Laser frequency stabilization by modulation transfer spectroscopy and balanced detection of molecular iodine for laser cooling of Yb.

We report laser frequency stabilization by the combination of modulation transfer spectroscopy and balanced detection of a relatively weak hyperfine transition of the R(158)25-0 line of molecular iodine (I), which is used as a new frequency reference for laser trapping and cooling of Yb on the S - P transition. The atomic cloud is characterized by time-of-flight measurements, and an on-resonance optical depth of up to 47 is obtained. We show laser noise reduction and characterize the short-term laser frequency instability by the Allan deviation of the laser fractional frequency. The minimum measured value is 3.9 ×10 at 0.17 s of averaging time.