Exploration of a vapor cell optical frequency standard scheme implemented using Doppler-free spectroscopy

We implement a compact optical frequency standard scheme with laser frequency locked to the 5 S 1/2 ( F = 2) − 6 P 3/2 ( F ′ = 3) transition of the second excited state of 87 Rb atoms in a 3 mm cubic glass cell, using a Doppler-free saturated absorption spectroscopy. The experimental results show the frequency stability at the level of 2.2 × 10 −12 at 1 s. Furthermore, we conduct an experimental study on the effect of a repump laser on the frequency performance of the saturated absorption spectroscopy optical frequency standard, providing valuable experimental results with reference values for implementing this type of optical atomic clock.