Characterization of losses in InAlGaN bent waveguides

The goal of this work lies in expanding the integrated circuit technology to short wavelengths with the use of nitride emitters. We propose an approach that allows monolithic fabrication of lasers and waveguides using the same epitaxial structure. This is achieved by increasing the misorientation of the substrate locally, prior to the epitaxy, which allows local modification of the indium incorporation into the InGaN layers. Such areas are then used for etching down waveguides with low absorption. Within this work, we develop our technology for the fabrication of waveguide combiners, which involves creating waveguides with bends that bring two or more optical modes into close proximity. We compare systems consisting of 1 mm long laser diodes coupled to 1 mm bent waveguides with bend angles from 2.5° to 45° and different bend radiuses. We estimate the losses based on the optoelectrical parameters of the working system, treating it as a laser diode with a passive region introducing optical losses.