Absolute frequency stabilization of an extended-cavity diode laser against Doppler-free H_2^17O absorption lines at 1384 μm

We report the frequency stabilization of a cw extended-cavity diode laser against saturated absorption lines of the H(2)O17 isotopologue of water vapor at around 1.384 microm. The saturation of rotovibrational transitions is achieved by filling a high-finesse optical resonator with H(2)O17 at low pressure and by locking the laser frequency to the resonator by using the Pound-Drever-Hall technique. Absolute frequency stabilization is obtained, locking the cavity resonance to the center of the sub-Doppler line by means of the wavelength modulation method. A relative frequency stability of sigma(y)(tau)=10(-13)(0.1tau(-2)+0.9)(1/2) is demonstrated for integration times in the range 4 ms<tau<30 s.