Unifying Frequency Combs in Active and Passive Cavities: Temporal Solitons in Externally Driven Ring Lasers

Area of Science:

• Optics and Photonics
• Nonlinear Dynamics

Background:

• Frequency combs are crucial in optics, with chip-scale sources like semiconductor lasers and microresonators being key research areas.
• Active (lasers) and passive (microresonators) cavities have historically been studied separately.
• Integrated photonics seeks compact and efficient light sources.

Purpose of the Study:

• To propose a formal unification of active and passive chip-scale frequency comb cavities.
• To introduce a general theoretical framework applicable to both cavity types.
• To investigate the physics of hybrid devices, specifically semiconductor ring lasers with external optical drives.

Main Methods:

• Development of a general equation describing both active and passive optical cavities.
• Theoretical analysis of a hybrid semiconductor ring laser system.
• Investigation of symmetry breaking and self-localization phenomena in dissipative systems.

Main Results:

• A unified theoretical framework for chip-scale frequency comb cavities.
• Demonstration of temporal soliton existence in a hybrid semiconductor laser system.
• Identification of phenomena responsible for soliton formation, linking microresonator and semiconductor laser physics.

Conclusions:

• The proposed general equation successfully unifies diverse frequency comb cavity types.
• Hybrid semiconductor lasers can host temporal solitons, previously observed mainly in microresonators.
• This work bridges the understanding between different integrated comb technologies and dissipative systems.