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All dielectric Absorber for Terahertz Imaging

Value Proposition
For decades, there has been tremendous interest on Terahertz (THz) imaging, due to its promise for safe and nondestructive imaging for some fascinating applications. This range from security screening, detecting illicit drugs to identifying hazardous trace gases. Subsequently, many techniques have been develop based on the terahertz time-domain spectroscopic (THz-TDS) technique. These techniques failed due to acquisition time too long to perform real time imaging. Some required complicated and expensive system designs. While others have low efficiency of the absorber layer in the sub-terahertz ranges.

A team of Duke’s researchers has proposed and demonstrated an alternative approach to this problem. Their device utilizes all-dielectric metasurface absorbers that act as universal converters of radiation. Incident THz waves are absorbed by the metasurface, converted to heat, and subsequently detected by an infrared camera. The metasurface consisting of sub-wavelength cylindrical resonators that achieve diffraction limited imaging at THz frequencies without cooling. The low thermal conductivity and diffusivity significantly limits the thermal conduction between neighboring pixels, thus improving spatial resolution and imaging time. Experimental results showed the absorbance of the all-dielectric metasurface was as high as 96% at a frequency of 603 GHz and achieved a thermal responsivity of 2.16 x 104 K/W at a modulation speed of 1/4 Hz.

Advantages Imaging in the millimeter-wave and terahertz ranges, with:

  • Real-time imaging
  • High responsivity
  • Low cost
  • Simpler design and configuration
  • Scalable over the electromagnetic spectrum
  • Does not require cooling components


  • Xinyu Liu, Kebin Fan, Ilya V. Shadrivov, and Willie J. Padilla, “Experimental realization of a terahertz all-dielectric metasurface absorber,” Opt. Express 25, 191-201 (2017).
  • Kebin Fan, Jonathan Y. Suen, Xinyu Liu, and Willie J. Padilla, “All-dielectric metasurface absorbers for uncooled terahertz imaging,” Optica 4, 601-604 (2017)

Willie Padilla
Professor in the Department of Electrical and Computer Engineering
Duke University

Duke File (IDF) Number



  • Fan, Kebin
  • Liu, Xinyu "Xinyu"
  • Padilla, Willie
  • Suen, Jon

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Pratt School of Engineering