Nonlinearity-based circulator.

Commercially available nonreciprocal devices, such as isolators and circulators, play a fundamental role in communication systems. Since they commonly rely on magnetic materials, they tend to become bulky, expensive, and difficult to be integrated in conventional microelectronic circuits. Here, we explore the functionality of a magnetic-free circulator where reciprocity is broken by suitable geometric asymmetries combined with tailored nonlinearities. We show that it is possible to operate a fully passive coupled resonator system without external bias like a circulator for pulsed signals impinging at its ports within a desired range of intensities. The functionality can be applied to a variety of physical systems, ranging from electronics to photonics and acoustics. [ABSTRACT FROM AUTHOR]