Enhanced Magneto-Optical Effects in Epsilon-Near-Zero Indium Tin Oxide at Telecommunication Wavelengths

Kenji Ikeda, Tianji Liu, Yasutomo Ota, Nobukiyo Kobayashi, Satoshi Iwamoto

Research output: Contribution to journalArticlepeer-review

Abstract

Epsilon-near-zero (ENZ) materials exhibit near-zero permittivity and induce various intriguing linear and nonlinear optical phenomena. Magneto-optical (MO) effects, which are notoriously weak in the optical domain, have been predicted to be significantly enhanced in ENZ materials, which can facilitate the realization of compact nonreciprocal devices. However, to date, enhanced MO effects have been predominantly observed in effective ENZ media, which are commonly based on complex combinations of photonic nanostructures. It is difficult for these effective media to achieve isotropic ENZ responses, which severely limits their use in the development of ENZ-MO devices. Here, enhanced MO effects in pristine indium tin oxide (ITO) with ENZ properties at technologically important telecommunication wavelengths are demonstrated. MO transmission (reflection) spectroscopy of ITO films with different ENZ wavelengths reveal Faraday (Kerr) rotation peaks around the respective ENZ (EN-one) wavelengths, demonstrating that these observations are due to the intrinsic properties of the ITO materials. The demonstrated mechanism of the MO effect enhancement is universal and can be applied to various ENZ materials, including those incorporating ferromagnetic materials. Native ENZ materials with enhanced MO responses will greatly expand the opportunities for the development of novel nonreciprocal nanophotonic devices, such as on-chip optical isolators and one-way topological waveguides.

Original languageEnglish
Article number2301320
JournalAdvanced Optical Materials
Volume12
Issue number2
DOIs
Publication statusPublished - 2024 Jan 16

Keywords

  • epsilon near zero
  • indium tin oxide
  • magneto-optical effect
  • thin films

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Atomic and Molecular Physics, and Optics

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