Optical isolators based on nonreciprocal four-wave mixing

Authors: Muñoz de las Heras, A.; Carusotto, I.

Journal: PHYSICAL REVIEW A

Publication date: 2022/12/29

DOI: 10.1103/PhysRevA.106.063523

Abstract: In this work we propose and theoretically characterize optical isolators consisting of an all-dielectric and nonmagnetic resonator featuring an intensity-dependent refractive index and a strong coherent field propagating in a single direction. Such devices can be straightforwardly realized in state-of-the-art integrated photonics plat-forms. The mechanism underlying optical isolation is based on the breaking of optical reciprocity induced by the asymmetric action of four-wave mixing processes coupling a strong propagating pump field with copropagating signal and idler modes but not with reverse-propagating ones. Taking advantage of a close analogy with fluids of light, our proposed isolation mechanism is physically understood in terms of the Bogoliubov dispersion of collective excitations on top of the strong pump beam. A few most relevant setups realizing our proposal are specifically investigated, such as a coherently illuminated passive ring resonator and unidirectionally lasing ring or Taiji resonators.