A strong control field coupling two empty states of a lambda system makes the medium transparent for a probe pulse. This phenomenon known as electromagnetically induced transparency is here modified by switching a weak microwave field coupling two lower states of the system. As a response to the control and microwave fields, the medium itself acts as a source of an electromagnetic wave which interferes with the incoming pulse. The properties of the net pulse leaving the sample, in particular its magnitude and multipeak shape, will be analyzed in detail, depending on the model parameters.
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