Abstract In micro/nano-scaled structures, film has more practical application value for its smooth surface, easy to prepare, more universal, and stable. InSb is a semiconductor material widely used in infrared detection and imaging. In this paper, we demonstrate that the magneto-optical InSb film embedded with Au hemispherical particles in the infrared wavelength of 4–5?μm can behave as a nonreciprocal absorber. Lorentz-Drude model is used to describe the permittivity of InSb in this work. Theoretical analysis shows that the average absorption is greater than 0.5. The physical origin of high nonreciprocal absorption is related to the local surface plasmon resonance (LSPR) of the hemispherical particles. Additionally, the effects of particle radius, incident angle, and direction on nonreciprocal absorption performance are analyzed in detail. The electric field diagram intuitively shows the enhancement mechanism of LSPR to the magneto-optical effect. We believe that our design has a promising application in infrared absorbers, infrared detection, and imaging equipment.
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