We suggest that a three-level cascade medium be used to achieve the switching from normal dispersion to anomalous dispersion.
建议利用三能级级联型介质实现从正常色散到反常色散的变换。
It is shown that for each case, the medium exhibits either normal or anomalous dispersion at the same frequency regime.
结果表明，对于每一种情形，在同一频率区域系统既能呈现正常色散，也能呈现反常色散。
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