Generating Bessel beams by use of localized modes

Area of Science:

• Optics and Photonics
• Nanotechnology
• Applied Physics

Background:

• Bessel beams offer unique properties like self-reconstruction and non-diffraction.
• Generating sub-wavelength Bessel beams, especially evanescent ones, is challenging.
• Existing methods often lack efficiency or precise control over beam characteristics.

Purpose of the Study:

• To propose and numerically demonstrate a novel method for generating both propagating and evanescent Bessel beams.
• To achieve Bessel beams with sub-wavelength central spot sizes.
• To explore potential applications in areas like high-density optical recording.

Main Methods:

• Propagating Bessel beams: Utilized a pair of distributed Bragg reflectors with a resonant point source for selective transmission.
• Evanescent Bessel beams: Employed transmission of a resonant point source through a thin film, leveraging multiple scattering.
• Numerical simulations were performed to validate the generation and characteristics of both beam types.

Main Results:

• Propagating Bessel beams with a ~0.5λ0 spot size maintained over >3000λ0.
• Evanescent Bessel beams with a ~0.34λ0 spot size achieved over 0.14λ0 using a glass thin film.
• Demonstrated the ability to further reduce the spot size of evanescent Bessel beams by adjusting material parameters.

Conclusions:

• The proposed methods offer efficient generation of both propagating and evanescent Bessel beams.
• Achieved sub-wavelength spot sizes, particularly for evanescent Bessel beams, opening possibilities for advanced optical applications.
• The technique shows promise for high-density data storage and sub-wavelength imaging.