Dual-comb modelocked lasers: semiconductor saturable absorber mirror decouples noise stabilization

Area of Science:

• Optics and Photonics
• Laser Physics
• Materials Science

Background:

• Dual-comb lasers generate two coherent, independent laser outputs.
• Stabilizing the pulse repetition rate is crucial for applications like spectroscopy.
• Existing methods face challenges in maintaining stability for both beams simultaneously.

Purpose of the Study:

• To present a novel method for stabilizing the pulse repetition rate of dual-comb lasers.
• To investigate the underlying physics governing the stabilization mechanism.
• To demonstrate the feasibility of this technique with different gain materials.

Main Methods:

• Utilizing an intracavity semiconductor saturable absorber mirror (SESAM) for passive mode-locking.
• Employing an intracavity birefringent crystal for polarization-duplexing.
• Sharing all optical components within a single linear cavity for both beams.
• Analyzing laser behavior with both semiconductor and Nd:YAG gain materials.

Main Results:

• Achieved simultaneous emission of two mode-locked beams from a single linear cavity.
• Observed that cavity length adjustments for one polarization minimally affected the other's pulse repetition rate.
• Demonstrated that pulse arrival timing jitter is decoupled by the SESAM and locked with appropriate pulse overlap.
• Confirmed noise stabilization is possible for both combs.

Conclusions:

• The presented dual-comb laser design offers effective pulse repetition rate stabilization.
• The decoupling of timing jitter by the SESAM is key to the observed stability.
• This technique is particularly promising for semiconductor lasers, enabling integrated devices like MIXSELs.