Observation of novel sub-Doppler trap structures in a magneto optical trap

Last decades of accomplishments in atomic physics are triggered by the invention of laser cooling and trapping technique of magneto optical trap. The studies on this trap revealed that there exist two kinds of forces therein so-called, Doppler and sub-Doppler force. We have found that with different detuning of trap laser between z axis and transverse axes, the normal sub-Doppler trap located at the center fades out while a pair of new sub-Doppler traps appear symmetrically with respect to the center. Varying the experimental conditions such as the trap frequency and the difference of detuning, the depth and the separation of this new structure are measured and compared with theoretical calculation.