Optical frequency comb generation using cascaded injection of semiconductor lasers

Area of Science:

• Photonics
• Semiconductor Lasers
• Nonlinear Dynamics

Background:

• Optical frequency combs (OFCs) are crucial for precision measurements and communications.
• Semiconductor lasers offer compact and cost-effective solutions for OFC generation.
• Controlling nonlinear dynamics in semiconductor lasers is key to achieving stable OFC output.

Purpose of the Study:

• To investigate a novel cascaded injection-locking scheme for generating optical frequency combs (OFCs) from semiconductor lasers.
• To analyze the underlying nonlinear dynamics (period-one oscillations) that lead to OFC formation.
• To achieve stable microwave signal generation with a narrow linewidth using the proposed method.

Main Methods:

• Utilizing a two-stage cascaded optical injection system with semiconductor lasers.
• Inducing period-one (P1) dynamics in the first stage via master laser injection.
• Regenerating P1 dynamics in the second stage to achieve undamped relaxation oscillations and subharmonic generation for OFC formation.

Main Results:

• Successfully generated optical frequency combs with over 15 comb lines and a bandwidth exceeding 140 GHz.
• Observed microwave comb signals upon photodetection, initially with MHz linewidths due to laser noise.
• Demonstrated stabilization of P1 dynamics and OFC signals using a cascaded injection-locking scheme.

Conclusions:

• The proposed cascaded injection-locking scheme effectively generates OFCs from semiconductor lasers.
• The method enables stable pure microwave generation with linewidths below 3 Hz and low phase noise.
• This approach offers a promising pathway for robust and high-performance microwave photonic systems.