Unidirectional Amplification with Simple Lambda-Type Three-Level Atomic System

Unidirectional amplification of light plays an indispensable role in optical signal processing and optical communication. It can not only amplify the signal light, but also provide a key protection to avoid the signal being affected by the reverse stray light. In this paper, unidirectional amplification of light is achieved with the simple Lambda-type three-level atomic system. Using only one control field, a gain of more than 25 dB for the forward signal and an isolation of more than 30 dB for the backward one is realized using the rubidium atomic gas. Furthermore, the effects of the rubidium cell temperature and the intensity of the control field on the unidirectional amplification are also investigated in detail.