Washington: Yale University scientists have developed the world`s first anti-laser, in which incoming beams of light interfere with one another in such a way as to perfectly cancel each other out.
The discovery could pave the way for a number of novel technologies with applications in everything from optical computing to radiology.
Conventional lasers, which were first invented in 1960, use a so-called "gain medium," usually a semiconductor like gallium arsenide, to produce a focused beam of coherent light—light waves with the same frequency and amplitude that are in step with one another.
Yale physicist A. Douglas Stone, his colleague Hui Cao and their team call the new device a coherent perfect absorber (CPA).
The team focused two laser beams with a specific frequency into a cavity containing a silicon wafer that acted as a "loss medium."
The wafer aligned the light waves in such a way that they became perfectly trapped, bouncing back and forth indefinitely until they were eventually absorbed and transformed into heat.
Stone believes that CPAs could one day be used as optical switches, detectors and other components in the next generation of computers, called optical computers, which will be powered by light in addition to electrons.
Another application might be in radiology, where Stone said the principle of the CPA could be employed to target electromagnetic radiation to a small region within normally opaque human tissue, either for therapeutic or imaging purposes.
Theoretically, the CPA should be able to absorb 99.999 percent of the incoming light. Due to experimental limitations, the team`s current CPA absorbs 99.4 percent.
The results were published in the Feb. 18 issue of the journal Science.
First Published: Saturday, February 19, 2011, 00:27