Simple and Effective Modulation of Diode Lasers

Diode lasers have recently found wide application in various fields of modern physics, such as spectroscopy, metrology, and atomic physics. Because of their small size, low cost, and high spectral characteristics, the use of such lasers has substantially simplified the conduct of experiments on atomic optics and laser cooling of atoms. When working with alkali metals featuring a hyperfine splitting of their ground state, of principal importance is the use of a two-frequency laser radiation. In that case, radiation at one of the frequencies exerts a force action on the atom in hand by exciting it from one of the hyperfine-structure sublevels of the lower state, while radiation at the other frequency provides for a cyclic character of the interaction between the atom and the laser field. The frequencies of both lasers here must be sufficiently stable in time in order that radiation should be in resonance with the appropriate transitions and the frequency difference be equal to the hyperfine splitting of the ground state of the atom