Optical loss in bent-waveguide superluminescent diodes

Abstract

The optical loss in the bent region is one of the key features for bent-waveguide superluminescent diodes which affects the device performance greatly under some conditions. In our work, this bend loss is investigated with different waveguide structural parameters such as the ridge width, etching depth and curvature radius. It is found that the bend loss is sensitive to the etching depth of the ridge. Significant loss will occur in a shallow and excessively wide or narrow ridge waveguide, and the waveguide with a small curvature radius can also enhance the loss. Effects of the loss on the device properties such as power and emission spectrum have also been investigated by using a quantum-dot device model. It is observed that as the bend loss increases, intersections will appear on the power–current curves obtained from both ends of the device, and this phenomenon is further studied with different cavity lengths and bend losses.