Broadband absorption coating for large-curvature surfaces by atomic layer deposition

Area of Science:

• Materials Science
• Optical Engineering
• Nanotechnology

Background:

• Complex 3D structures and large curvature surfaces are crucial for efficient light absorption in applications requiring stray light reduction or energy collection.
• Existing methods often struggle to uniformly coat intricate geometries, limiting their effectiveness.

Purpose of the Study:

• To develop a novel broadband absorption coating strategy for complete coverage of both inner and outer surfaces of quartz tubes.
• To achieve high light absorption across a broad spectrum (400-780 nm) with excellent uniformity on curved surfaces.

Main Methods:

• Utilized atomic layer deposition (ALD) to create a six-layer metal-dielectric film stack.
• Employed a titanium-aluminum-carbon composite as the absorptive metallic layer and aluminum oxide (Al2O3) as the dielectric layer.

Main Results:

• Achieved high absorption (>99%) for the 400-780 nm wavelength band.
• Demonstrated good angle insensitivity (up to 50°) for both P- and S-polarizations on a glass slab.
• Attained an average absorption of 99% on the coated quartz tube with minimal nonuniformity (1.5%) in axial and circumferential directions.

Conclusions:

• The proposed metal-dielectric film stack via ALD offers a robust solution for broadband absorption on complex 3D structures.
• This technology holds significant promise for applications in optical detection, imaging, sensing, and energy management.