Low-noise 750  MHz spaced ytterbium fiber frequency combs

Area of Science:

• Quantum Optics
• Laser Physics
• Frequency Metrology

Background:

• Fiber frequency combs are crucial for precision measurement.
• Stabilizing high repetition rate combs is challenging.
• Previous work lacked tight phase-locking at 750 MHz.

Purpose of the Study:

• To demonstrate two low-noise 750 MHz ytterbium fiber frequency combs.
• To achieve tight phase-locking of these combs to a continuous-wave laser.
• To establish a new benchmark for fiber comb performance.

Main Methods:

• Independent stabilization of two 750 MHz ytterbium fiber frequency combs.
• Utilizing bulk electro-optic modulators and piezo-electric transducers as fast actuators.
• Locking cavity length to heterodyne beat notes for stabilization.

Main Results:

• Achieved in-loop fractional frequency instabilities of approximately 10^-18 at 1 second.
• Demonstrated tight phase-locking with <1 rad root mean square phase noise (0.1 Hz to 10 MHz).
• Successfully stabilized two independent 750 MHz fiber frequency combs.

Conclusions:

• This work presents the first tightly phase-locked fiber frequency combs at a 750 MHz repetition rate.
• The demonstrated combs offer high stability and low noise performance.
• This advancement has implications for optical clocks and precision spectroscopy.