A hertz-linewidth semiconductor laser self-injection locked to a microresonator with electromagnetically induced...

Area of Science:

• Physics
• Quantum Optics
• Laser Technology

Background:

• Semiconductor lasers are crucial for modern technologies but suffer from inherent linewidth limitations.
• Existing linewidth narrowing techniques often require complex setups or lack sufficient performance.
• Optical feedback methods are promising but require strong and narrow feedback signals.

Purpose of the Study:

• To develop a method for achieving hertz-level intrinsic linewidth in semiconductor lasers.
• To investigate the use of electromagnetically induced transparency (EIT) in microresonators for enhanced optical feedback.
• To demonstrate self-injection locking for narrow linewidth chip-scale lasers.

Main Methods:

• Utilizing an all-pass microresonator exhibiting electromagnetically induced transparency (EIT) for optical feedback.
• Employing EIT resonances for stronger and narrower optical feedback compared to traditional methods.
• Integrating the microresonator with a semiconductor laser for self-injection locking.

Main Results:

• Achieved intrinsic linewidth narrowing from 157 kHz to 6.3 Hz.
• Reduced white frequency noise by over four orders of magnitude.
• Demonstrated linewidth narrowing one order of magnitude better than DFB lasers with Rayleigh-scattering feedback.

Conclusions:

• EIT-based optical feedback from microresonators offers a powerful method for extreme linewidth narrowing.
• This technique enables the creation of narrow linewidth chip-scale lasers essential for coherent optical systems.
• The method is applicable to optical communication, metrology, and sensing applications.