Implementing infrared metamaterial perfect absorbers using dispersive dielectric spacers

Area of Science:

• Optics and Photonics
• Materials Science
• Nanotechnology

Background:

• Metamaterial perfect absorbers (MPAs) typically use non-dispersive dielectric spacers.
• Dispersive materials offer potential for advanced optical device functionalities.
• Integrating functional materials with MPAs is crucial for microelectromechanical systems (MEMS).

Purpose of the Study:

• To design, fabricate, and characterize MPAs utilizing a highly dispersive dielectric spacer.
• To investigate the impact of material dispersion on MPA absorption characteristics.
• To demonstrate the compatibility of dispersive spacers with functional MEMS devices.

Main Methods:

• Rigorous coupled wave analysis (RCWA) was employed for modeling MPA absorption.
• The dispersive permittivity of silicon nitride thin films was experimentally measured.
• MPA structures were fabricated and characterized using spectroscopy.

Main Results:

• Two distinct perfect absorption peaks were observed in the 8 μm to 20 μm wavelength range.
• Experimental results aligned with theoretical calculations and numerical simulations.
• The dispersive nature of silicon nitride facilitated shared resonant modes and reduced sensitivity to structural variations.

Conclusions:

• MPAs incorporating dispersive dielectric materials, like silicon nitride, enable enhanced optical performance.
• The use of dispersive spacers broadens the applicability of MPAs in functional devices.
• This approach supports the development of advanced, stable optical components for MEMS.