Abstract
We demonstrate the realization of a new hybrid magnetoplasmonic thin film structure that resembles the classical optical analog of electromagnetically induced absorption. In transmission geometry our gold nanostructure embedded in an EuS film induces giant Faraday rotation of over 14° for a thickness of less than 200 nm and a magnetic field of 5 T at T=20 K. By varying the magnetic field from −5 to +5 T, a rotation tuning range of over 25° is realized. As we are only a factor of 3 away from the Faraday isolation requirement, our concept could lead to highly integrated, nonreciprocal photonic devices for light modulation, optical isolation, and optical magnetic field sensing. DOI:https://doi.org/10.1103/PhysRevX.7.021048 Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI. Published by the American Physical Society
Highlights
The combination of plasmonic nanostructures with magneto-optic (MO) materials enables nanoscale systems that offer magnetic tunability as well as strong nonreciprocal optical response in ultracompact structures [1,2,3,4,5,6]
We exploit the design flexibility enabled by the use of EuS as magneto-optic material to realize a hybrid magnetoplasmonic thin film structure that represents the classical optical analog of electromagnetically induced absorption (EIA)
Unlike in previous approaches where the low quality factor of localized surface plasmon resonances limited the Faraday rotation enhancement, the coupling regime of EIA allows us to leverage both the highquality factor of the waveguide resonances and the large oscillator strength of the plasmons. Both these aspects result in dramatically increased light-matter interaction and MO response
Summary
The combination of plasmonic nanostructures with magneto-optic (MO) materials enables nanoscale systems that offer magnetic tunability as well as strong nonreciprocal optical response in ultracompact structures [1,2,3,4,5,6]. The direction of the polarization rotation is determined by the direction of the applied magnetic field and not by the direction of the wave vector of the incident light This fact fundamentally distinguishes it from effects such as optical activity [18]. Considerable attention was received by a recent approach where the MO response of a dielectric thin film is enhanced by the attachment of a plasmonic grating [13,14]. This technique allows the amplified MO response to be spectrally tailored by tuning the grating parameters [47]. The MO performance of such a system is limited by the low Q factor of the plasmon resonances of the grating
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