Sub-Doppler spectroscopy of molecular iodine around 541 nm with a novel solid state laser source

We report high resolution sub-Doppler spectroscopy of molecular iodine hype rfine transitions around 541 nm. A novel solid state source, based on a dio de laser, a Yb+ fiber amplifier and a periodically-poled KTiOPO4 crystal, w as developed, having a continuous tunability range of 1.2 THz. The performa nce of this crystal for doubling 1083 nm laser radiation is demonstrated fo r the first time, as well as the use of a broad band Yb-doped fiber amplifi er for Doppler-free spectroscopy. Preliminary results for the frequency sta bility of the 1083 nm diode laser locked to an iodine hyperfine line are re ported. This source can be used as a compact frequency standard for precisi on measurements of the atomic helium and determination of the fine structur e constant alpha. (C) 2000 Elsevier Science B.V. All rights reserved.