Optical Isolation with Optical Parametric Amplification in an Atomic System

TLDR: In this article , a magnet-free active optical non-reciprocal (AON) device based on optical parametric amplification is demonstrated experimentally in a coherent three-level atomic configuration.

Abstract: Magnet‐free active optical nonreciprocal (AON) devices free from insertion loss help to establish optical information processing networks involving weak signals without introducing external magnetic fields. However, considering the necessary resonant condition for amplification or the presence of optical resonators for most demonstrated magnet‐free AON schemes, it remains a challenge to broaden the AON bandwidth. Here the optical isolation based on optical parametric amplification is demonstrated experimentally in a coherent three‐level atomic configuration. With the phase‐matching condition satisfied or not by oppositely launching the probe beams, they can pass through the medium experiencing parametric amplification or strong resonant absorption. Such magnet‐ and cavity‐free optical isolation exhibits a maximum isolation ratio of 46.5 dB and a broad bandwidth of over 0.85 GHz for the isolation ratio ≥30 dB. The demonstrated results arising from atomic‐coherence‐based optical parametric process with quantum nature pave the way to achieve high‐performance nonreciprocal quantum information processing.