Deep‐UV Lithography of Nanocomposite Thin Films into Magnetooptical Gratings with Submicron Periodicity

Abstract

AbstractIncompatibility of conventional magneto‐optical (MO) materials with photonic‐system fabrication processes constitutes a major technological roadblock limiting their integration into photonic devices, especially for micro‐ or nano‐patterned films. This paper proposes a photolithography approach toward MO micro‐ and nano‐patterns, based on hybrid photosensitive matrices doped with magnetic nanoparticles to concentrations as high as 20 % vol. The as‐prepared and characterized nanocomposite thin films exhibit excellent MO properties: a high Faraday rotation (3300°/cm), comparable with the best existing materials that nevertheless require much more involved processes. The photosensitive matrices allow patterned gratings with a wide range of periods (100 μm to 500 nm), using a simple procedure at room temperature. The fabricated gratings exhibit well‐defined regular structures and resolutions suitable for optical applications, including those at telecommunications wavelengths. Finally, direct applications of the proposed material and its associated process are demonstrated on two examples: 1) a magneto‐optical grating in free‐space and 2) in combination with a waveguide. The obtained optical and MO results are consistent with simulations.