The depth of the optical trapping potential in an optical dipole trap (ODT) is proportional to the intensity of the trapping laser light. Decreasing the power in the trapping laser beam therefore decreases the depth of the trapping potential. In the case of RF-driven evaporation, the actual height of the potential barrier confining the atoms is fixed during the evaporation sequence, but the RF knife effectively decreases the depth of this barrier, as previously discussed. For an optical trap, however, evaporation is facilitated by decreasing the laser power and thus lowering the depth of the trapping potential. As a result, the warmest atoms in the trap will have sufficient kinetic energy to be able to make it over the barrier walls and escape the trap, reducing the average energy of the remaining atoms as previously described. While trap depths for ODTs can be shallow (on the order of mK, in terms of temperature), the simplicity of this optical evaporation procedure has helped to make it increasingly popular for BEC experiments since its first demonstrations shortly after magnetic BEC production.