Research of laser cooling by the optical force between light field and the atoms

The interaction force in the four-waving mixing of a two-level atoms system is analyzed. A new rate equation and the formula of the optical force are obtained. By simulation and analysis with MATLAB software, the impulse curve is obtained. The impulse increases with probe-wave detuning increasing and then tends to saturation. When the Ra-bi frequency takes a certain value, the impulse can obtain relative maximum and the relative maximum increases with the Ra-bi frequency increasing. The relation between the most value and the parameters of Ra-bi frequency and probe-wave detuning is also researched. The impulse occurs minimum when probe-wave detuning is zero and Ra-bi frequency is zero, there is no maximum for the impulse, which is close to 0.02 infinitely, the lowest temperature that can be reached is 248 μk. In addition, T2/T1 also has a significant influence on the impulse. •A new rate equation and the formula of the optical force is obtained.•The relation of impulse with Ra-bi frequency and probe-wave detuning was found.•The maximum and minimum values of the impulse are calculated, and the lowest temperature that can be reached is estimated.•Purely radiation damping has a significant influence on the impulse.