Prototyping of Novel Isolator Design Based on Cavity Magnonics

The cooperation of coherent and dissipative coupling produces nonreciprocity in cavity magnonic devices, in which the isolation ratio can theoretically be infinite at a matching condition (zero-damping condition). In this article, we report the design of such a prototype, where a yttrium–iron–garnet sphere is strongly coupled to a planar microwave cavity resonator. Three different microwave isolator design schemes have been constructed according to the latest developed theory, resulting in considerable isolation, design flexibility, and device size reduction. Fabricated devices achieved the isolation of 65.8, 40.5, and 31.0 dB and the corresponding insertion loss of 23.6, 0.7, and 0.7 dB, respectively. These devices promise to be useful in microwave range applications that demand miniature, low cost, and narrowband. Furthermore, our magnonic device may open a promising way for signal processing through the manipulation of coherent and dissipative coupling.