Cross-coupled parallel microring resonators and its comparison to coupled-resonator induced transparency

Abstract

We propose a new coupled waveguide optical resonator (CROW) configuration constructed with cross-coupling structure instead of the typical direct coupling. We also extend the traditional matrix formalism of CROWs to incorporate the new coupling structure. The cross-coupled CROW reveals a novel effect characterized by a main linewidth at normalized frequency φ=0, and two accompanying narrower linewidths, high Q-factor transmitted lines at normalized frequency φ=±π. This effect differs sharply from the coupled-resonator-induced transparency (CRIT) generated with the typical direct coupling-based CROW. We also compare other features of the two CROW types. Lastly, this new effect has application in two-wavelength photonic filtering.