研究了梯形四能级冷原子系统的非线性光学行为, 在一微波场耦合两上简并能级时双暗态共振将会出现。在合适的参数条件下, 系统将表现出正常色散与反常色散之间的转变。改变耦合场和微波场的大小能够调控慢光和超光速间的转变。

We study nonlinear optical behaviors of a ladder-type four-level cold atomics, where a radio-frequency field couples upper two-folded levels and double dark resonances can arise. Using appropriately chosen parameters, the system will show the transition between the normal chromatic dispersion and the abnormal chromatic dispersion. Changing the intensities of the coupling field and radio-frequency field can manipulate the shift between the subluminal and the superluminal.