Magnetless circulators for electromagnetic and acoustic waves

Concepts and techniques that emerged in microwave engineering may have significant impact in other closely-related scientific fields, such as optics or even acoustics. In particular, non-reciprocal microwave components such as isolators and circulators have recently been achieved for acoustic waves, significantly enhancing our ability to control sound with a novel class of nonreciprocal acoustic devices. Interestingly, these recent developments have made their way back to the field of microwaves, inspiring new designs for RF circulators without magnets. We discuss here recent design iterations of magnetless circulators and isolators for electromagnetic and acoustic waves, highlighting a fruitful research strategy at the frontier of two scientific fields.