Phase Controlled Electromagnetically Induced Transparency in a Closed Cyclic Lambda Atomic System

In this work, Electromagnetically Induced Transparency (EIT) has been studied in a microwave driven closed cyclic Lambda atomic system. It is observed that in the absence of microwave field a normal transparency window is obtained, but when a microwave field is also applied between hyperfine levels along with the optical fields an amplification and attenuation in EIT signal is observed depending upon the relative phase between fields driving the atomic system. In fact, a new probe field is generated by microwave and coupling field which interfere constructively or destructively with incident probe field leading to either amplification, attenuation or asymmetricity in probe transmission signal. Also, dependency of phase sensitive amplification on ground state decoherence is also studied. This novel, controllable and amplified EIT signal can be potentially used for the transfer of coherent microwave analog or digital message signal over larger distance using optical fibers where amplification is preliminary requirement.