Ultra-low noise optical injection locking amplifier with AOM-based coherent detection scheme

Area of Science:

• Physics
• Optical Engineering
• Metrology

Background:

• Optical frequency transfer is crucial for applications like distributed atomic clocks.
• Existing methods face challenges with signal degradation over long fiber optic links.
• High-gain, stable amplification is needed to maintain frequency accuracy.

Purpose of the Study:

• To demonstrate a novel optical injection locking amplifier for enhanced optical frequency transfer.
• To achieve high gain and long-term frequency stability for precise frequency distribution.
• To validate the amplifier's performance in a realistic long-haul fiber link scenario.

Main Methods:

• Utilizing an acousto-optic modulator for phase modulation and a coherent detection scheme.
• Employing injection locking of a distributed feedback diode laser to an optical signal.
• Testing the amplifier in a 180 km fiber link for remote frequency transfer.

Main Results:

• Achieved approximately 59 dB gain with input carrier frequency fractional stability of 10^-20 at 1000 s.
• Successfully transferred a narrow-linewidth laser frequency to a remote site with a single amplification step.
• Demonstrated a transferred frequency stability of 10^-20 at 20000 s at the remote end.

Conclusions:

• The developed optical injection locking amplifier is effective for high-fidelity optical frequency transfer.
• The system's stability and gain performance meet requirements for optical frequency distribution and remote atomic clock comparisons.
• This technology advances the capabilities for precise metrology over extended distances.