Spontaneous soliton mode-locking of a microcomb assisted by Raman scattering.

Area of Science:

• Nonlinear optics
• Quantum optics
• Photonics

Background:

• Microresonator frequency combs are crucial for applications like spectroscopy and optical communications.
• Controlling the complex dynamics between different nonlinear processes within microresonators remains a challenge.

Purpose of the Study:

• To investigate and control the interplay between optical parametric oscillation (OPO) and stimulated Raman scattering (SRS) in microresonators.
• To achieve distinct frequency comb states, including self-locked Raman solitons and novel anti-Stokes combs.

Main Methods:

• Utilizing a microresonator to couple OPO and SRS.
• Employing adiabatic pump frequency detuning for deterministic soliton generation.
• Analyzing radiofrequency (RF) beat notes to characterize comb states and linewidths.

Main Results:

• Demonstrated a Raman comb with a sech2 envelope and broad RF beat note linewidth (hundreds of kHz).
• Achieved self-locked Raman single-solitons with a narrow RF beat note (25 Hz) deterministically.
• Identified a frequency comb with a Lorentzian × sech2 envelope generated via an anti-Stokes process.

Conclusions:

• Successful control over OPO-SRS interaction dynamics in microresonators is achieved.
• Deterministic generation of self-locked Raman solitons is possible without external locking.
• Novel frequency comb states, including anti-Stokes combs, can be generated by manipulating nonlinear processes.