Tiny metal resonators can be used to create a material with tunable responses to an applied voltage. Combined with a semiconductor substrate, they can be used to control technologically promising terahertz radiation. Electromagnetic radiation with frequencies lying between the microwave region and the infrared — so-called terahertz radiation — holds great promise for imaging and sensing applications. It is non-ionizing, and therefore causes less damage to biological tissue than conventional, higher-energy X-rays. It penetrates plastics and clothing, but not metal, and so is ideal for security screening and non-contact testing or inspection.
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