Spectral width reduction in multilongitudinal mode lasers by spatial loss profiling

Spatial loss profiling is experimentally and theoretically explored as a means of creating technologically useful reductions in the spectral width of multilongitudinal mode lasers. Lossy regions have been introduced at controlled locations along the optical axis of commercial laser diodes for the purpose of reducing the intensity of undesired longitudinal modes. Operation approaching single-mode characteristics with side-mode suppression better than 20 dB was experimentally achieved at 1.5X threshold current by the addition of three lossy regions. A rate equation model describes the effectiveness of spatial loss profiling to obtain quasi-single-mode operation and is used to explore its effects upon laser dynamics.>