Optical frequency standard at 1.54 μm based on the HI molecule and Extended Cavity Laser Diode

We have developed and characterized an original optical frequency standard based on the IR absorption line R(3) of the HI molecule. Accurate FM-spectroscopy of hydrogen iodide was performed by an extended cavity laser diode (ECLD). By the FM sideband technique we achieved absolute frequency stabilization of the ECLD to the absorption line central frequency of 194.536 THz. The novelty of this work comes from using a non conventional molecular reference, state-of-the-art ECLDs, and two or more nested control loops for a stiff stabilization of the optical oscillator.