The researchers will unveil the new lens tomorrow at the Conference on Lasers and Electro-Optics/Quantum Electronics and Laser Science Conference in San Jose, California.Įvan Reed, a physicist at Stanford University in Palo Alto, California, is impressed with the work. They can even force the metamaterial to do things impossible with natural materials, such as switching between a positive and a negative refractive index to flip the direction in which a light beam bends when passing through the material. By heating or cooling the material, researchers can make the resonators rotate in ways that change how the lens bends light. The split-ring resonator "atoms," however, can be placed in exactly the right pattern to lens terahertz light. At some angles the resonator will amplify the light's magnetic field, and at other angles it will amplify the electric field-the same way an atom in the material of a conventional lens interacts with light passing through the lens. Rotating a split-ring resonator through a light beam will change how it interacts with that light. Each gold ring had a small cut to make it a tiny circuit called a split-ring resonator. They laid out tiny gold rings, just 100 microns across, in a grid on a thin wafer of silicon nitride. Physicists from Boston University decided to test the theory by making their own metamaterial lens. Also in theory, they can be specifically designed to work with terahertz frequencies. In theory, they can be designed to alter their own structures in ways that change how they aim and focus light. Metamaterial lenses might solve both problems. And for some frequencies of light-such as terahertz radiation, a type of radiation that falls between the infrared and microwave bands of the electromagnetic spectrum and passes through many materials that block visual and infrared light-ordinary materials developed so far don't work as lenses at all. That's a downside because multiple lenses and complex controls are often needed to guide and focus light with precision.
But such lenses have fixed directions and focal points. Regular lenses focus and aim visible, infrared, and microwave light, making them useful in a variety of everyday devices such as cameras, cell phones, and eyeglasses. The new lens is a metamaterial, an artificial material with a structure made from many tiny parts, and it could drastically expand what lenses can do. X-ray-like imaging without the harmful radiation and cell phones with more bandwidth are closer to reality now that researchers have developed a novel type of lens that works with terahertz frequencies.
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