Narrow-band wavelength tunable filter based on asymmetric double layer metallic grating

Area of Science:

• Optics and Photonics
• Materials Science
• Nanotechnology

Background:

• Metallic gratings are crucial for manipulating light.
• Asymmetric structures offer unique optical responses compared to symmetric ones.
• Understanding Fano-like resonance is key to designing optical filters.

Purpose of the Study:

• To theoretically investigate the optical properties of asymmetric double layer metallic gratings.
• To explore the factors contributing to asymmetry and their effect on optical response.
• To demonstrate the potential for developing tunable narrow-band filters.

Main Methods:

• Theoretical analysis of optical properties.
• Numerical computation methods for result validation.
• Analytical modeling based on Fano-like resonance.

Main Results:

• A distinct narrow-band transmission dip was observed at normal incidence in asymmetric structures.
• The number of transmission dips (one or two) is controllable by the down layer grating thickness.
• The wavelength of the transmission dip is tunable via the top layer grating thickness.
• Linear and polynomial relationships were found between structural parameters and optical properties.

Conclusions:

• Asymmetric double layer metallic gratings can produce a single, tunable narrow-band transmission dip.
• The findings support the development of subwavelength metallic-grating-based tunable wavelength filters.
• Precise control over optical response is achievable through structural parameter manipulation.