Fig. 6

Optical trimming of micro-ring resonators. a Detuning of two initially superimposed resonance dips corresponding to two micro-ring resonators with 100 μm (blue line) and 120 μm (red line) in radius connected to a common bus waveguide. The largest ring is left fixed while the smaller ring is phase-shifted via step amorphization to fully isolate the response of each ring. b Trimming of the 120 μm micro-ring to match the resonance dip of the smaller ring (fixed), thus, correcting the detuning in a but with an overall wavelength shift of 0.6 nm. The inset shows an optical microscope image of the actual device. c Demonstration of combined amorphization and crystallization to properly trim one micro-ring resonator and compensate ‘over-shifting’. Nonvolatile response is demonstrated in the last state of the device (bottom panel) which was measured 4 × 10⁶ s (i.e. 47 days) later