24
PHVSICS OF THE IMPOSSIBLE
attempts to create a true invisibility cloak. The individual atoms inside
a metamaterial would have to be modified to bend a light beam like a
snake.
METAMATERIALS FOR VISIBLE LIGHT
The race is on.
Ever since the announcement that metamaterials have been fabricated in the laboratory there has been a stampede of activity in this
area, with new insights and startling breakthroughs coming every few
months. The goal is clear: to use nanotechnology to create metamaterials that can bend visible light, not just microwaves. Several approaches have been proposed, all of them quite promising.
One proposal is to use off-the-shelf technology, that is, to borrow
known techniques from the semiconductor industry to create new
metamaterials. A technique called "photolithography" lies at the heart
of computer miniaturization and hence drives the computer revolution. This technology enables engineers to place hundreds of millions
of tiny transistors onto a silicon wafer no bigger than your thumb.
The reason that computer power doubles every eighteen months
(which is called Moore's law) is because scientists use ultraviolet radiation to "etch" tinier and tinier components onto a silicon chip. This
technique is very similar to the way in which stencils are used to create colorful T-shirts. (Computer engineers start with a thin wafer and
then apply extremely thin coatings of various materials on top. A plastic mask is then placed over the wafer, which acts as a template. It contains the complex outlines of the wires, transistors, and computer
components that are the basic skeleton of the circuitry. The wafer is
then bathed in ultraviolet radiation, which has a very short wavelength, and that radiation imprints the pattern onto the photosensitive
wafer. By treating the wafer with special gases and acids, the complex
circuitry of the mask is etched onto the wafer where it was exposed to
ultraviolet light. This process creates a wafer containing hundreds of
millions of tiny grooves, which form the outlines of the transistors.) At
PHVSICS OF THE IMPOSSIBLE
attempts to create a true invisibility cloak. The individual atoms inside
a metamaterial would have to be modified to bend a light beam like a
snake.
METAMATERIALS FOR VISIBLE LIGHT
The race is on.
Ever since the announcement that metamaterials have been fabricated in the laboratory there has been a stampede of activity in this
area, with new insights and startling breakthroughs coming every few
months. The goal is clear: to use nanotechnology to create metamaterials that can bend visible light, not just microwaves. Several approaches have been proposed, all of them quite promising.
One proposal is to use off-the-shelf technology, that is, to borrow
known techniques from the semiconductor industry to create new
metamaterials. A technique called "photolithography" lies at the heart
of computer miniaturization and hence drives the computer revolution. This technology enables engineers to place hundreds of millions
of tiny transistors onto a silicon wafer no bigger than your thumb.
The reason that computer power doubles every eighteen months
(which is called Moore's law) is because scientists use ultraviolet radiation to "etch" tinier and tinier components onto a silicon chip. This
technique is very similar to the way in which stencils are used to create colorful T-shirts. (Computer engineers start with a thin wafer and
then apply extremely thin coatings of various materials on top. A plastic mask is then placed over the wafer, which acts as a template. It contains the complex outlines of the wires, transistors, and computer
components that are the basic skeleton of the circuitry. The wafer is
then bathed in ultraviolet radiation, which has a very short wavelength, and that radiation imprints the pattern onto the photosensitive
wafer. By treating the wafer with special gases and acids, the complex
circuitry of the mask is etched onto the wafer where it was exposed to
ultraviolet light. This process creates a wafer containing hundreds of
millions of tiny grooves, which form the outlines of the transistors.) At