Frequency combs induced by phase turbulence.

Area of Science:

• Photonics
• Nonlinear optics
• Laser physics

Background:

• Wave instability drives turbulence in hydrodynamics and leads to optical frequency combs in photonics.
• Optical frequency combs are periodic light waveforms generated through nonlinear interactions and coherent locking mechanisms.
• In microresonator combs, instability arises from resonator dispersion and Kerr nonlinearity, unlike ring lasers where it typically requires extreme pumping.

Purpose of the Study:

• To demonstrate that semiconductor ring lasers can achieve frequency comb regimes at low pumping levels.
• To investigate the role of phase turbulence in enabling frequency combs in semiconductor ring lasers.
• To connect the behavior of semiconductor ring lasers with microresonator frequency combs.

Main Methods:

• Utilizing semiconductor ring lasers with ultrafast gain recovery.
• Investigating phase turbulence as the underlying instability mechanism.
• Applying the Ginzburg-Landau formalism to formulate instability conditions.

Main Results:

• Semiconductor ring lasers exhibit frequency comb regimes at low pumping levels, contrary to previous assumptions.
• Phase turbulence, arising from phase-amplitude coupling via linewidth enhancement, drives the instability.
• Observed localized structures share properties with dissipative Kerr solitons.

Conclusions:

• Semiconductor ring lasers can generate optical frequency combs under non-extreme conditions through phase turbulence.
• This work establishes a link between semiconductor ring lasers and microresonator frequency combs.
• The findings open new avenues for exploring frequency comb generation in semiconductor devices.