Applications of magneto-optical waveguides in integrated optics: review

TLDR

Magneto‑optical garnets offer high Faraday rotation with low loss in the near‑infrared, making them the sole material considered for nonreciprocal devices such as isolators and circulators, yet practical integrated versions remain scarce despite numerous theoretical and experimental concepts. The paper reviews the current state of garnet‑film applications in integrated optics. The review discusses techniques for integrating garnets with semiconductor materials.

Abstract

Magneto-optical garnets combine high Faraday rotation with low optical losses in the near-infrared region where optical communication through glass fiber is established. In this spectral range, garnets are the only materials discussed to realize nonreciprocal devices as optical isolators and circulators. Although such devices are available as micro-optical components, practical versions of their integrated counterparts are still lacking. Numerous concepts have been developed theoretically, many of which are tested experimentally. We present an overview of the state of the art of the applications of garnet films in integrated optics. Also, the technique of combining garnets with semiconductor materials is discussed.