Highly efficient tunable optical filter based on liquid crystal micro-ring resonator with large free spectral range

Abstract

A highly efficient tunable optical filter of liquid crystal (LC) optical micro-ring resonator (MRR) was proposed. The 4-μm-radius ring consists of a silicon-on-insulator (SOI) asymmetric bent slot waveguide with a LC cladding. The geometry of the slot waveguide resulted in the strong electro-optic effect of the LC, and therefore induced an increase in effective refractive index by 0.0720 for the quasi-TE mode light in the slot-waveguide. The ultra-wide tuning range (56.0 nm) and large free spectral range (FSR) (~28.0 nm) of the optical filters enabled wavelength reconfigurable multiplexing devices with a drive voltage of only 5 V. The influences of parameters, such as the slot width, total width of Si rails and slot shift on the device’s performance, were analyzed and the optimal design was given. Moreover, the influence of fabrication tolerances and the loss of device were both investigated. Compared with state-of-the-art tunable MRRs, the proposed electrically tunable micro-ring resonator owns the excellent features of wider tuning ranges, larger FSRs and ultralow voltages.

Keywords

integrated optics devices / liquid crystals / micro-ring resonator / slot waveguide / wavelength tuning

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Acknowledgements

The authors would like to thank Shuchang Yao and Yong Mei for useful discussion. This work was supported by the National High Technology Research and Development Program of China (No. SS2015AA010104), the Major Project of Science and Technology Innovation Program of Hubei Province of China (No. 2014AAA006), and the National Natural Science Foundation of China (Grant No. 61107051).

RIGHTS & PERMISSIONS

2014 Higher Education Press and Springer-Verlag Berlin Heidelberg