Fig. 3
Experimental demonstration of suppressed reflection and improved quality factor in MRRs by engineering geometry of the Mie scatterer. a Transmission (T1→3) and (b) reflection spectra (R1→4) of the MRR in add-drop configuration as shown in Fig. 1 for a Mie scatterer with D = 100 nm and W = 80 nm, 160 nm, 200 nm, 240 nm, and 320 nm (top to bottom). The devices with different \(W\) are fabricated in the same run to make sure that they are affected in the same way during the fabrication (e.g., similar fabrication imperfections and sidewall roughness). R1→4 becomes zero, suggesting the emergence of an EP, at W = 200 nm in good agreement with the design process in Fig. 2. c Infrared camera captured top view of a ring resonator without and (d) with the Mie scatterer (W = 200 nm, D = 100 nm). A single mode fiber launches light through the grating coupler connected to port 1. The ring resonator without the Mie scatterer experiences intermodal scattering due to sidewall roughness which results in strong reflection signal at port 4 (reflection port), which is suppressed in d. e T1→3 and (f) R1→4 of the MRRs shown in the c (black) and d (blue), respectively. Dots: experimental data. Curves: CMT fits