Local modulation of electromagnetic induction transparent spectrum by microwave field

When the ground state of the coupling transition in a Λ-type atom is coupled to two hyperfine levels of a lower state by two weak coherent fields, two sharp and high-contrast absorption lines induced by the microwave fields split the single electromagnetically induced transparent spectrum into three parts. The triple electromagnetically induced transparent spectrum can be locally modulated by adjusting the strength of microwave field and its detuning. This will be useful in multi-channel optical communication and controllable manipulation of atomic system.