Wide tuning of silicon-on-insulator ring resonators with a liquid crystal cladding

Wide electrical tuning of silicon-on-insulator ring resonators is demonstrated using a top cladding layer of nematic liquid crystals. A tuning range of $31\mathrm{nm}$ is demonstrated for ring resonators guiding the TM mode, covering nearly the entire C-band of optical communications. Ring resonators guiding the TE mode can be tuned over $4.5\mathrm{nm}$. The combination of a liquid crystal director calculation and a fully anisotropic mode solver confirms the interpretation of these experimental results. The realization of broad and low-power tuning in silicon-on-insulator opens up new opportunities in the field of tunable lasers, filters, and detectors.