A novel ring resonator with series coupled double-ring

Abstract

A novel filter with dual micro-ring in series is theoretically investigated basing on the coupled modes and transfer matrix method in this article. A combiner is added to connect the output of through port and drop port in contrast to conventional structure. Under an ideal condition, the transmission spectrum intensity is worked out by employing transfer matrix method and the final output spectrum is analyzed by the simulation of Matlab. In addition, the effects of the coupling coefficient and other parameters are discussed in detail. The simulation results show that when the coupling coefficient of two micro rings is equivalent to straight waveguide counterpart, the output spectrum appears pseudo-norm and a periodic output spectrum phenomenon any way; In contrast, when the coupling coefficient of dual micro-ring and straight waveguide are different, we can find the free spectral range becomes 3 ,4 times higher than the single micro-ring model structure as dual micro-ring radius is 297.6μm, 396.8μm, respectively. Furthermore, the pseudo-norm is small enough to be neglected. Then, the perfect extinction ratio and the extraordinary narrow bandwidth with quality factor of 10⁵ are maintained. In comparison of conventional dual micro-ring filter, the pseudo-norm in this article is much better restrained and the property of micro-ring resonator achieves a distinct-obvious progress as a result. The proposed filter greatly enhances the free spectral range and has broad prospect of application.