Phase noise reduction by optical phase-locked loop for a coherent bichromatic laser based on the injection-locking...

Area of Science:

• Atomic, Molecular, and Optical Physics
• Laser Physics and Photonics

Background:

• Achieving low phase noise in bichromatic laser systems is crucial for high-precision measurements.
• Existing methods like optical injection have limitations in noise reduction.

Purpose of the Study:

• To present a novel coherent bichromatic laser system with significantly reduced phase noise.
• To demonstrate the effectiveness of combining optical injection with an optical phase-locked loop.

Main Methods:

• Generating coherent laser beams with a precise frequency difference (9.192 631 77 GHz) using an electro-optical modulator.
• Implementing an optical phase-locked loop (OPLL) to actively suppress phase noise.
• Independently controlling laser beam intensities and polarizations.

Main Results:

• Achieved low phase noise levels: -41, -81, -98, -83, -95 dBrad²/Hz at various offset frequencies.
• Reduced phase noise by 20-30 dB compared to optical injection alone.
• Decreased the intermodulation effect on atomic clocks by an order of magnitude.

Conclusions:

• The proposed system effectively reduces phase noise and intermodulation effects.
• Independent control of laser parameters enhances system stability.
• This technology is promising for advanced atomic coherence experiments and precision timing.