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arXiv · 2011.10493

Broad-band plasmonic isolator compatible with low-gyrotropy magneto-optical material

Sevag Abadian·Giovanni Magno·Vy Yam·Béatrice Dagens
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Abstract

Optical isolator remains one of the main missing elements for photonic integrated circuits despite several decades of research. The best solutions up to now are based on transverse magneto-optical effect using either narrow-band resonators or high-gyrotropy magneto-optical materials with difficult integration on usual photonic platforms. We propose in this paper a radically new concept which enables performing broad-band non-reciprocal transmission even in the case of low-gyrotropy material. The principle explores the separation of back and forth light paths, due to the magneto-biplasmonic effect, i.e., the coupled mode asymmetry induced in plasmonic slot waveguides loaded with a magneto-optical (MO) layer. We show numerically that such a metal-MO dielectric-metal slot waveguide combined with suitable side-coupled lossy rectangular nanocavities gives more than 18 dB isolation ratio on several tens of nanometers bandwidth, with only 2 dB insertion losses. We propose an analytical approach describing such a magneto-plasmonic slot waveguide to identify the involved physical mechanisms and the optimization rules of the isolator. Additionally, we show that low-gyrotropy material (down to ~0.005) can be considered for isolation ratio up to 20 dB, opening the road to a new class of integrated isolators using easy-to-integrate hybrid or composite materials.

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Sevag Abadian, Giovanni Magno, Vy Yam, Béatrice Dagens. 2020-11-20. Broad-band plasmonic isolator compatible with low-gyrotropy magneto-optical material. https://doi.org/10.1364/oe.415969

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