Realization of phase locking in good-bad-cavity active optical clock

Area of Science:

• Atomic, Molecular, and Optical Physics
• Laser Physics and Technology
• Metrology and Measurement Science

Background:

• Dual-wavelength active optical clocks (DW-AOCs) are crucial for high-precision timekeeping.
• The residual cavity-pulling effect in DW-AOCs hinders linewidth narrowing.
• Existing methods struggle to overcome limitations in achieving ultra-narrow linewidths.

Purpose of the Study:

• To experimentally achieve cavity-length stabilization for 1064/1470 nm DW-AOCs.
• To mitigate the cavity-pulling effect in dual-wavelength systems.
• To enhance the performance and stability of active optical clocks.

Main Methods:

• Utilized phase locking of two independent 1064 nm good-cavity lasers.
• Implemented cavity-length stabilization for the dual-wavelength system.
• Experimental setup focused on 1064/1470 nm laser wavelengths.

Main Results:

• Achieved frequency tracking accuracy better than 3 × 10^-16 at 1 s, reaching 1 × 10^-17 at 1000 s.
• Reduced the most probable linewidth of each 1470 nm bad-cavity laser to 53 Hz (a quarter of the previous value).
• Successfully suppressed asynchronous cavity-length variations between the two DW laser systems.

Conclusions:

• Cavity-length stabilization via phase locking effectively overcomes the residual cavity-pulling effect.
• The demonstrated technique significantly narrows laser linewidths in DW-AOCs.
• This advancement offers improved frequency stability for next-generation optical clocks.