Coherent driving of Tm3+:YAG ions using a complex hyperbolic secant optical field

We investigate the coherent driving of atomic systems by Complex Hyperbolic Secant (CHS) pulses in optical domain. First, with the help of a Rapid Adiabatic Passage approach we get physical insight into the process. We discuss the limiting factors on spectral selectivity and transfer efficiency, such as finite coherence lifetime and excitation finite duration. Then, with a highly-stabilized cw laser and fast electronic equipment, we experimentally explore the CHS process at mu s-timescale in a Tm3+:YAG crystal. We demonstrate efficient adiabatic transfer over a few hundreds of kHz-wide spectral interval within the inhomogeneous linewidth. We calculate and detect the Free Induction Decay signal as the signature of the atomic coherences during the process.