way. The most emphasis, however, is on partly gain-coupled DFB lasers. First, estimations of practical k(gain) (gain coupling coefficient) values for gain and for loss gratings are discussed. Then, for low facet reflectivities, the spatial hole burning corrected yield for various k(gain) and k(index) (index-coupling coefficient) combinations is given. Results for cleaved facets are also presented. In both cases, a large increase of the spatial hole burning corrected yield has been found. For all structures, design criteria for the optimization of the spatial hole burning corrected yield are discussed