It has fascinated physicists and spawned whole new industries, including fiber optics, medical imaging and lasers. All of these technologies have relied on light obeying the laws of optics and behaving in a highly predictable way.

But, as the articles in the current special issue of Physics World on "extreme optics" make clear, physicists are finding ways of breaking and bending the rules -- with profound implications for the future of technology.

Slowing light to a standstill

Light travels at 299,792,458 meters per second in a vacuum. Not surprisingly, it slows down when it meets anything -- be it a piece of glass or a gas of sodium atoms.

But if the sodium atoms have been placed in a particular quantum state by a special laser, it is possible to slow a second laser to the speed of just a few meters per second -- and even stop it in its tracks. As Lene Hau explains, the ability to halt light could lead to new techniques for storing data with light. (p. 35) Contact: Lene Hau, Department of Physics, Harvard University.

Beating the diffraction limit

The "resolution" of optical instruments -- a measure of how close two objects can be while still being able to be told apart -- was once thought to be limited by the wavelength of the light used.

But physicists are now developing ingenious techniques to break that limit in the quest to view ever-smaller objects with optical microscopes. As Vahid Sandoghdar explains, single molecules have been used as light sources to examine objects as small as one hundred millionth of a meter in size. (p. 29) Contact: Vahid Sandoghdar, University of Konstanz, Germany.

Novel optical materials

Send a beam of light into a block of glass, as Isaac Newton first did, and it always bends in a certain direction. But physicists have in recent years been able to build materials that bend the light in the opposite direction.

The new materials emerging from this research could lead to applications in communications, electronics and medical imaging -- and even the possibility of a "perfect lens," as John Pendry explains. (p. 47) Contact: John Pendry, Blackett Laboratory, Imperial College, London.

Ultrafast lasers

The invention of the laser in 1960 revolutionized optics and the impact is still being felt today. Modern laser research now progresses on many fronts: some physicists want brighter lasers, while others -- such as Ferenc Krausz -- want lasers with ever-shorter pulses. Their goal is to create pulses of X-rays that last just for one billion billionth of a second, which would let them study and control the motion of electrons inside atoms. (p. 16) Contact: Ferenc Krausz, Photonics Institute, Vienna University of Technology, Austria.

(Reference: Physics World Digest September 2001 edition)

29-Aug-2001