Laser-pumped paraffin-coated cell rubidium frequency standard

We have realized and studied a rubidium atomic frequency standard based on a paraffin-coated cell, exhibiting a short-term frequency stability <3 × 10⁻¹² <i>τ</i>^−1/2 between <i>τ</i> = 1 and 100 s. Characterization of the wall-coating is performed by measuring the <i>T</i>₁and <i>T</i>₂ relaxation times. Perturbations of the medium- to long-term clock stability, due to variations in the laser-intensity, laser frequency, the microwave power shift, and the shifts due to temperature variations are measured and analyzed. A method for reducing the intensity light-shift by detuning the laser frequency and the resulting improvement in clock stability is demonstrated. This work is of relevance for further improvements on Rb cell standards using anti-relaxation wall-coating technology.