Overview
A new research effort presents the initial demonstration of a laser-atomic oscillator (LAO) utilizing cesium (Cs) atoms. This system operates analogously to an active mode-locked laser, incorporating a self-excited modulator composed of atoms tuned to a ground-state hyperfine transition frequency. The LAO concept allows configuration as an active atomic clock or a self-oscillating, earth-field atomic magnetometer, generating oscillation signals through both optical and electrical means.
Research Context
Laser-atomic oscillators represent a class of devices designed to leverage atomic transitions to generate stable oscillatory signals. The foundational analogy for an LAO is an active mode-locked laser, wherein the atomic ensemble acts as the self-excited modulating element. Such a design suggests potential for developing compact atomic clocks and high-sensitivity magnetometers. Atomic clocks rely on precise atomic transitions for timekeeping, while atomic magnetometers detect magnetic fields through their influence on atomic energy levels.
Approach
The reported experimental setup involved a Cs-LAO. The device was evaluated in two distinct configurations to assess its performance as an atomic clock and as a magnetometer. When configured as an atomic clock, the system utilized the 0-0 hyperfine transition of cesium atoms. For its operation as a self-oscillating magnetometer, the setup employed a magnetically-sensitive hyperfine transition. The cavity lengths utilized in the presented Cs-LAO ranged from approximately 6.5 cm to 11.4 cm.
Findings
The experimental demonstration yielded specific performance metrics for the Cs-LAO:
- Atomic Clock Configuration: When configured to operate as an atomic clock using the 0-0 hyperfine transition, the Cs-LAO exhibited a short-term fractional frequency instability on the order of $10^{-10}$.
- Magnetometer Configuration: In its configuration as a self-oscillating magnetometer, utilizing a magnetically-sensitive hyperfine transition, the device demonstrated a magnetic field sensitivity of approximately 100 fT/$\sqrt{\rm{Hz}}$ at 60 Hz.
- Device Dimensions: The current experimental Cs-LAO setup incorporated cavity lengths spanning from approximately 6.5 cm to 11.4 cm. Based on this work, the minimal potential length for a Cs-LAO device is indicated to be $\leq1.63$ cm.
Why This Matters
The demonstration of this Cs-LAO, particularly its potential for significant miniaturization to $\leq1.63$ cm, suggests a pathway toward the development of chip-scale atomic clocks and magnetometers. Such compact devices could enable new applications or enhance existing ones where size and power constraints are critical considerations.