Low insertion loss optical isolator with widely tunable frequency

Abstract

An optical isolator with a low insertion loss and high isolation is desirable for quantum networks and modern optical communication. Here, we realize an optical isolator with the far-off resonant Raman process in a thermal Λ-type atomic system. The experimental results show a high isolation, ultra-low insertion loss, and widely tunable frequency simultaneously. The maximum isolation is more than 30 dB with 0.07 dB insertion loss. And, the frequency of the isolation can be tuned continuously over 1.2 GHz. This high-performance magnetic-free optical isolator offers opportunities for applications in integrated optics and quantum networks.