In 1965, Caltech alumnus Gordon Moore (Ph.D. '54), a life member of the Caltech Board of Trustees, predicted that integrated circuits would get twice as complicated and half as expensive every two years. However, because of the fundamental limits on power dissipation and transistor density allowed by current silicon semiconductors, the scaling predicted by Moore's Law should soon end.
A newly created nano-architected material exhibits a property that previously was just theoretically possible: it can refract light backward, regardless of the angle at which the light strikes the material. This property is known as negative refraction and it means that the refractive index—the speed that light can travel through a given material—is negative across a portion of the electromagnetic spectrum at all angles. Refraction is a common property in materials; think of the way a straw in a glass of water appears shifted to the side, or the way lenses in eyeglasses focus light. But negative refraction does not just involve shifting light a few degrees to one side. Rather, the light is sent in an angle completely opposite from the one at which it entered the material.
This has not been observed in nature but, beginning in the 1960s, was theorized to occur in so-called artificially periodic materials—that is, materials constructed to have a specific structural pattern. Only now have fabrication processes have caught up to theory to make negative refraction a reality.
The new material achieves its unusual property through a combination of organization at the nano- and microscale and the addition of a coating of a thin metal germanium film through a time- and labor-intensive process. Under an electron microscope, the new material's structure resembles a lattice of hollow cubes. Each cube is so tiny that the width of the beams making up the cube's structure is 100 times smaller than the width of a human hair. The lattice was constructed using a polymer material, which is relatively easy to work with in 3D printing, and then coated with the metal germanium.
The technology has potential applications for telecommunications, medical imaging, radar camouflaging, and computing. The current work is a step towards demonstrating optical properties that would be required to enable 3D photonic circuits. Because light moves much more quickly than electrons, 3D photonic circuits, in theory, would be much faster than traditional ones.
The Nano Letters paper is titled "Dispersion Mapping in 3-Dimensional Core–Shell Photonic Crystal Lattices Capable of Negative Refraction in the Mid-Infrared."
A newly created nano-architected material exhibits a property that previously was just theoretically possible: it can refract light backward, regardless of the angle at which the light strikes the material. This property is known as negative refraction and it means that the refractive index—the speed that light can travel through a given material—is negative across a portion of the electromagnetic spectrum at all angles. Refraction is a common property in materials; think of the way a straw in a glass of water appears shifted to the side, or the way lenses in eyeglasses focus light. But negative refraction does not just involve shifting light a few degrees to one side. Rather, the light is sent in an angle completely opposite from the one at which it entered the material.
This has not been observed in nature but, beginning in the 1960s, was theorized to occur in so-called artificially periodic materials—that is, materials constructed to have a specific structural pattern. Only now have fabrication processes have caught up to theory to make negative refraction a reality.
The new material achieves its unusual property through a combination of organization at the nano- and microscale and the addition of a coating of a thin metal germanium film through a time- and labor-intensive process. Under an electron microscope, the new material's structure resembles a lattice of hollow cubes. Each cube is so tiny that the width of the beams making up the cube's structure is 100 times smaller than the width of a human hair. The lattice was constructed using a polymer material, which is relatively easy to work with in 3D printing, and then coated with the metal germanium.
The technology has potential applications for telecommunications, medical imaging, radar camouflaging, and computing. The current work is a step towards demonstrating optical properties that would be required to enable 3D photonic circuits. Because light moves much more quickly than electrons, 3D photonic circuits, in theory, would be much faster than traditional ones.
The Nano Letters paper is titled "Dispersion Mapping in 3-Dimensional Core–Shell Photonic Crystal Lattices Capable of Negative Refraction in the Mid-Infrared."
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