Frequency stabilization of a 739 nm laser to an I2 spectrum for trapped ytterbium ions

We report on the frequency stabilization of a 739 nm Ti:sapphire laser to a hyperfine component of the 127I2 B(1)-X(11) P(70) transition using acousto-optic modulation transfer spectroscopy. A frequency stability of 3.83 × 10-11 around 13 s averaging time is achieved when the laser frequency is stabilized. The observed hyperfine transition of the molecular iodine is an ideal frequency reference for locking the lasers used in experiments with trapped ytterbium ions, since its second-harmonic frequency is the 2S1/2- 2P1/2transition of the ytterbium ion at 369.5 nm. By investigating the line broadening effects due to the iodine vapor pressure and laser power, the locking is optimized to the theoretical signal to noise ratio of this iodine transition.