  We analyze a scheme for controlling coherent photon absorption by cavity
electromagnetically induced transparency (EIT) in a three-level atom-cavity
system. Coherent perfect absorption (CPA) can occur when time-reversed symmetry
of lasing process is obtained and destructive interference happens at the
cavity interfaces. Generally, the frequency range of CPA is dependent on the
decay rates of cavity mirrors. When the control laser is settled, the smaller
cavity decay rate causes the wider frequency range of CPA, and the input
intensity is larger to satisfy CPA condition for a given frequency. While the
cavity parameters are determined, Rabi frequency of the control laser has
little effect on the frequency range of CPA. However, with EIT-type quantum
interference, the CPA mode is tunable by the control laser. This means the CPA
with given frequency and intensity of an input laser can be manipulated as the
coherent non-perfect absorption (CNPA). Moreover, with the relative phase of
input probe lasers, the probe fields can be perfectly transmitted and/or
reflected. Therefore, the system can be used as a controllable coherent perfect
absorber or transmitter and/or reflector, and our work may have practical
applications in optical logic devices.
