Influence of laser sources with different spectral properties on the performance of vapor cell atomic clocks based on lin‖lin CPT

We evaluate the influence of 2 types of laser sources with different spectral profiles on the performance of vapor cell atomic clocks based on lin‖lin coherent population trapping (CPT) resonances. We show that a short-term stability of 1 − 2 · 10⁻¹¹τ{−1/2} may be reached in a compact system using a modulated vertical cavity surface-emitting laser. Here the stability is limited by the detection noise level and can be improved up to a factor of 4 by increasing the lock-in detection frequency to several tens of kilohertz, which is not possible in standard double resonance atomic clocks. We compare these results with CPT prepared under the same experimental conditions, using 2 phase-locked extended cavity diode lasers, with which we predict a challenging short-term stability of 1 − 3 · 10⁻¹³τ^−1/2, comparable to the state-of-the-art laser-pumped Rb-clocks.