Fig. 3: Design and microscope image of the inverse taper.

a Illustration of the inverse taper used to minimize reflections at the output facet. b Finite Element Mode (FEM) simulation of the fundamental transverse electric (TE) mode of the inverse taper with 2000 nm height (H) × 200 nm width (W). c Scanning electron microscope (SEM) image of a high-aspect-ratio inverse taper structure similar to the one used in our mid-infrared (mid-IR) laser.