Mitigation of Temperature-Induced Light-Shift Effects in Miniaturized Atomic Clocks

Area of Science:

• Atomic, Molecular, and Optical Physics
• Precision Measurement
• Quantum Technologies

Background:

• Miniature atomic clocks (MACs) based on coherent population trapping (CPT) are crucial for portable timing applications.
• Temperature-induced light-shift effects degrade the frequency stability of CPT-based MACs.
• Existing stabilization techniques require further enhancement for improved mid- and long-term performance.

Purpose of the Study:

• To investigate the impact of additional stabilization loops on the frequency stability of a CPT-based MAC.
• To quantify the individual and combined benefits of novel servo loops for reducing temperature-induced effects.
• To demonstrate enhanced frequency stability in a miniaturized CPT atomic clock.

Main Methods:

• Implemented a servo loop to stabilize the vertical-cavity surface-emitting laser (VCSEL) chip temperature using atomic vapor output.
• Developed a second servo loop to maintain optimal microwave power for maximum optical absorption, reducing laser power dependence.
• Conducted experimental tests on a miniaturized CPT-clock physics package using a chip-VCSEL tuned to the Cs D1 line (895 nm).

Main Results:

• The VCSEL temperature compensation technique improved clock Allan deviation by a factor of 4 at 10^4 s.
• Simultaneous operation of both servo loops enhanced clock fractional frequency stability by a factor of 7 at 10^4 s.
• The clock achieved a fractional frequency stability of 7.5x10^-11 at 1 s and better than 2x10^-11 at 1 day.

Conclusions:

• The implemented stabilization loops effectively mitigate temperature-induced light-shift effects in CPT-based MACs.
• Combined servo loop operation yields significant improvements in mid- and long-term frequency stability.
• The demonstrated performance advances the capabilities of miniaturized atomic clocks for demanding applications.