Understanding the intracavity field dynamics in passive microresonator systems has already been intriguing. It becomes fascinating when the system is complex, such as a concentric dual microring resonator that exhibits avoided mode crossing (AMC). In this work, we present a systematic study of intracavity oscillatory field dynamics near AMC in a concentric silicon-nitride microring resonator with the help of coupled Lugiato-Lefever equation. We identify two regions where the hybrid modes are strongly coupled and weakly coupled based on their eigenfrequency separation, which originate from mode coupling near AMC. We calculate the overlap integral to identify the cutoff pump wavelength region to observe the existence of the two hybrid modes. In a strongly coupled hybrid mode region, we observe intracavity power oscillation and transfer of energy between the two hybrid modes in a periodic manner. We also evaluate the nonidentical phase variation of these two modes. In a weakly coupled hybrid mode region, power oscillation and energy transfer between modes reduces significantly, whereas their phases vary in almost identical fashion. We validate our numerical findings with the semianalytical variational method, leading to an in-depth understanding of the mode-coupling-induced dynamics. We finally analyze the polarization properties of the field confined in the coupled system. Exploiting the Stokes parameters and Jones vector, we deduce a polarization-evolving state and a polarization-locked state in strongly coupled region and weakly coupled region, respectively.

• Received 11 November 2020
• Revised 17 July 2021
• Accepted 1 September 2021

DOI:https://doi.org/10.1103/PhysRevA.104.033514