Optical coupling of two injection lasers: A new experimental approach to study the gain broadening mechanism

A new type of experiment, the optical coupling of two injection lasers, is presented. This method is used to study the gain broadening mechanism for three different types of laser structures: proton bombarded stripe geometry,
V
-groove, and channeled substrate planar stripe (CSP) lasers. The gain reduction in the presence of a strong injected light is detected with high sensitivity by a differential measurement. Independent of the laser structure, the homogeneous gain broadening mechanism is by far dominating.