1a. With an additional control laser of very high intensity applied transverse to the cavity axis, the single-atom EIT condition is achieved and maximum transmission is recovered See Fig.

By varying the groove spacing, the diameter of the single or double diameter hole, and the rear air cavity depth and content, one can obtain absorption over a wide variety of frequencies.

The proposed scheme only requires three single-mode cavity fields and one classical field, thus it is easier to be realized in experiment by using cavity QED technique.