Compact Narrowband Optical Filter Based on Ring Ressonators in Silicon Photonics

Abstract

In this paper, we present and discuss a new proposal for narrowband optical band pass filters based on asymmetric ring resonators in silicon. We carried out our investigation, by means of analytical and numerical calculations, to find out the best ring radii ratio and spacing between the rings in order to achieve narrow band filtering. As result, we devised a three-ring structure that performs as an 11.7 GHz optical band pass filter and, then, by cascading three structures of this, we obtained a 7.1 GHz optical band pass filter. Furthermore, this sort of filter would occupy a 20 m per 28 m area, which is considerably smaller than the correspondent state-of-the-art reported in literature until now. We also demonstrated this filter is suitable to mitigate signal-fading effects in Radio over Fiber (RoF) links. Our results indicate that, by using the proposed filters, the maximum propagation distance for RoF links could be increased from 4 km to 40 km. Since this new filter combines reduced dimensions, it has great potential to integration with other opto-electronics components into a silicon photonics circuit.