Multiband absorbers for the long-wave infrared regime.

Area of Science:

• Optics and Photonics
• Infrared Spectroscopy
• Materials Science

Background:

• Multiband absorption filters are crucial for various optical applications.
• Achieving simultaneous wavelength and intensity selectivity in filters presents a significant challenge.
• Existing methods often lack the precision required for complex spectral shaping.

Purpose of the Study:

• To develop a long-wave infrared (LWIR) multiband absorption filter.
• To demonstrate simultaneous wavelength and intensity selectivity.
• To introduce and validate the spectral dithering technique for filter design.

Main Methods:

• Development of a "spectral dithering" technique for pixel placement.
• Utilizing rigorous coupled-wave method (RCWM) for theoretical modeling.
• Fabrication of a three-band absorption filter and experimental verification.

Main Results:

• Designed and fabricated an LWIR filter with three distinct absorption bands (6-14 μm).
• Demonstrated precise control over wavelength selectivity via pixel patterning.
• Showcased control over intensity selectivity through pixel distribution.
• Experimental results validated the filter's performance using Fourier-transform infrared spectroscopy.

Conclusions:

• The spectral dithering technique enables the creation of highly selective multiband absorption filters.
• This approach offers a scalable method for designing complex spectral filters in the LWIR regime.
• The developed filter shows promise for advanced infrared sensing and optical system applications.