Optical circulator

Fiber-optic circulators are used to separate optical signals that travel in opposite directions in an optical fiber, for example to achieve bi-directional transmission over a single fiber.

[1] Because of their high isolation of the input and reflected optical powers and their low insertion loss, optical circulators are widely used in advanced fiber-optic communications and fiber-optic sensor applications.

This can only happen when the symmetry of the system is broken, for example by an external magnetic field.

In 1965, Ribbens reported an early form of optical circulator that utilized a Nicol prism with a Faraday rotator.

[6][7][8][9] In 2016, Scheucher et al. have demonstrated a fiber-integrated optical circulator whose nonreciprocal behavior originated from the chiral interaction between a single 85Rb atom and the confined light in a whispering-gallery mode microresonator.