Dynamics of soliton self-injection locking in optical microresonators

Area of Science:

• Photonics
• Nonlinear Optics
• Integrated Photonics

Background:

• Soliton microcombs are chip-scale optical frequency combs with broad applications.
• Self-injection locking simplifies driving requirements for soliton microcombs.
• The nonlinear dynamics of laser self-injection locking to microresonators remain incompletely understood.

Purpose of the Study:

• To develop a theoretical model for laser self-injection locking to a nonlinear microresonator.
• To construct hybrid integrated soliton microcombs with electronically detectable repetition rates.
• To investigate the nonlinear dynamics of this self-injection locking process.

Main Methods:

• Developed an original theoretical model for nonlinear self-injection locking.
• Constructed hybrid integrated soliton microcombs using DFB lasers butt-coupled to silicon nitride microresonators.
• Employed a novel real-time technique to study soliton formation and repetition rate evolution.

Main Results:

• The microresonator's Kerr nonlinearity significantly alters laser diode behavior and locking dynamics, causing red-detuning.
• Observed non-trivial soliton self-injection locking features, including soliton generation during both diode current sweep directions.
• Achieved soliton microcombs with electronically detectable repetition rates of 30 GHz and 35 GHz.

Conclusions:

• The study provides crucial insights into the nonlinear dynamics of laser self-injection locking to microresonators.
• Findings offer guidelines for building electrically driven integrated microcomb devices.
• This work facilitates enhanced control over laser self-injection locking dynamics for microcomb system applications.