Parity-time symmetry in monolithically integrated graphene-assisted microresonators

Area of Science:

• Photonics
• Materials Science
• Quantum Optics

Background:

• Parity-time (PT) symmetry in optical systems offers unique properties but often requires complex setups.
• Existing PT-symmetric systems typically rely on separate photonic devices or active semiconductor materials.

Purpose of the Study:

• To investigate PT symmetry and exceptional points (EPs) in a monolithically integrated system.
• To explore the potential for tunable nonreciprocal light transmission using graphene-assisted microresonators.

Main Methods:

• Utilizing the Raman effect and graphene cladding to introduce balanced gain and loss.
• Investigating PT-symmetry breaking and EPs by varying pump power and chemical potential.
• Theoretically demonstrating tunable nonreciprocal light transmission with gain saturation nonlinearity.

Main Results:

• Achieved PT-symmetry breaking and EPs in graphene-assisted coupled microresonators.
• Observed suppression and revival of intracavity field intensities with increasing graphene loss.
• Demonstrated tunable nonreciprocal light transmission with a maximum isolation ratio of 26 dB.

Conclusions:

• The proposed monolithically integrated, CMOS-compatible scheme enables microscale light field manipulation.
• This approach offers promising applications in optical communication, computing, and sensing.
• Graphene-assisted PT-symmetric microresonators provide a novel platform for advanced photonic functionalities.