Potassium plasmonic material

Low-loss across visible

An ultra-flat potassium film deposited via a rapid slipping-assisted oxide-free crystallization process achieves a measured damping rate of 2.27 meV, breaking the loss-confinement tradeoff of noble metals.

Zhang, Yi · Yang, Yuhan · Liang, Jie · Yao, Pengcheng · Fu, Hanyu · Khurgin, Jacob B. · Hu, Fengrui · Zhu, Jia · Zhu, Shining · Zhou, Lin L.

Light: Science and Applications 2026

Specifications

Optical damping rate

{'zh': '2.27', 'en': '2.27'} meV

Imaginary permittivity

{'zh': '0.1', 'en': '0.1'}

Advantages

Loss reduced to few meV

The measured optical damping rate is only 2.27 meV, about an order of magnitude lower than typical noble metals, enabling longer propagation lengths and stronger field enhancements.

Low loss across visible and NIR

The imaginary permittivity stays around 0.1 across the entire 400–2000 nm range, so device designers are no longer forced to avoid loss peaks at the expense of operating wavelength.

Strong confinement without extra loss

Near-field measurements confirm deeply subwavelength mode confinement while maintaining low loss, bypassing the loss-confinement tradeoff of previous plasmonic systems.

Applications

• Plasmonic devices：Use it for waveguides and antennas to get longer propagation and stronger fields.
• Nanophotonics：Enables low-loss light manipulation at the nanoscale, free from noble-metal loss limits.
• Optical sensing：Low loss yields higher quality factors, boosting sensing signals.
• Plasmonic catalysis：Low-loss films support stronger local fields to drive plasmon-mediated reactions.