Fabrication-Tolerant Higher Order Laterally-Coupled Distributed Feedback Lasers

To avoid the commonly required regrowth steps in conventional distributed feedback laser fabrication, laterally-coupled distributed feedback (LC-DFB) lasers lithographically pattern the grating out of the ridge waveguide. Using higher order gratings increases the lithographic tolerances, resulting in lasers that are more amenable to mass-manufacturing techniques, such as stepper lithography. We have extended the modified coupled-mode theory to a two-dimensional cross-section, and thereby identified grating geometries that are both fabrication-tolerant and provide high performance.