Fig. 1. SEM image of one of the resonators.

Fig. 2. Setup used for small spot direct UV writing in trimming experiments.

Fig. 3. Schematic of the device and the writing procedure.

Fig. 4. Transmission spectra of fabricated racetrack resonators for different lengths of the exposed section of the resonator. (a) Device without oxide cladding and (b) device with oxide cladding.

Fig. 5. Dependence of the resonant wavelength shift on the number of lines written across the racetrack. For each line, an arc length of approximately 14 μm has been exposed. (a) Device without oxide cladding and (b) device with oxide cladding.

Fig. 6. (a) Transmission spectra of the simulated device, compared to the measured spectrum. (b) Transmission spectra obtained by simulation, before and after changing the refractive index of silicon nitride.

Fig. 7. Measured resonant wavelength shift as a function of change in the ambient temperature. (a) Device without oxide cladding and (b) device with top oxide cladding.