Nonlinear Dynamics in a Solitary Microlaser Based on the Interaction Between Decoupled Modes

Nonlinear dynamics in semiconductor lasers have been realized by external optical injection, optical feedback, optoelectronic feedback, and mutual coupling. In this article, an experimental demonstration of nonlinear dynamics in a solitary whispering-gallery mode microcavity laser is achieved based on the internal mode interaction. A natural hybrid quadrilateral mode exists in a circular-sided octagonal microcavity, which is coupled by two independent orbital modes formed by the sub-adjacent total reflection. By designing a spatially selective injection area along the field distribution of one quadrilateral mode, the hybrid quadrilateral mode is decoupled into two quadrilateral modes. The frequency offset between two decoupled modes is tuned through the non-uniform injection current. The interaction between the decoupled modes in the isolated-selectively-injected microlaser facilitates abundant nonlinear dynamics including mode locking, four-wave mixing, period-two oscillation and weak chaotic state. Our scheme provides a method for self-generated nonlinear dynamics, and paves the way for mode engineering of tailoring lasing actions in microcavity lasers.