Fig. 4: Effects of defects in an unscaled cavity DDirac = 0, NDefect = 3.
From: Topological quantum cascade laser with Dirac-scaled valley edge modes
a FESEM image with dashed colored boxes highlighting the position of the defect sites within the cavity, while the black triangular dashed lines indicate the topological interface of the unscaled waveguide. b Magnified image for a clearer view of the defect sites within the device. The color of the dashed outline around the picture indicates its respective position in part a of the figure, while the black dashed line indicates the topological boundary. c Simulated normalize E-field shows that defect is able to significantly disrupt the circulating in-plane mode within narrower waveguide causing localization within the cavity. d Experimental measurements of the device operating at 0.53 kA/cm2. Measurements made without any cover plate are plotted in black, while measured emissions from individual defect are plotted in their respective color highlighted in part a of the figure.
