Wide band optical diode based on passive white light cavities

Abstract

Usually, most optical diodes with high nonreciprocal transmission ratio were accompanied with high insertion loss. The diode made of the asymmetry cavity filled with two-level atoms can simultaneously possess high nonreciprocal transmission ratio and low insertion loss, because the cavity can lower insertion loss and the bistability of the atom can enhance nonreciprocal transmission ratio. However, such diodes can only operate in a very narrow frequency band. In this article we explore two methods to achieve efficient diodes with a wide frequency range. One is using mixed atomic gas instead of a single atom and the other is replacing single-mode cavity with passive white light cavities. By using the two methods, a wide band optical diode with high nonreciprocal transmission ratio and low insertion loss is provided. It will be beneficial for improving the performance of broadband photonic chips and photonic communication.