Transportable clock laser system with an instability of 1.6 × 10^-16

Area of Science:

• Physics
• Metrology
• Optical Engineering

Background:

• Ultra-stable lasers are crucial for advanced applications like navigation and fundamental science.
• Transportable clock lasers require high stability and low sensitivity to environmental factors.

Purpose of the Study:

• To present a novel transportable ultra-stable clock laser system.
• To characterize its frequency stability and sensitivity to acceleration.

Main Methods:

• Utilized a Fabry-Perot cavity with crystalline Al_0.92Ga_0.08As/GaAs mirror coatings and fused silica substrates.
• Employed a 20 cm-long ultra-low expansion (ULE) glass spacer.
• Mounted the cylindrical cavity at 10 points to minimize vibrations.

Main Results:

• Achieved a fractional frequency instability down to 1.6 × 10^-16.
• Measured acceleration sensitivities of 2(1)×10^-12 /(ms^-2), 3(3)×10^-12 /(ms^-2), and 3(1)×10^-12 /(ms^-2) for Cartesian directions.
• Predicted thermal noise floor of σ_y = 7 × 10^-17 at one second averaging time.

Conclusions:

• The developed laser system demonstrates state-of-the-art performance for transportable clocks.
• Its low acceleration sensitivity makes it robust for field deployment.
• The system represents a significant advancement in portable high-precision timekeeping technology.