Cs microcell optical reference with frequency stability in the low 10 range at 1 s.

We describe a high-performance optical frequency reference based on dual-frequency sub-Doppler spectroscopy (DFSDS) using a Cs vapor microfabricated cell and an external-cavity diode laser at 895 nm. Measured against a reference optical signal extracted from a cavity-stabilized laser, the microcell-stabilized laser demonstrates an instability of 3 × 10 at 1 s, in agreement with a phase noise of +40 dBrad/Hz at 1-Hz offset frequency, and below 5 × 10 at 10 s. The laser short-term stability limit is in good agreement with the intermodulation effect from the laser frequency noise.