Microcell atomic clock using laser current-actuated power modulation with 10^-12 range stability at 1 day.

Area of Science:

• Physics
• Atomic Physics
• Metrology

Background:

• Atomic clocks are crucial for timekeeping and navigation.
• Microcell atomic clocks offer miniaturization potential.
• Coherent-population trapping (CPT) and Ramsey spectroscopy are key techniques.

Purpose of the Study:

• To present a novel coherent-population trapping (CPT) microcell atomic clock.
• To utilize symmetric auto-balanced Ramsey (SABR) spectroscopy for improved clock performance.
• To demonstrate the feasibility of integrated, high-stability chip-scale atomic clocks.

Main Methods:

• Implementation of a pulsed SABR sequence via direct current-based power modulation of a vertical-cavity surface-emitting laser.
• Control of the SABR sequence using a single FPGA-based digital electronics board.
• Real-time tracking of the atomic signal detection window for precise clock operation.

Main Results:

• Achieved clock frequency sensitivity coefficients lower than traditional Ramsey-CPT spectroscopy.
• Measured clock frequency dependence on laser power, microwave power, laser frequency, and detection window timing.
• Demonstrated an Allan deviation of 8 × 10^-10 at 1 s, averaging to the 10^-12 range at 1 day.

Conclusions:

• The SABR-CPT microcell atomic clock exhibits reduced light-shift sensitivity and enhanced long-term stability.
• The developed technology supports the advancement of chip-scale atomic clocks.
• This work paves the way for next-generation miniaturized and high-performance timing devices.