A flexible terahertz absorber can help researchers manage THz radiation on surfaces that are curved or difficult to cover with rigid components. These engineered materials are designed to absorb incident waves across a selected frequency range.
A study in Advanced Optical Materials presents a thin absorber made from patterned aluminium and flexible Kapton. Researchers from IIT Hyderabad, JNCASR and IIT Jodhpur report experimentally measured absorption above 90% from 0.54 to 1.10 THz.
The work explores how a relatively simple structure can combine broadband absorption with mechanical flexibility.
Where a flexible terahertz absorber could be used
- THz sensing and imaging research — developing components that absorb radiation within a defined operating band.
- Electromagnetic wave management — exploring surfaces that reduce unwanted THz reflections.
- Curved photonic components — integrating absorbing films with non-flat surfaces.
- Adaptive THz devices — investigating materials whose absorption response could change under external control.
These are proposed application directions. The paper demonstrates absorber performance and bending behaviour, rather than a complete sensing or communication system.
How the broadband absorber works
The device uses a metal–dielectric–metal structure. Patterned aluminium forms the top layer, a 50-micrometre Kapton film provides the flexible spacer, and a continuous aluminium layer forms the backing.
The patterned surface supports several interacting resonances. Their overlapping responses create a broad absorption band. Meanwhile, the metal backing blocks transmission through the device.
As a result, researchers can estimate absorption from reflected power when transmission is negligible.
How THz-TDS measures absorber performance
The team characterised the flexible terahertz absorber using reflection-mode terahertz time-domain spectroscopy. A dry nitrogen environment reduced interference from atmospheric water vapour.
Measurements under moderate bending remained close to the flat-sample response. At stronger curvature, changes in reflected-beam collection increased measurement uncertainty. This highlights why curved samples need careful measurement geometry.
The researchers also simulated a modified design incorporating vanadium dioxide, or VO₂, for thermal tuning. That tuning capability was investigated numerically.
For more background, read our terahertz technology and THz-TDS guide.
Want the full technical detail?
The paper covers absorber fabrication, broadband measurements, bending tests and simulations of thermal tuning.ions.com
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