METAL-GRATING-OUTCOUPLED SURFACE-EMITTING DISTRIBUTED-FEEDBACK DIODE LASERS

The theoretical analysis of antiphase, surface‐emitting, complex‐coupled, distributed feedback (SE‐CC‐DFB) lasers is presented. The specific configuration chosen for analysis is relatively simple: a metallic second order grating placed atop a diode‐laser structure. This type of SE‐CC‐DFB structure can be fabricated by a lift‐off and evaporation process; can operate in a single‐lobed, orthonormal beam with a rather uniform near‐field intensity pattern, and external differential quantum efficiency, ηd, values in excess of 30%. The dependence of the gain threshold on grating duty cycle for both the symmetric and antisymmetric (longitudinal) modes is presented and discussed. The external differential quantum efficiency for the symmetric mode is found to steadily increase with grating length at the expense of the degree of near‐field‐pattern uniformity.