Nonlinear dynamics of soliton molecules in a Kerr microring

The optical Kerr microring provides an ideal platform for the study of dissipative optical solitons. The dissipative solitons are local waves generated after achieving a delicate balance between dispersion and nonlinearity, gain and loss. The dissipative bright solitons are susceptible to external noise, while the dissipative dark solitons have a higher robustness against noise and losses. In this paper, the input pump light field is split into transverse electric (TE) and transverse magnetic (TM) modes. TE mode generates bright solitons. TM mode forms dark solitons via cross-phase modulation, inducing a self-focusing effect. The bright and dark solitons bind into a soliton molecule pair through mutual interactions. We scan the entire detuning interval; within the positive small detuning interval, two modes simultaneously generate light-dark soliton pair Turing roll states. Within the larger detuning interval, the excited Brillouin scattering noise induces a high suppression ratio between the dark and bright soliton pumps, which is unfavorable for the formation of the bright-dark soliton pair. The system provides a new multisoliton manipulation scheme for optical communications. The soliton molecule pairs hold significant implications for high-precision measurement and all-optical controlling fields.