Coherent suppression of backscattering in optical microresonators.

Area of Science:

• Photonics
• Optical Engineering
• Materials Science

Background:

• Light propagation in waveguides can lead to backscattering from Rayleigh scatterers.
• In high-quality-factor whispering-gallery-mode microresonators, backscattering originates from surface or bulk imperfections.
• Minimizing backscattering is crucial for many microresonator applications.

Purpose of the Study:

• To demonstrate a method for coherently suppressing backscattering in microresonators.
• To investigate the use of an external scatterer to control backscattering.
• To improve the performance of microresonator-based devices limited by back reflections.

Main Methods:

• Introducing an additional scatterer into the near field of a microresonator.
• Precisely controlling the position of the external scatterer.
• Utilizing destructive interference between intrinsic and induced backpropagating fields.

Main Results:

• Achieved over 30 dB suppression of backscattering in high-quality-factor microresonators.
• Demonstrated coherent control over light backpropagation.
• Validated the effectiveness of the destructive interference technique.

Conclusions:

• External scatterer-induced destructive interference offers a powerful method to suppress microresonator backscattering.
• This technique can enhance the performance of devices like ring-laser gyroscopes and dual frequency combs.
• The findings are relevant for integrated photonic circuits, improving laser stability and component performance.