Fig. 2: Transmission characteristics of the concentric racetrack resonator.
From: Broadband high-Q multimode silicon concentric racetrack resonators for widely tunable Raman lasers
a Microscope image of the concentric resonator with zoom-in directional coupler region in the inset. b, c Transmission spectra with wavelength ranges from 1260 to 1360 nm and from 1450 to 1650 nm. d, e Selected transmission spectra region around 1329.5 and 1480.5 nm where the inverted triangle marks the higher-order mode. f Intrinsic Q (Qi), coupling Q (Qc), and loaded Q (QL) factors of the TE0 modes at resonant wavelengths from 1260 to 1360 nm and from 1450 to 1650 nm (the absent wavelength range covering 1360–1450 nm is limited by the tunable lasers).
