Parity-time-symmetric coupled microring lasers operating around an exceptional point

Area of Science:

• Physics
• Optics
• Photonics

Background:

• Parity-time (PT) symmetry offers unique properties in optical systems.
• Exceptional points (EPs) are singularities in non-Hermitian systems where eigenvalues and eigenvectors coalesce.
• Microring resonators are fundamental components in integrated photonics.

Purpose of the Study:

• To investigate the behavior of PT-symmetric coupled microring systems near an exceptional point.
• To demonstrate stable single-mode lasing in spectrally multimoded microring systems.

Main Methods:

• Theoretical analysis of a parity-time-symmetric coupled microring system.
• Exploiting the abrupt phase transition occurring at an exceptional point.
• Experimental demonstration of lasing characteristics.

Main Results:

• The system exhibits distinct behavior in the vicinity of an exceptional point.
• Stable single-mode lasing is achieved in a system that would otherwise support multiple spectral modes.
• The abrupt phase transition at the EP facilitates mode selection.

Conclusions:

• Exceptional points in PT-symmetric microring systems can be leveraged for advanced optical functionalities.
• This work presents a novel method for achieving single-mode lasing in multimoded resonators.
• The findings have implications for developing stable and efficient laser sources in integrated photonic devices.