New Laser Uses Light-Matter Beams
A scanning electron microscope image of the polariton laser.
CREDIT: University of Würzburg.
A new kind of laser developed by scientists could potentially replace the conventional semiconductor lasers now widely used in telecommunications and consumer electronics, researchers say.
Normal lasers pump atoms with energy until they emit laser rays. However, the new lasers — which are based on particles that are part matter and light — could require two to 100 times less power than semiconductor lasers to give off laser beams.
The light in each laser beam is made up of just one very specific color or wavelength of light. Unlike normal light, the light in lasers is also coherent, meaning each ray of light within them moves in unison with the others. This allows light energy to become greatly concentrated in laser beams, making them powerful enough to drill or cut through surfaces.
To understand the device, first imagine atoms with an electron orbiting its nucleus. Whenan electron is forced to migrate away from its native atom in a semiconductor material, the empty spot is known as a hole, and can act like a positively charged particle. An exciton is a quasiparticle made up of an electron and its hole. [Read also: US Military to Test Lasers for Warplanes in 2014]
Excitons can merge with light within semiconductors. The result is a quasiparticle known as a polariton. When these break down above a certain threshold of energy, they can give off coherent light. A device that uses polaritons to emit such light is known as a polariton laser.
Scientists had previously devised polariton lasers, but these devices needed conventional lasers to generate polaritons. The new laser — developed by Sven Höfling, a physicist at the University of Würzburg in Germany, and his colleagues — generates polaritons electrically.
"It is a new source of light that can be generated directly with conventional batteries," Höfling said. "By demonstrating electrical pumping, our international research team has moved this sort of laser towards practical applications."
However, to work, the prototype Höfling and his colleagues developed currently needs to get cooled to minus 441 degrees Fahrenheit (minus 263 degrees Celsius) with liquid helium.
"A big goal is to demonstrate this at room temperature," Höfling told TechNewsDaily.
The scientists will detail their findings in the May 16 issue of the journal Nature.