[Intercross cascaded dual-layer resonant sub-wavelength gratings]

Area of Science:

• Optics and Photonics
• Materials Science

Context:

• Sub-wavelength gratings are crucial for optical applications.
• Existing resonant sub-wavelength gratings have limitations in spectral width and optical variable effects.
• Developing advanced grating structures is essential for improved security features.

Purpose:

• To introduce and analyze an intercross cascaded dual-layer resonant sub-wavelength grating structure.
• To broaden the resonant wavelength width and enhance optical variable effects.
• To investigate the mechanism behind the full-width-at-half-maximum (FWHM) broadening.

Summary:

• A novel security grating structure, the intercross cascaded dual-layer resonant sub-wavelength grating, is presented.
• This structure broadens the resonant wavelength width and improves optical variable effects.
• The FWHM broadening is dependent on energy coupled into the grating waveguide layer, and the structure shows robustness against incident angle variations and fabrication errors.

Impact:

• The optimized grating structure achieves a maximum FWHM approximately seven times greater than basic resonant gratings.
• The design demonstrates insensitivity to incident angle changes and manufacturing errors.
• This resonant dual grating waveguide structure holds significant potential for industrial applications in security and anticounterfeiting.