Ultraviolet light scattering by a silicon Bethe hole.

Area of Science:

• Optics and Photonics
• Materials Science

Background:

• Bethe's theory describes scattering from small holes in perfect electric conductors (PECs) as magnetic dipole radiation.
• Magnetic dipole radiation from Bethe holes has been observed in the near-infrared, but not yet in the ultraviolet (UV) range.
• Silicon (Si) is emerging as a UV plasmonic material due to its interband transitions, crucial for UV spectroscopy and photochemistry.

Purpose of the Study:

• To extend Bethe's theory to the UV range by investigating silicon Bethe holes.
• To analyze the scattering pattern and polarization of UV light interacting with silicon Bethe holes.
• To confirm theoretical predictions experimentally.

Main Methods:

• Theoretical investigation of silicon Bethe holes using Bethe's theory adapted for the UV range.
• Electromagnetic simulations to model scattering patterns and polarization.
• Experimental scattering polarization measurements at a 69-degree incidence angle.

Main Results:

• Simulations confirm that scattered UV light from silicon Bethe holes resembles in-plane magnetic dipole radiation.
• The dipole direction aligns with the incident magnetic field, with predictable deviations at oblique incidence.
• The magnetic dipole nature is maintained for hole diameters below a quarter-wavelength; multipoles emerge above a half-wavelength.

Conclusions:

• Bethe's theory is applicable to silicon Bethe holes in the UV range, demonstrating magnetic dipole scattering.
• Experimental results validate the theoretical predictions for scattering pattern and polarization.
• These findings are valuable for developing UV plasmonic metasurfaces.