Light shift manipulation and suppression in a double pass optical-magnetic double resonance system

A double pass optical-magnetic double resonance system is proposed and applied for observing and manipulating the light shift in metastable ⁴He. By adjusting the degree of overlap in space between the incident and retro-reflected laser beams, the manipulation on light shift is realized and a flat range for light shift insensitive to optical frequency detuning can be formed. A simple hole-burning model based on velocity-selective optical pumping, including the velocity diffusion effect caused by velocity-changing collisions, is adopted to qualitatively clarify the light shift observed in the double pass system. (paper)